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Thermal map of urban space, www.pedroborjamunoz-arquitecto.es, modification: cut



Vitruvio
International 
journal of 
Architecture 
Technology and 
Sustainability
Volume 1 Is 2

1

ABSTRACT

1 Università degli Studi “G. d’Annunzio” di Chieti-Pescara, Dipartimento di Architettura 

Today, the cities need to increase energy efficiency, reduce polluting emissions and achieve a sufficient level 
of sustainability. The urban microclimate plays an important role on the buildings energy consumption and the 
feeling of comfort in the spaces. The microclimate parameters are of central importance for the activities that 
are carried out in the open spaces and to a large extent determine the use. The responses to the microclimate 
may be unconscious but very often result in a differentiated use of open spaces just as function of the different 
climatic conditions. For this reason, the aim of this work is focused on the environmental parameters and on 
the methodology of analysis aiming at the establishment of bioclimatic strategies for buildings on the basis of 
morpho-type of the components of the geometries and surface quality of the materials used in urban spaces and 
in function of the consequent microclimatic conditions obtained.

KEYWORDS
urban microclimate, comfort, energy efficiency, bioclimatic design

Urban microclimate parameters for 

buildings energy strategies

Michele Lepore1 

http://dx.doi.org/10.4995/vitruvio-ijats.2016.6944



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1. ENVIRONMENTAL DESIGN 
    IN URBAN CONTEXT

The environmental parameters that affect the outside 
comfort thermal conditions, although similar to those 
relating to the interior spaces, are characterized by 
a greater and more complex variability. Therefore, 
because of this variability and the broad diversification 
of activities in which people are involved, there 
have been so far few attempts to understand the 
comfort conditions on the outside but especially 
as the climatic effects outside could have an impact 
on the technologies of the building envelop and 
consequently on the conditions of comfort within the 
confined spaces.
One of the objectives of environmental design in urban 
contexts is the creation of districts with comfortable 
open spaces. The microclimate parameters are 
therefore of central importance for the activities that 
are carried out in the open and to a large extent 
determine the use.  For this reason, understand the 
richness of the microclimatic features into urban 
spaces outside, and the implications in terms of 
comfort for the people who use them, opens up new 
possibilities for the design of these spaces both in 
terms of new interventions, both in the retraining of 
existing agglomerations.
The study of the districts must be configured through 
a series of analysis developed in successive stages of 
deepening the spatial characteristics, technological 
and environmental concerns both the settlements 
scale, is a typological both technological. 
In particular: 

analysis of geographical context and climate;
analysis of the morphological characteristics to 
the building scale;
analysis of the conditions of comfort outside in 
the residential settlements;
analysis of the technological characteristics of the 
building envelop;
the system building-plant.

1.1  METHODOLOGY

The methodology is based on an evaluation of 
the climatic conditions and the thermal comfort in 
different conditions. The climatic parameters are 
obtained by parametric evaluations and computer 
simulations based on fluid dynamics, thermodynamics 
and irradiation in an urban environment using 
numeric approach. The great advantage in the use of 
computing systems is the ability to evaluate different 
scenarios.
From a careful analysis on the external climate 
conditions and thermal comfort in the immediate 
neighborhood of the residential settlements, you 
want to locate the appropriate technologies to the 
redevelopment of the individual units by improving the 
parameters of thermal comfort inside of the dwellings 
themselves. 
Primary objective, therefore, is the search for a 
methodology to assess the quality of the microclimatic 
public space, that is repeatable in cases and different 
places with verifying the possible influences of the 
external climate on the overall energy efficiency of 
the settlement and the consequent identification of 
appropriate technologies that are not based only on 
climate class referring to the locality. 
Specific objectives:

Analyze urban spaces according to the physical 
aspects environmental, through a system of 
indicators that characterize study areas.
Define indicators for analysis of the aspects 
of microclimatic space, able to put in relation 
the environmental conditions to the comfort of 
users in order to define certain minimum quality 
requirements.
The identification of a methodology for the 
calculation capable of assessing the quality 
microclimates of public space in an objective 
manner and replicable in other cases in other 
places, evaluating specific software for the 
simulation of the phenomena that occur in the 
urban space outside.



