Journal of Facade Design and Engineering 1 (2013) 53–71
DOI 10.3233/FDE-130005
IOS Press

53

Comparison and development of
sustainable office façade renovation
solutions in the Netherlands

Michiel Ritzena,b,∗, Bertold vd Meijdena, Ronald Roversb, Zeger Vroonb,c and Chris Geurtsa,c
aEindhoven University of Technology, The Netherlands
bRiBuilT/Zuyd University of Applied Sciences, The Netherlands
cTNO, The Netherlands

Received: 13 August 2013
Accepted: 14 November 2013

Abstract. Environmental, commercial and societal developments in the Netherlands stimulate the environmental improve-
ment of the existing office building stock. In the Netherlands, about 15% of all office area was vacant in 2012, and the
majority of offices have a relative poor energy performance. To measure the improvement, different assessment tools are
applied. These tools either focus on one aspect, such as operational energy, and result in a specific outcome such as MJ/m2,
or these tools combine different aspects, such as energy and materials, through a weighted system and result in a generic
outcome, such as ‘excellent’. In this research, the relation between assessment outcome and actual environmental impact
is investigated of both types of tools, by reflecting the outcome of the tool to the carrying capacity of a system. The relation
is investigated through a comparison of the energy and material aspect of three office façade renovation solutions using
four different assessment tools. Using a tool in which energy and material impact is related to the carrying capacity, current
energy focused optimization might lead to a sub optimization of actual environmental impact. To illustrate this, a calculated
façade solution is presented with minimal environmental impact based on carrying capacity.

Keywords: Façades, building materials, office buildings, environmental impact

1. Introduction

Between 1990 and 2005 global final energy consumption increased by 23% and CO2 emissions
increased with 25% ((IEA), 2008). This consumption is expected to grow with another 45% between
2002 and 2025 (Ko & Widder, 2011). 20% to 40% of this global energy consumption is consumed in
the built environment (Pérez-Lombard, Ortiz, & Pout, 2008), for more than 86% based on fossil fuels
((USEIA), 2011). Between 1995 and 2005, extraction of fossil fuels increased with 24% (Bruckner,
Giljum, Lutz, & Wiebe, 2012). To lower overall energy consumption in the built environment and
to lower dependency on fossil fuels, it is agreed within the EU that by the end of 2020 all new
buildings are nearly zero-energy buildings, and that by the end of 2018 all new buildings occupied
and owned by public authorities are nearly zero-energy buildings (NZEBs) (EU, 2010). NZEB means
that the building has a very high energy performance and that the low amount of energy required
should be generated to a very significant extent from renewable sources, on-site or nearby, having a

∗Corresponding author: Ir. Michiel Ritzen, Eindhoven University of Technology/Zuyd University of Applied Sciences, The
Netherlands. E-mail: m.j.ritzen@tue.nl.

ISSN 2213-302X/13/$27.50 © 2013 – IOS Press and the authors. All rights reserved
This article is published online with Open Access and distributed under the terms of the Creative Commons Attribution Non-Commercial License.

mailto:m.j.ritzen@tue.nl


54 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

connection to the grid to cope with seasonal differences (AgentschapNL, 2012; EU, 2010; Torcellini,
Pless, Deru, & Crawley, 2006). Reaching the target of nearly zero energy depends only on improving
the energy efficiency in the operational phase of the building. This requires adding material to the
building for thermal insulation, building services and energy generation products. Consequently, the
realization of a less energy consuming built environment is largely depending on an increase of
material consumption, and collateral increase of construction material extraction, resulting in an
increase of the material related impact compared to the energy related impact (Ramesh, Prakash,
& Shukla, 2010). Worldwide, extraction of construction minerals increased between 1995 and 2005
with 30% (Bruckner et al., 2012).
Besides improvement the energy performance of new buildings, improvement of the energy per-

formance of existing buildings is increasingly being realized, amongst others in the office sector.
The Dutch office market, consisting of 52.2 million square meters, had a vacancy percentage of

