04cB6 study PLEA2005.doc

PLEA2005 - The 22nd
Conference on Passive and Low Energy Architecture. Beirut, Lebanon, 13-16 November 2005 1/6
Study of vernacular architecture in Spanish areas of
extreme climate for the selection of bioclimatic
design strategies.
Silvia Martín1 and Ignacio Cañas1
1
Departamento de Construcción y Vías Rurales,
Escuela Técnica Superior de Ingenieros Agrónomos,
Universidad Politécnica de Madrid, Madrid, Spain
ABSTRACT: In this research work we turn to vernacular architecture in order to analyze the design
strategies and then to be able to translate them to new buildings. From the climatic data of 76
Spanish weather stations, some areas of extreme climate were selected. Five zones of hot climate
as well as five zones of cold climate were analyzed in this work. Therefore, the most important
parameter in the local architecture is the protection againstthe harsh clim ate. The design strategies
found in local architecture from these areas was studied. The aim of this study is to check those
design strategies found in vernacular architecture that can be translated to modern constructions in
order to reduce the energy consumption and maintain the local architectural pattern.
Conference Topic: Vernacular Architecture: Sustainability Lessons from the Past
Keywords: vernacular architecture, passive elements, bioclimatic charts
1. INTRODUCTION
The passive use of natural resources has been
present in people and animals behaviour along the
time. From basic activities as the recollection of food
or the search of protection, to developed practices as
the use of local building materials, or natural energy
such us the wind for the navigation and water course
for milling grains.
Along the history the relationship between climate
and architecture has always been close. There is a
dependencybetween construction materials,systems
and techniques, building design and local climate.
Vernacular architecture usually shows a proper
relationship between climate, human needs and
sustainable construction, therefore it could be
considered as the primitive bioclimatic architecture.
Spain is a country located in the south – west part
of the European continent. Due to its situation,
between latitudes 36ºand 43º N, Spain belongs to the
temperate climate area. The solar height is quite
variable along the year, being very high in summer
and low in winter. This causes two different thermal
seasons: summer that can be warm to very hot and
winter that cab be cool to cold. In general terms,
annual temperature variations are high,so the design
strategies should carry out the double task of
protecting the building against hot in summer and
cold in winter.
Furthermore, due to the geographic situation of
Spain, we can find five different areas with a specific
climate:
- Oceanic climate: belonging to Galicia and the
Cantabrian costs, in this area the temperature is soft
and the precipitations are abundant.
- Continental climate:belonging to the inner areas
of the Peninsula, this area has cold winters and hot
summers.
- Mediterranean climate: belonging to the
Mediterranean costs, the summers are hot and dry
and the winters are soft. The precipitations
accumulate in autumn. The solar radiation is very
high in summer.
- Mountainous climate: belonging to Pirineos, the
Central System and the Penibetica mountain chain.
The winters are cold and long and the precipitations
are abundant.
- Subtropical climate, belonging to Canary
Islands, the temperature is soft all the year and the
precipitations are scarce.
Instead of the existence of various sub-climates,
the most representative are the continental and the
Mediterranean types.
In popular architecture the climate is simply one
more of the various forces (whether social, cultural,
economic, defensive or religious, or involving the
availability of materials, technical and constructive
resources) thatgenerate the forms of architecture [1].
The more severe is the climate, the more influence it
has on the vernacular architectural forms. That is the
reason for the selection of regions of extreme climate
in Spain.
The Spanish Institute of Meteorology [2] have
climatic data for 80 complete weather stations all
around Spain. In this work we use the available
climatic information to select 10 regions, 5 regions of

PLEA2005 - The 22nd
cold winters and 5 regions of hot summers. The
climatic parameters used were: monthly average,
maximum and minimum temperatures. A climatic
index was used for the selection of the regions:
IChot summer = 0.4 tM + 0.6 TM
ICcold winter = 0.4 tm + 0.6 Tm
where tM is the annual average of monthly
maximum temperatures,TM is the average maximum
temperature of the hottest month, tm is the annual
average of monthlyminimum temperatures and Tm is
the average minimum temperature of the coldest
month.