Vitruvio
International 
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Technology and 
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2. URBAN MICROCLIMATE

Urban areas have particular climatic condition as 
results of complex urban microclimates, where many 
factors come into play. It is important to describe how 
and why the urban climate differs from the climatic 
condition of the surrounding rural areas.
Urban and industrial growth has caused significant 
changes in the radiant balance of the urban spaces, 
the convective heat exchange between the ground 
and its buildings, the air flowing above the urban area 
and the heat generation within the city. 
The main consequence is differences in value of air 
temperature and in wind conditions between urban 
and rural areas.
Air temperature in dense urban areas are higher then 
temperatures in the surrounding countryside. 
This different is known as the “urban heat-island effect 
and characterised almost every city or town in the 
world. The heat that is absorbed during the day by 
all urban constructions (buildings, roads, etc.) is re-
emitted after sunset, and the greatest temperature 
differences are observed during the night. 
Furthermore, additional heat is given by all human 
heat sources.
Urban space creates unique climatic conditions called 
the urban microclimate. 
The first consideration is that it is possible associate 
the urban morphology to microclimatic behaviour, 

or in other words, to define a microclimatic 
patterns characteristic for each urban typology. 
The second one, as mentioned before, is based on 
the observation that the environmental conditions 
influence the use of urban outdoors spaces. If it is 
possible to quantify the thermal comfort through the 
study of climatic parameters, the modification of the 
urban microclimate will affects the thermal comfort of 
people. 
The confirmation of the two assumptions leads to 
the definition of the third hypothesis: it is possible 
to mitigate the impact of the microclimate through 
the modification of the constructed urban space, 
and consequently, improve citizens thermal comfort 
conditions. 
The specific objectives to achieve this aims are: 

1. Define a system of indicators to characterize and 
describe the physical and environmental aspects 
of study areas. These indicators should be able 
to describe the current situation and guide 
refurbishment project. 

2. Define indicators for the analysis of microclimatic 
aspects of outdoor spaces, able to establish a 
relationship with environment conditions and 
comfort sensation, in order to find a minimum 
quality target. 

3. Establish a calculation methodology able to 
evaluate the microclimatic quality and comfort 
of public space in an objective way and suitable 
for the application on other cases and other 
locations. 

4. Elaborate the guidelines for the refurbishment of 
built spaces from the perspective of microclimatic 
and environmental improvement of urban areas.

5. Evaluate specific software for the simulation of 
climatic phenomena which occur in outdoor 
urban space.

Figure 1.

Heat island effect



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2.1  ANALYSIS OF THERMAL COMFORT

The environmental performance relative to the 
urban space in its entirety is the description of the 
thermohygrometric behavior mixed as a result of the 
combination of morphological parameters, matter 
and microclimate in relation to a specific use. This 
type of description it is useful to make it through the 
use of the indicator of comfort, because the indicator 
contains in itself the mixer of the parameters in the 
game. It is important to use for comfort indicators in 
relation to environmental requirements, whether they 
are expressed by users or that are unaware.
To assess the environmental performance of an 
urban space as a whole there can be no limit to the 
analysis of the microclimatic conditions in point, as it 
cannot be limited to evaluate the various parameters 
individually. A good result is obtained by providing 
the areal distribution of the comfort conditions 
throughout the area. The maps of comfort represent 
an evaluation of the existing conditions or a check of 
the design choices. 
From the observation of these maps you can get 
further information on the project, which relate in 
particular to the placement of the urban equipment 
that allow the carrying out of activities compatible 
with the environmental performance in the given time 
interval. 
From the evaluation of the performance in the 
moment in which they were not congruent with the 
environmental requirements of users, we derive 
guidance on specific requirements that define the 
project and characterize it.