14.6% in 2012 (Zadelhoff, 2013), corresponding with 7.62 million square meters. As the market sit-
uation of office buildings in the Netherlands is not in equilibrium, renters have a wide variety of
real estate to choose from, and are in the position to select offices with a high energy perfor-
mance. The average energy label of the 10% of offices in the Netherlands that have an energy
label is E (AgentschapNL, 2010a). This label corresponds with an operational energy performance of
1.49GJ/m2·a for heating and cooling, lighting and hot tap water. Besides this market development,
the Dutch government agreed that the Dutch government itself, responsible for around 20% of office
space occupation in 2010 (AgentschapNL, 2010b), only rents offices with minimum energy label C
since 2010, which results in a higher energy performance of buildings (AgentschapNL, 2010a). Already
a number of NGO’s and companies have joined this agreement, and it is expected that more orga-
nizations will join this government agreement in the framework of Corporate Social Responsibility
(CSR). As a result, many offices are renovated to improve their energy label to a minimum of C. In
these renovations, the façade is often replaced to improve the operational energy performance of
the building.
Currently, a wide range of tools is available to calculate the operational energy performance of

buildings, such as the Dutch standard Energy Performance Calculation Program ((NEN), 2010), and
VABI 114 (VABI, 2013).

Fig. 1. Energy label distribution in the Dutch office market 2010 (AgentschapNL, 2010a).



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 55

But assessment tools, used to measure the environmental impact of buildings, should take both
the energy aspect and the material aspect in such a way into account that the necessary insight is
created in the total burden. Examples of these tools are BREEAM, LEED and the Dutch Greencalc+. In
these tools, aspects such as energy and materials are combined with aspects such as management
through a weighted combination of indicators (Häkkinen, 2012).
These tools have a number of advantages, such as the distinction in the level of sustainability of a

building compared to other buildings, providing a communication tool, encouraging stakeholders to
define sustainability requirements, and providing a vehicle for policymaking (Tran, 2009).
However, in these tools energy and materials account for different shares in total building per-

formance outcomes and different categories are applied. The different categories are divided into
different subcategories and the grading of the subcategories depends on different quantitative and
qualitative parameters. The parameters are based on performance and evaluation, while different
system boundaries are used and different levels of detail are applied. Resulting in an outcome in
which the level of sustainability for comparable buildings differs due do the different aspects and
weighting (Häkkinen, 2012). According to Iwaro et al, the measurements and the weights that should
be given to the criteria are unresolved issues (Iwaro, Mwasha, Williams, & Zico, 2014). The outcomes
in the end might show how the energy and/or material situation has improved, but create a dilemma
with regard to what the connection is between the outcome of the assessment tool and the actual
environmental impact of the building.
Considering the material aspect, it is often only translated in embodied energy: the amount of

energy necessary to process raw materials, modify materials and transport materials. Energy, embod-
ied in buildings, may account for up to 60% of total life cycle energy (Dixit, Fernández-Solı́s, Lavy, &
Culp, 2012). Façades may account of up to 26% of total building embodied energy (Thormark, 2007;
Yohanis & Norton, 2002). The embodied energy in materials can be seen as a ‘rebound effect’ of
energy performance improvement, and has in current practice a negative impact on the calculated
operational energy performance improvement in household heating and cooling (Herring, 2009). The
same can be expected in office buildings. By calculating material consumption using only the embod-
ied energy, the operational energy aspect and the material aspect are translated in a corresponding
quantity; energy. For instance, Belgian residential low energy buildings with a primary energy con-
sumption for heating of ca. 900MJ/m3 building volume over 30 years have a total embodied energy of
1400MJ/m3 building volume over 30 years, which is higher than the energy consumption for heating
(Verbeeck & Hens, 2010).
For embodied energy calculations various definitions, methodologies and system boundaries are