The 5 regions of hot summers are those with the
highest IChot summer index, while the 5 regions of cold
winters are those with the lowest ICcold winter index. In
table 1 the selected localities and its climatic
parameters are shown, and in figure 1 the localities
are placed in the Spanish map of solar radiation.
Table I: Climatic values for the 10 selected
localities. Temperatures are in degree C and altitude
above sea level in metres.
Place tM TM tm Tm IC Altitude
Hot summers regions
Cordoba 24.5 36.2 10.4 4.2 31.5 123
Sevilla 24.7 35.1 11.7 5.5 30.9 34
Jaen 22.3 34.6 11.4 4.6 29.7 580
Toledo 21.8 34.4 9.2 0.9 29.4 516
Jerez 23.6 33.0 11.6 6.0 29.2 27
Cold winters region
Molina 17.1 28.4 2.9 -2.7 -0.5 1063
Soria 16.5 28.0 4.4 -1.4 0.9 1082
Teruel 18.1 29.7 5.0 -1.7 1.0 902
Burgos 20.9 32.3 11.0 4.9 1.1 890
León 16.5 27.6 5.0 -0.9 1.5 916
Figure 1: Map of solar radiation ofSpain, pointed out
the selected localities of hot summers and cold
winters.
As can be seen in table 1 and figure 1, the regions
of hot summers are place in the middle South of
Spain, with altitudes lower than 600 m above sea
level. On the other hand, the regions of cold winters
are placed in the middle North of Spain, where the
solar radiation is lower and the altitude is higher.
In the next section the bioclimatic chart for the hot
summers and cold winters regions are studied in
order to assess the design strategies more suitable
for each zone. Later the traditional architecture of the
selected regions is analyzed to observe how people
make use of natural resources and energy to achieve
comfort conditions inside their buildings. Finally, we
discuss about how those design strategies can be
translated to modern architecture.
2. BIOCLIMATIC DESIGN STRATEGIES.
With the available climatic information ofeach locality,
Givoni´s bioclimatic charts were carried outin order to
know the design strategies more suitable for each
region.
2.1. Regions of hot summers.
The five selected localities are characterized by hot
summers and mild winters. The temperature and
solar radiation in these regions are high in summer.
As a result,building design should aim at minimising
heat gain indoors so that users of these spaces can
have adequate thermal comfort. Figure 2 shows the
bioclimatic chart for Cordoba.
Figure 2: Givoni´s bioclimatic chart for Cordoba.
In the figure it can be observed that the main
problem in these regions is the summer period (May
to September). In winter the good use of solar
radiation makes the indoor conditions comfortable.
But in summer there is a significant problem of
overheating. The design strategies proposed to
mitigate the high temperature are: 1) use of high
thermal mass envelopes,2) use of high thermal mass
envelopes in addition to night ventilation, 3) use of
natural ventilation and 4) solar protection.
2.2. Regions of cold winters.
Figure 3 shows the bioclimatic chart of Molina de
Aragon.
The temperature in these regions is cold in winter, so
building design should aim at minimising heat loss
and maximizing solar gains.

PLEA2005 - The 22nd
As can be seen there is no significant problems of
overheating in summer, however winter conditions
are far from the comfort zone.
Figure 3: Givoni´s bioclimatic chart for Molina.
3. VERNACULAR ARCHITECTURE.
In this section we show the results of the review of
vernacular architecture´s references [3, 4, 5] in order
to analyze how people in ancient times and with little
technique built their houses in good response to the
climate. More information about the relationship
between bioclimatic and vernacular Spanish
architecture can be found in [6].
3.1. Regions of hot summers.
Most of the selected localities are placed in the
region called Andalusia.Some typical solutions found
in traditional architecture in relation to the climate are
shown in figures 4 to 6.