2.2  THE ANALYTIC INDICATORS

The analytic indicators are calculated by following the 
path of the heat flow from the human metabolism to 
the environment vice versa whereas the variations of 
this flow in relation to the variation of environmental 
factors. They derive from the equation of energy 
balance based on models which consider all the 
climatic parameters significant. 
These models use a balance equation of heat with a 

models more or less simplified to evaluate the mean 
radiant temperature. 
The thermal comfort can be described with the use of 
certain indices:

WBGT takes only climatic data into account such 
as air temperature, radiant heat, solar radiation, 
air movement.
PMV has solid base in the indoor environment but 
takes into account relevant factors and the affect 
thermal sensation.
PET and out SET are for outdoor environments.

PET does not calculate individual parameters and out 
SET takes personal parameters for one standard type 
of person.
The ISO 7730 defines thermal conditions of outdoor 
environment in which the probability of negative vote 
is minimised. 
The index “Predicted Mean Vote - PMV” and the index 
“Predicted Percentage Dissatisfied - PPD” are based 
on ISO 7730 and are taking into account the climatic 
parameters in conjunction with the relevant factors 
affecting the thermal sensation of each respondent 
(clothing, metabolic rate, eating or drinking). 
The PMV-index describes the comfort levels with the 
prediction of the possible votes taking into account 
meteorological factor in combination with human 
biometeorology values. The value of the index is 
between -7 which means too cold and +7 with means 
hot and the value of zero represent the comfort 
vote. With this scale the closets the value of the PMV 
index is to 0 the better are the comfort levels for the 
human. Still this index cannot take into account the 
psychological factors described and that is the why 
there are certain differences of the value of the PMV 
and the real votes on the field surveys (Fanger, 1992).
Common microclimatic data with the PMV (Predicted 
Mean Vote) require two other indexes: PET 
(Physiologically Equivalent Temperature) and out SET 
(Standard Effective Temperature). All those thermal 
indices are well documented and include important 
meteorological and thermo-physiological parameters 
so as to define the total comfort. 
The scale that are measured is in °C but the 



Vitruvio
International 
journal of 
Architecture 
Technology and 
Sustainability
Volume 1 Is 2

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parameters required in the model are both climatic (air 
temperature, humidity, radiation environment, wind 
speed and direction) but also physical characteristics 
of every interviewee (age, sex, weight, height, clothes, 
metabolism rate). 
A full application of these thermal indices on the energy 
balance of the human body gives detailed information 
about the effect of the thermal environment on every 
human (Van Hoof, 2010).
In the case of areas with a great variety of spaces, 
ranging from dense vegetation and extensive 
shading, to areas completely exposed to the sun and 
wind, the data from the meteorological station cannot 
adequately represent the microclimatic conditions in 
the site. Comfort models should be able to approach 
the microscale for design purposes, distinguishing 

Figure 2.

Relation between PMV and 
PPD, and other sensation 
thermal indices, as found by 
Fanger

between sunny and shaded areas, or areas protected 
and exposed to the wind, which ultimately directly 
affects thermal comfort conditions in a given space. It 
is therefore of value to devise a way to include design 
related parameters into environmental data.
Identifying simplified correction factors between 
locally measured conditions and those of the nearby 
meteorological station, during the field surveys, can 
reflect the modification of the microclimate. 
Such correction factors can be used as modification 
parameters for design oriented comfort models, 
reflecting the microscale, thus of value to designers. 
In this context, vegetation can affect the microclimate 
in a number of ways, reducing air temperature 
compared to hard surfaces, shading and providing 
wind protection (Cres, 2014).



6

Figure 3.

Givoni bioclimatic chart for 
comfort evaluation

2.3  WIND

One of the most important factors influencing 
pedestrian comfort conditions in outdoor open spaces 
is the wind. Wind environment is difficult to foresee 
and control because it is influenced by a number of 
global, regional and local factors. On a global scale 
wind comes from air moving from high-pressure 
areas to low-pressure areas. The wind velocity and 
direction produced by the global weather systems 
are subsequently influenced by the regional and 
local landscape typology. It is therefore important to 
understand that there can be large differences in the 
wind environment from one part of a city to another 
or even on micro scale from one part of a space to 
another.  Wind is not a constant phenomenon. It 
varies momentously in direction and strength (wind 

gusts) and variations can be seasonal or annual.
The direct effects of the wind can be divided into two 
main categories, mechanical and thermal effects: 

mechanical effects of wind can be felt with wind 
velocities above 4-5 m.s-1. Above 10m.s-1 it will 
be unpleasant to walk and above 15m.s-1 there is 
a direct risk of accidents;
for thermal effects the 5 m.s-1 comfort criteria 
used presumed that people will adapt their 
behaviour and clothing level to the season.