used (Dixit et al., 2012). An example of the latter is that there is a distinction between methodologies
in which only the amount of fossil based energy is part of the calculation as it is ‘added’ to the
product, and methodologies in which the total amount of embodied energy, both fossil based and
renewable based, which comes from ‘natural sources’ such as the sun, is calculated. Besides the
different calculation methodologies, most results have uncertainties due to temporal, spatial and
technical circumstances (location, weather, societal and energy generation), which are in many cases
not shown in databases underlying the calculation tools (Dixit et al., 2012). A third aspect of embodied
energy calculations is the varying system boundary of the calculation.
All these aspects have resulted in databases which face the problem of incomparability and variation

(Dixit et al., 2012). Besides these considerations, all embodied energy methods do not take into
account the actual availability of resources, both renewable and non-renewable. As the extraction
of construction materials increased significantly, it is worth exploring a method to be able to assess



56 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

energy and materials equally. Due to the increase of material consumption and due to the associated
increase of raw materials extraction more and more land is needed, with a negative impact on
amongst others ecological systems, biodiversity and the reflectiveness of Earth (planetary albedo).
In addition, raw materials which are necessary for the production of the building materials, such as
copper, do not have an infinite stock. Besides land use required for extracting raw materials, there is
also land needed for generating non-renewable and renewable energy to convert the raw materials
in building materials or components and transportation of these building materials and components.
As we have a limited amount of land and potential productivity of this land, it seems logical to base
our consumption pattern on the land available for production and extraction of (building) materials,
generation of energy, water production and food production.
In future, land necessary to produce renewable energy might compete with land necessary for food

production and material production, which may lead to other choices in the design and realization
of buildings (Rovers, de Flander, Gommans, & Broers, 2011). Consequently, sustainability needs to
be based on what can be generated and consumed in equilibrium within the system, implying an
indicator based on the carrying capacity necessary to materialize and operate a function, instead of on
impact calculations without any relation with the system itself (Rovers, 2010). The carrying capacity
is the maximum persistently supportable load of a system (Catton Jr, 1986), and can be indicated
by the amount of land necessary to sustain the functioning of the system and the time this land is
necessary, embodied land.
To calculate the embodied land, an assessment tool called MAXergy is under development (Rovers,

2010). The embodied land of a product (in m2·year) indicates the amount of land needed for the
extraction of raw materials, the growth of materials, the generation of power, the recuperation of
land, etc. in the Dutch situation (Rovers, 2010, 2011; V. Rovers et al., 2011). The aim of the tool is
to generate insight in the interaction of the energy and material aspect in buildings and relate the
total impact of these impacts to the carrying capacity. In the methodology section this tool is further
explained.
In this research, the relation between building environmental assessment tool outcomes and actual

environmental impact is investigated. The energy and material aspects of three office façade reno-
vation solutions are compared by using four different assessment tools in relation to the carrying
capacity. A comparison is made between the situation before and after renovation of a south facing
simulated office space with the different façade renovation solutions, covering the energy use of the
building (operational energy), materials of the façade (embodied energy) and the related land use
(embodied land) and compared with the outcome of a generic tool. Based on the comparison, a façade
renovation solution with lowest environmental impact on carrying capacity has been calculated.

2. Methodology

The environmental impacts of three façade renovation solutions, realized in the Netherlands, have
been investigated through a comparison of the outcomes of four different assessment tools before
and after renovation.
For this research, a south orientated office space has been simulated in front of which different

façade renovation solutions have been placed. The south facing façade has been selected because it
is the building component which has the biggest effect on the annual cooling and heating load of a
building in the Netherlands. The simulated space has a width of 8m, a length of 8m and a height of



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 57

7m. The simulated space consists of office spaces divided over two floors, because office spaces are
the most relevant spaces in the buildings and the design of one of the selected projects is based on
two floors. The selection of the three office façade renovation projects was based on availability and
completeness of data and drawings and the sustainability ambitions in Greencalc+.