Figure 4: Patio full of vegetation in a traditional house
in Jerez. Source: Flores, 1974 [3].
Figure 5: Underground dwellings in Toledo. Source:
Flores, 1974 [3].
Figure 6: Traditional house in Sevilla. Source: Flores,
1974 [3].
The main characteristic thatshould be pointed out
as the most spread in Andalusian vernacular
architecture is the white colour of the walls. Oktay [7]
stated that in hot climates a white or light coloured
roof, in combination with well placed shaded trees,
can lower the building´s cooling load by 30%. Givoni
[8] analyzed the effect of envelope´s colour. The
results of monitoring on test cells showed that the
colour of the external surfaces of the walls and roofs
has a tremendous effect on the impact of the sun on
the building and on the indoor temperature of un-
conditioned buildings, particularly in regions where
solar intensityis high. The difference in the maximum
external surface temperature between a white roof
and a black one in a desert in the summer can be 30
to 40ºC. Most houses in Andalusia have the roof
made of tiles, but there is a type of house – the cubic
house- with flat roofs painted white.
Another spread characteristic is the small size of
the housing, due to the Muslim influence. As Flores
[3] says:“we know that Muslim dwellings were small,
grouped in narrow streets, with the entrance door as
the only opening in the facade”. The previous
statement shows the importance of compactness in
the vernacular architecture of Andalusia.
The patio is another typical element found in
houses from the South of Spain (fig. 4) [9]. They are
opened to the sky or partially shaded by grapevines.
This element provides protection against hot.
Sometimes they have fountains and vegetation to
promote evaporative cooling and provide shade. A
well designed courtyard provides cool to the rooms
during the day when the ambienttemperature is high.
In addition, the courtyard works equally well in cold
seasons.
In some areas of hot summers, the underground
dwellings appear as a housing system (fig. 5). Today
mostof them are abandoned.Underground dwellings
utilize the thermal storage of the soil to achieve

PLEA2005 - The 22nd
cooling in different ways: 1) damping out interior daily
temperature swings, 2) delaying temperature
extremes and 3) using the almost stable temperature
of soil at depth, which means that it is lower than
outdoor temperature in summer and higher in winter.
This provides direct passive conductive cooling for
the building.
The openings in these regions are scarce and
small to avoid the solar radiation penetration.
Provided that the outdoor temperature is higher than
indoors, heat gain through windows per unit area, is
much higher than through walls or the roof. In
addition,in these regions, sunlight is very intense, so
large windows can cause glare discomfort, even
more, taking into account that most envelopes are
painted white. However, in Seville, the size of
windows is great in relation to its climate. Although
they are usuallyprotected by blinds and lattices which
control the daylight and heat from outside (fig. 6). On
the other hand, the great size of the openings,
provides high night ventilation to cool the building. In
fact, good ventilation is a very important practice of
climate control in regions of hot summers during
nights and evenings.Ventilation can increase the rate
of cooling of the building´ structural mass. It should be
remembered that in high mass buildings, maximum
temperatures occur in the evenings.
3.2. Regions of cold winters.
The main characteristic of traditional buildings in
these regions is the use of massive walls, with
thickness of about 50 cm. The passive solar
architecture is supported on three main practices: 1)
collection of natural energy, 2) storage and 3)
distribution. The high thermal mass of the exterior
envelope contributes to the energy storage. However,
it is necessaryto collectthe solar energy first. Various
materials were used to construct the walls – mainly
stone and earth - , it depends on the local availability.
As well as being well adapted to the climate,
vernacular architecture is a good example of
sustainable construction. The use of local materials
and techniques has social and environmental
advantages. Local population can develop its skills,
so this is a method to fix population in rural and low
dense areas. In addition, materials transportation is
reduced so life cycle energy consumption is lower
than in modern construction.
Next figures show some typical housing in these
regions.