It should be noted that depending on climate a certain 
level of wind could be regarded as undesirable or 
desirable. In cold climates wind will almost always 
decrease outdoor comfort conditions, whereas the 
opposite is the case in hot climates (Ghiaus, 2007).



Vitruvio
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2.4  THE IMPACT OF MATERIALS

In order to reduce the heat island intensity, the first 
method is to design the external environment in 
order to minimise solar heat gains. In general, this 
can be achieved by increasing the solar reflectivity 
of construction material surfaces and reducing te 
insulation of susceptible structures. During this 
procedure, the albedo of the various materials and 
surface is a crucial factor (Santamouris, 2006).
The albedo of a surface is defined as the reflected 
solar radiation divided by the incident solar radiation. 
Urban areas and cities are characterized, in general 
by a relatively reduced effective albedo. This is due 
to the greater absorption of solar radiation by urban 
construction materials and multiple reflection inside 
urban canyons. Thus, the optical characteristics of 
used materials have an important impact - their 
albedo-to-solar radiation and emissivity of long-
wave radiation being the key parameters. High 
albedo material reduce the amount of solar radiation 
absorbed through building envelopes and urban 
structures, and in this way keep their surfaces cooler. 
Respectively, materials with high emissivity are good 
emitters of long-wave energy and release the energy 
that has been absorbed as short-wave radiation. In this 
way their surface temperature is lower and contributes 
to the reduction of ambient temperatures through the 
mechanism of heat convection (Santamouris, 2001).

Figure 4.

Interaction between the wind 
and buildings

3. ENERGY AUDITS 
   TO SCALE SETTLEMENTS 

The first action is constituted by the stripping "thermal" 
of the isolate to assess separately the environmental 
quality of the context both under the profile of 
thermo-hygrometric (temperatures, levels of relative 
humidity) and is reported to the climate wellness, 
evaluating the levels of both thermal sensation that 
the index of feeling on the part of the inhabitants 
of the settlement building. These parameters were 
evaluated by comparing two calculation methods: 
the ASV (Guidelines Rurors) and PMV (Fanger). The 
main critical points found to scale settlements are of 
type "physiological", linked to the levels of thermal 
sensation on the part of the inhabitants of the district 
refers to the outdoor spaces. In the case of study 
(Monticchio in the province of L'Aquila) to which 
has been applied this methodology, comparing the 
two methods of calculating the ASV and PMV show, 
both coincidence of results both while negotiating 
on climatic conditions in winter have highlighted 
deficiencies in the summer period, giving as a result a 
feeling of "hot", abnormal done in a mountain resort. 

Figure 5.

Ground reflected irradiance 
with varying Albedo 



8

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A careful analysis of the impact the sun-air has 
highlighted the objective relationship between 
settlement and environmental context and climate. 
In the preliminary stages, the quality checks have the 
aim to assess the relationship between climate and 
the morphology of the settlement with respect to the 
orientation to the compactness of the intervention, 
in addition to the climatic parameters specific to the 
site. In detail dismantling “thermal” of settlements 
and identification of external surfaces deemed 
more burdensome from the point of view of energy 
consumption and comfort of the occupants. 
For verification of environmental performance related 
to the state of fact, the first step was the “thermal 
decomposition” of the agglomerate, associating to 
each element a thermal role as for example:
 

buildings = thermal mass; 
green spaces private loggias, etc. = microclimatic 
niches;
spaces paved impermeable, paved, etc. = thermal 
amplifiers;
garages, garages, box, cellars, etc. = buffer space.