Fig. 2. Impression of the selected façade renovation solution of the DHV office building (source: vd Meijden).

Fig. 3. Impression of the selected façade renovation solution of the WNF office building (source: vd Meijden).



58 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

Fig. 4. Impression of the selected façade renovation solution of the Central Post office building (source: vd Meijden).

The following façade renovation solutions were selected:

• DHV office, Amersfoort; renovation during which the façade was totally replaced and the interior
was preserved largely.

• WNF office, Zeist; renovation during which the façade was totally replaced and the building was
partially demolished, stripped and refurbished.

• Central Post, Rotterdam; renovation of an existing post office, during which the façade was
partially replaced.

For each simulated space the same technical installations were applied for a relevant comparison of
the influence of the façades on assessment tool outcomes. In all cases, only the material and energy
aspect of the façade was taken into account. Building structure and architecture, services, lighting,
interior components, economic, societal and user behaviour were out of the scope of this research
to generate in depth insight in the relation between the energy and the material aspect, although
these other aspects might have a substantial influence on building performance and impact (Stephan,
Crawford, & de Myttenaere, 2012). For the calculations of the office façades a technical lifetime of 30
years (Ebbert, 2010) was chosen as reference. Energy and material aspects related to the pre-building
phase as well related to the re-use phase and demolition phase were out of the scope of this research.
In Table 1 an overview is given of materials used in the different façade renovation solutions.

Table 1
Overview of materials applied in the selected office façade renovation solutions

DHV office aluminium curtain wall; double pane argon filled glazing
WNF office wooden curtain wall, triple pane krypton filled glazing
Central Post office aluminium curtain wall; double pane argon filled glazing



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 59

The office façade renovation solution with lowest environmental impact in terms of embodied land
has been further optimized using MAXergy, because this tool relates most closely to carrying capacity
and assesses both the material and energy aspect and its interaction without weighting.
The following assessment tools/databases have been applied: VABI, ICE, Greencalc+, and MAXergy

and will be further introduced in the following sections.

2.1. VABI 114

VABI 114 (VABI, 2013) is a dynamic building simulation program in which the annual heating and
cooling load in MJ can be calculated. VABI 114 generates in depth insight in the operational energy
aspect in relation to the indoor climate. VABI 114 complies with national and international standards
BRL 9501, BESTEST, EDR according to ISSO 54 and ASHRAE standard 140. In this research, the program
has been applied to calculate the operational energy demand of the simulated space with different
façades before and after renovation. The program only takes operational energy into account. Other
aspects, such as embodied energy, are not embedded in the program nor is the interaction between
different aspects.

2.2. ICE database

In this research, the “Inventory of Carbon & Energy” (ICE) database of the University of Bath
(Hammond, 2008) is selected to calculate the embodied energy of the different façade renova-
tion solutions before and after renovation. The ICE database has been selected because the data
corresponds most closely to the Dutch situation. The ICE database is an inventory of the embod-
ied energy of materials data, originating from Life Cycle Analyses (LCA’s), books and papers. In
the embodied energy calculation there is no interaction with other aspects such as operational
energy.

2.3. GreenCalc+ program

GreenCalc+ (Greencalc+, 2013) expresses the sustainability of a building in an environmental index.
The environmental index of a building (Milieu Index Gebouw - MIG) is based on a comparison of the
environmental costs of material consumption, energy consumption, and water consumption with the
environmental costs of a standard Dutch building realized in 1990. Greencalc+ has been applied to
determine the overall building sustainability after renovation. By translating all aspects into one cost
aspect they can be combined to one generic outcome and thus compared to other buildings. The
determination of environmental costs of materials is based on CML-2, the LCA method developed by
the University of Leiden, in combination with the Eco-indicator ’99 method and the TWIN-model. The
method of Müller-Wenk is used for the determination of transportation related noise disturbance.
The determination of environmental costs is based on the Dutch standards NEN 2916:2004 and NEN
5128:2004, complying with the Dutch standard Energy Performance Calculation. This calculation is
through a LCA translated into environmental costs. For office buildings, the determination of water
consumption is calculated with the Dutch ‘Water Performance Standardisation’. This calculation is
through a LCA translated into environmental costs. Although the impact of user mobility is calculated
in Greencalc+, it is not part of the generic outcome. The user mobility is determined for office buildings



60 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

Fig. 5. Floor plan of the investigated simulated south facing office space.

Fig. 6. Section of the investigated simulated south facing office space.

by a calculation in an adapted version of the software program VPL-KISS (Greencalc+, 2013). Between
the different aspects in Greencalc+ there is no interaction or interrelation.
The standard reference building from 1990 has a value of 100 MIG. When a building is more

sustainable than the reference building from 1990, then the value becomes above 100 MIG. Build-
ings with a MIG-value below 100 are less sustainable than a building realized in 1990. Although
this tool indicates the relative improvement of environmental impact of a building compared with
other buildings and with a building in 1990, it does not indicate clearly the actual impact on the
environment.



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 61

2.4. MAXergy

MAXergy is a sustainability tool which expresses the energy and material impact of a project in the
same physical quantity: Embodied land. Embodied land is the amount of space and time necessary to
fulfil the energy and the material demand for a certain function in a certain environment. Embodied
land is expressed in m2·year (Rovers, 2011). The embodied land of the different façade renovation
solutions before and after renovation has been calculated using MAXergy. The total embodied land
(EL) of a product is calculated using several databases as input the amount of new and recycled
materials. The total embodied land calculation can be divided into direct embodied land (land and
time required for the creation of a raw material), indirect embodied land (embodied energy converted
into land and time) and operational energy (converted into land and time).
The embodied land for a building consists of three components, a. EL building, b. EL materials and

c. EL operational energy, as indicated in Fig. 7.
a. EL building indicates the land occupied by the building during its lifespan itself and can be directly

derived from the design drawings in m2.

Fig. 7. Schematic overview of the proposed embodied land calculation method for a combined environmental assessment
of energy and materials in the built environment.



62 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

b. EL for materials consists of two impacts: The primary impact indicates the time·land required to
generate, produce and transport the material itself. The primary impact consists of the direct EL for
material generation, and indirect EL for material production and transportation.

1. The direct primary EL is calculated using a harvest database in which harvest/m2 are collected,
depending on the origin of the material. The indirect primary EL is based on the ICE embodied
energy database and through energy generation surface calculated (solar or fossil based) (Ham-
mond, 2008). The input needed to calculate both direct and indirect primary EL is the mass of
the building material (kg) and energy generating device efficiency.

2. The secondary impact indicates the time·land required to generate and produce the techniques
and installations necessary to generate the materials; e.g. the photovoltaic panels required
to generate the necessary embodied energy. The tertiary impact and other possible relevant
impacts, such as operational transportation energy, are not taken into account (Stephan, Craw-
ford, & de Myttenaere, 2013). The input needed to calculate the secondary EL is both the mass
of materials used in the installations (kg) and installation efficiency (W/m2).

c. EL operational energy consists of the land necessary to generate the energy using solar energy
(PV/ solar thermal) or fossil resources and the EL necessary for the generation, production and
transportation of the materials used for the energy generating devices.
These tools and databases were selected to generate in depth insight in the operational energy and

material aspect (VABI 114 and ICE database), and to be able to compare these results with a widely
used generic tool in the Netherlands (Greencalc+) of which the data of all cases was available, and
to be able to relate this to the carrying capacity (MAXergy).

3. Results

In the following section, the calculated results of the different applied assessment tools/databases;
VABI 114, ICE database, Greencalc+ and MAXergy are presented. In Section 3.2.1 the results of VABI
114 and the ICE database are combined.