3.2 ANALYSIS OF THE CONDITIONS EXTERNAL 
COMFORT IN RESIDENTIAL SETTLEMENTS.

The microclimate parameters are of central importance 
for the activities that are carried out in the open and to 
a large extent determine the use. 
The responses to the microclimate may be 
unconscious but very often result in a differentiated 
use of open spaces according to the different climatic 
conditions. The typological dimension, diagnosis 
has focused on performance verification residual 
thermal building system-installations of buildings, 
highlighting the poor quality of the thermal insulation 
and energy management in period both winter and 
summer in addition to an overall inefficiency of the 
system engineering. All homes are in class G.
Also, verification of environmental quality inner is 
consistent with that carried out the urban scale or, in 

summer levels are obtained significant discomfort. The 
first results show that a pure physiological approach is 
inadequate in characterizing the conditions of comfort 
outdoors and an understanding of the dynamics of 
the human parameter is required in the design of 
spaces for public use. The thermal environment is of 
fundamental importance because they influence the 
persons to use these spaces, but the psychological 
adaptation (choice available, environmental 
stimulation, thermal history, expectations) is equally 
important. The responses induced by microclimate 
may be unaware, but they often translate into a 
different use of the urban space as the climatic 
conditions vary. Best microclimatic conditions in turn 
have important implications for the development 
of the city. Through the control of the sources of 
discomfort, are favored sedentary activities, as well 
as the use of public transport, movement on foot and 
the use of the bicycle. The same image of the city can 
benefit from the quality of the external spaces. 
In San Francisco, the planning laws stipulate that 
new buildings must be placed in such a way as 
not to promote air motions over 5 m/s, 90% of the 
hours of light, in areas where people can sit. The 
shading of whole streets is achievable with the shafts 
with the advantage to obtain a cooling through 
evapotranspiration through the leaves. - always in 
the case of Monticchio, diagnosis has focused on 
performance verification residual thermal building 
system-installations of buildings, highlighting the 
poor quality to the thermal insulation and to energy 
management in the winter period in addition to an 
overall inefficiency of the system engineering. All 
homes are in class G.



Vitruvio
International 
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Volume 1 Is 2

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Figure 6.

Case Study of Monticchio 
(AQ), study of the impact of 
solar radiation on the external 
surfaces of buildings



10

REFERENCES

AA.VV. Progetto RUROS, progettare gli spazi aperti nell’ambiente 
urbano: un approccio bioclimatico, CRES (Centre for Renewable 
Energy Sources, Department of Buildings), 2004

Fanger P. O., Thermal comfort. MacGraw-Hill, 1972.

Ghiaus C. and Allard F., Natural ventilation in the urban environment, 
Earthscan, London 2007.

Mayer, E. A new correlation between predicted mean votes (PMV) 
and predicted percentages of dissatisfied (PPD). In: J. E. Woods, D. 
T. Grimsrud and N. Boschi, editors. Proc Healthy Buildings/IAQ ’97, 
Bethesda, 2, 189- 194 (1997) 

Santamouris M., Environmental design of urban buildings, an 
integrated approach, Earthscan, London, 2006.

Santamouris M., Energy and climate in the urban built environment, 
James&James, London, 2001.

Van Hoof J., Mazej M., Hensen J. L. M. Thermal comfort: research 
and practice in Frontiers in Bioscience 15, 765-788, January 1, 2010.

4.  CONCLUSIONS

This study is conducted in several different steps. 
The final goal was to define the basic parameters 
that affect the comfort levels on open urban spaces 
and to implement a design strategies for building 
refurbishment project. The basic hypothesis is that the 
comfort condition in outdoor spaces comes as a result 
of the interaction of all the microclimate parameters 
together. For the effectiveness of this methodology, 
further analysis are needed for full representation 
of climatic behaviour of each seasonal period. This 
would assist the choice of buildings energy strategies 
through the design of outdoor spaces and eventually 
the use of these spaces, by allowing for different 
activities to be carried out by inhabitants.



Vitruvio
International 
journal of 
Architecture 
Technology and 
Sustainability
Volume 1 Is 2

11