3.1. VABI 114

Figure 8 shows the results of the annual cooling and heating load of the simulated office space with
different façade solutions before and after the renovation, calculated with VABI 114. The heating and
cooling load of all three cases after the renovation is similar. The cooling load of the investigated south
orientated space is in all buildings the largest energy factor both before and after the renovation.
The renovation of the façade has mainly impact on the heat load of the building, which is strongly
reduced after the renovation. This is achieved by increasing the Rc value of the façade through the
application of materials with higher values of thermal insulation and the application of double pane
argon filled glazing or triple pane krypton filled glazing.

3.2. ICE database

Figure 9 shows the results of all embodied energy calculations of the different façade solutions
before and after the renovation. The embodied energy required for the façades of the DHV office



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 63

Fig. 8. Annual operational energy load consisting of heating and cooling of the simulated south facing office space with
façade solutions before and after renovation.

Fig. 9. Total embodied energy of the façade solutions before and after renovation.

and the WNF office after the renovation is many times higher than the embodied energy of the
façades before the renovation. After renovation, the DHV office has a new aluminium curtain wall
with double pane argon filled glazing and the WNF office has new wooden curtain wall with triple



64 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

Fig. 10. Total energy performance of the simulated south facing office space with façade solutions before and after
renovation, over 30 years.

pane krypton filled glazing. The embodied energy required for the new façade of the Central Post
building is relatively small compared to that of the other buildings. This is because this façade was
only partly replaced and remained largely unchanged. Furthermore, the embodied energy required
for the original façade was already very high due to the large amount of the materials applied, such as
concrete and steel. The existing aluminium façade with single glazing is replaced by a new aluminium
façade with double pane argon filled glazing.

3.2.1. Combination of VABI 114 and ICE database
In Fig. 10 the results of total energy consumption calculations are shown (operational energy of

the simulated office space and the embodied energy of the façade) before and after the renovation,
for a total technical lifetime of 30 years. The results indicate that, for the investigated south facing
office space, the cooling load has the largest energy impact, both before and after the renovation.
It also shows that the heat load of the office space has decreased significantly after the renovation,
which is the result of the improved thermal properties of the façades after the renovation. To achieve
these improved thermal properties more embodied energy is required for the façades. In general the
embodied energy of the façades increases after renovation, but the cooling load remains the largest
energy demand for this south facing office space.

3.3. GreenCalc+

The results of all renovation projects in Table 2 show a final score above 200 and all projects score
both in the field of energy performance and material consumption an A, which is good. In the results
there is no difference between the various projects in the field of energy performance and material



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 65

Table 2
Greencalc+ score of all renovation projects

DHV office WNF office Central Post office

Material A A A
Energy A A A
Water E F G
Total 239 269 252

Fig. 11. Total embodied land in m2 of the simulated south facing office space with different façade solutions before and
after renovation based on fossil fuels, over 30 years.

consumption. The WNF office has the highest total score, because the building generates energy with
photovoltaic (PV) panels.

3.4. MAXergy

Figure 11 show the calculated embodied land of façade materials and the calculated embodied
land of operational energy of the simulated office space when all energy required for the operational
energy is based on fossil fuels. Fossil fuels have a significant larger EL that renewable fuels due to the
large amount of land and large span of time necessary to generate these fuels (R. Rovers et al., 2011).
Due to this, the embodied land of the operational energy is the determining factor compared with
the embodied energy for the materials of the façade. Only the results of the WNF façade solution
show a different situation where the material use is the determining factor. This is because after the
renovation operational energy in this building is generated by solar energy.
Figure 12 shows the embodied land calculations of the simulated office space with different façade

solutions before and after renovation, over 30 years, when all energy is generated by solar energy
(solar panels and solar collectors). In this calculation, the total embodied land for all solutions is
much smaller than with a similar calculation using fossil fuels, due to the large time·land impact to



66 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

Fig. 12. Total embodied land in m2 of the simulated south facing office space with different façade solutions before and
after renovation based on solar energy, over 30 years.

generate fossil fuels. Secondly, the embodied land for the façade materials is much greater than the
embodied land for the operational energy. The embodied land of the operational energy is in most
cases negligible compared to the embodied land of the façade materials.
The results show that the WNF office façade solution after renovation scores very good in com-

parison with the other façades. This façade consists mainly of wood, a natural material with low
embodied energy. Natural (bio-based) materials score very well in the embodied land calculation,
because these materials can grow back naturally by themselves, so a closed-loop system is created
without adding energy.
A closed-loop system for the materials is created when a material that is used as a building product

has grown back within the lifetime of the façade, and all energy to realize the building product
has been regenerated. The aluminium, concrete and steel that are used in the DHV and the Central
Post Office façade solutions are not bio-based and cannot grow back. These materials are however
recyclable and partially reusable. The recycling percentages of these materials are not 100%, for
aluminium it is for instance 94% (Haas, 2002). According to the MAXergy calculation a lot of energy
is needed to win back the non-recycled percentage of these materials.

4. Calculation of a façade renovation solution with lowest environmental impact on carrying
capacity

Based on the results presented in section 3, the WNF façade solution has been further investigated
and its environmental impact has been further minimized using MAXergy. As indicated in the preceding
sections, using only energy related calculations or using a generic assessment tool does not offer a
comprehensive carrying capacity based indicator of the environmental impact of a building. Analysis
of the materials applied in the WNF façade solution (Fig. 13) shows that most of the embodied land
of the façade originates from non bio-based materials, such as steel and aluminium.



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 67

Based on this analysis a comparison has been made between four façade solution versions to
investigate the embodied land minimisation as a result of the interaction of the material and energy
aspect. In Fig. 14 an overview is given of these versions:

a. The façade after renovation with a certain amount of material related EL, mainly due to non-
renewable materials, and a certain amount of operational energy related EL;

b. Minimisation of material related EL while maintaining the same operational energy related EL
resulting in a façade in which the actual openings are maintained and thermal insulation is
maintained, but all materials are 100% bio-based.

c. Minimisation of material related EL, resulting in a façade consisting of a plywood sheet and no
openings.

d. Minimisation of operational energy related EL with high insulation values for the opaque façade
components (Rc=10m2·K/W).

Fig. 13. embodied land of different materials in the WNF façade solution in m2·year.

Fig. 14. Total embodied land in m2 of the simulated south facing office space with different façade solution versions based
on solar energy, over 30 years.



68 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

Fig. 15. Picture of the realized WNF façade renovation (source: vd Meijden).

In all versions the embodied land of the materials is still larger than the embodied land of the
operational energy, indicating the importance of material consumption in this assessment method.
Even when the façade consists of only a minimal amount of bio-based materials (only a 30mm
plywood sheet), the embodied land required for the operational energy is small.
Within the boundaries of the Dutch Building Regulation, a minimisation of environmental impact

of the façade renovation solution has been investigated. The Dutch Building Regulations indicate the
following for this office façade calculation:

• Insulation value for opaque façade parts Rc 3.5m2 K/W.
• U value transparent façade parts U 2.2W/K·m2.
• 2m2 transparent façade surface per office floor.
Within these boundaries a maximum use of bio-based materials is investigated. Non bio-based

materials, like metals, need to be recycled as much as possible. The façade design consists for 93% of
bio-based materials, in which the metal components have been replaced by fibre-reinforced compos-
ites. Even the design of window placing is realized without metal components (Fig. 16). Resulting in a
façade solution that needs a total of 304m2 embodied land for a lifespan of 30 years, which is a reduc-
tion of 70% compared to the actual WNF façade renovation solution. In addition, in the design is taken
into account that the building components are easy to separate, increasing the possibilities for re-use
and recycling. The collateral effect of this minimization of embodied land is a solution with disputable
architectural quality, compared to the realized WNF office façade renovation design (Fig. 16).

5. Conclusions and discussion

Based on the comparison of the simulated south facing office with different façade renovation
solutions and the calculation of a façade renovation solution with minimal environmental impact



M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands 69

Fig. 16. Picture of the calculated office façade renovation with minimal embodied land (source: vd Meijden).

based on carrying capacity, the following conclusions concerning operational energy performance,
material performance and the related embodied land are drawn.

• This research indicates that in the simulated cases operational energy efficient façade renovations
result in a decrease of operational energy and an increase of embodied energy in the façade.
Assessment tools based either on one aspect such as operational energy or on only energy
related aspects or resulting in a generic outcome do not generate insight to lower the actual
total environmental impact.

• In all cases, the cooling load is the largest energy part of total energy demand both before and
after the renovation and the embodied energy of the façades is a small portion of the total
energy demand, over a lifespan of 30 years, considering only a south facing façade. These results
would presumably be different when the complete building would be taken into account and
when other orientations of the façade would be investigated.

• Not only the amount of materials but also the choice of materials determines the embodied
energy and embodied land of the façade.

• In the case of the WNF façade solution, the building itself generates after the actual renovation
to a high extend its own energy through photovoltaic (PV) panels on the roof. If in this case
the operational energy would not be included in the calculation and the PV panels would be
included in the material calculation, the total energy consumption of the building would consist
solely of embodied energy. Material consumption would in this case be the determining factor
in environmental impact.

• The embodied land calculations based on fossil fuels show in almost all cases that the opera-
tional energy is the determining factor compared to materials. An exception is the WNF office
façade solution after the renovation because in this case the operational energy of the building
is generated on site. In this situation, the material aspect becomes the determining factor in
environmental impact.



70 M. Ritzen et al. / Comparison and development of sustainable office façade renovation solutions in the Netherlands

• The calculated office façade renovation solution indicates that the amount of materials and
the choice of materials determine the environmental impact in nearly all situations. Bio-based
materials, such as wood, score very well in this calculation because the low amount of embodied
energy and renewability. Further research is suggested to compare the façade versions using
other tools, and base façade versions on these tools.

• It can be concluded that in a combination of embodied and operational energy based on fossil
fuels, the material aspect determines the environmental impact in the case of NZEB’s, such
as the WNF building, emphasizing a tool in which the material aspect and energy aspect are
non-weighted assessed, and the MAXergy tool offers this possibility.

Based on this research project, the following conclusions concerning the MAXergy tool are drawn
to suggest further research in this direction.

• The energy related embodied land calculation in MAXergy is based on the surface of solar panels
and solar collectors, which is necessary for generating electricity and heat. The results of the
embodied land calculations are therefore highly dependent on the efficiency of the solar panels
and solar boilers used for this.

• Operational energy is in an increasing number of buildings generated with renewable sources,
but the majority of embodied energy is not. Therefore, a comparison is made between the land
use by means of fossil energy and solar energy. Further research into impact by using the current
energy mix (fossil fuels, nuclear and renewable energy) is recommended to generate insight in
the actual energy related embodied land of materials.

• An important part of the MAXergy calculation is the recovery of raw materials such as metals. In
many cases this is the decisive factor for the final result. For the recovery of metals for example
a method is chosen, in which metal particles are filtered from seawater. This includes a number
of assumptions. Further research should be done on the recovery of metal particles.

• As the MAXergy tool aims at relating the combination of material consumption and energy
performance of a building to the carrying capacity of a system it offers the possibility to generate
insight in building performance from a perspective related to our planet. But as the tool is
based on existing embodied energy data, the same discussions concerning availability of data,
the bandwidth of results, etc. are relevant and further research should be conducted in order to
generate more reliable outcomes related to the carrying capacity.

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