Figure 7: Traditional housing in Burgos. Source
Ponga & Rodriguez, 2000 [5].
Figure 8: “Pinariega” house in Soria. Source: Flores,
1974 [3].
Figure 9: Houses with porch in Soria. Source: Flores,
1974 [3].
Although there is a need of solar gains to heat the
building,the openings are very small in the observed
examples (fig.7). Windows are the main elements for
collecting solar radiation but they are also the
weakest points from the aspect of heat loss. In
ancient times, when the glass technique was no so
developed, people tried to reduce the heat losses by
avoiding the openings in the facades.
The need of insulation against harsh climatic
conditions, in a time when thermal insulation
materials did not exist, was supplied by different
methods: 1) thick walls to increase the thermal
resistance,2) small openings to reduce air tightness,
3) use of natural resources, 4) adapted living
practices. The use of natural resources can be seen
in the layout of some traditional houses. In some of
them,people shared the house with the cattle, so the
heat dissipated by animals was used to increase the
indoor temperature. The kitchen was an important
part of the house. It was large and it was located in
the middle of the house or in the north part. The
chimney was lighted on during almost all the winter.
In some cold regions, the straw wastes were used to
heat the building by means of a hypocaust called
“gloria”. This heating system developed by Romans,
is still in use in some localities. The straw and other
field products were stored in the upper floor of the
house, just under the roof. In this way, these
materials served as thermal insulation, because the
roof was constructed only to avoid water infiltration.
Another common practice in traditional
architecture of these regions is the construction of

PLEA2005 - The 22nd
semi-open spaces as porches or galleries (fig. 9).
They are spaces protected from the rain in winters
and autumns and from the sun in the short but hot
summers.
In addition, underground dwellings were found in
some regions of cold winters, but they are less
common than in regions of hot summers.
The orientation of the villages in these regions
usuallyis facing the sun,protected from cold winds by
natural barriers such as hills or trees.
4. LESSONS FROM THE PAST.
Our popular architecture may well be the kind
which can best teach us today how to assimilate the
bioclimatic approach in the practice of architectural
design.The solutions found in vernacular architecture
may be use as a lesson and a source of inspiration,
not as a model to copy.
Some forms of traditional buildings – the
underground dwelling – are being abandoned as it is
perceived that they reflect underdevelopment and
poverty. The meaning ofthis study is not: “go again to
the cave or live with the cattle” but make good use of
the thermal inertia and stable soil temperature for
climate control of buildings in regions where the
underground construction proved along the time to be
suitable to the environment.
Another aspect of vernacular architecture that can
be used as a model is the behaviour of people. In
ancient times, people lived in a good relation to the
house. They knew how to use the windows – closing
them during the day and opening during the night in
summer - in order to control the indoor environment.
Nowadays, we are very used to the mechanical
systems and those good practices are being lost.
Figure 10: Traditional house made of stone, with a
sunspace.
Figure 11: Rehabilitated rural house made of earth
and stone.
In figures 10 and 11 two examples of rehabilitated
traditional houses located in regions of cold winters
are shown. The envelope of high thermal mass was
used to store the collected solar heatbut in each case
the south façade was renovated to increase the
glazing surface. In winter, the energy consumption is
smaller than in a conventional house and in summer if
the glazing surface is shaded, the comfort conditions
are achieved with no energy use.
Figure 12: New block of houses in Andalusia,
following bioclimatic design strategies. Source:
AA.VV, 1997 [10].
Figure 12 shows a new block of houses built in
Andalusia. The architects took into account the local
traditional architecture in the design stage. Therefore
the new buildings are well adapted to the landscape
as well as to the climate. The envelope was painted
white to reflect the solar radiation.The openings were
provided with overhangs and shutters for shading in
summer. The building materials have high thermal
mass.In addition,solar collectors were installed in the
South orientation to provide hot water to the building.
As the choice of colour does not involve extra cost, a
reflective colour of the building envelope is a good
architectural climatic control strategy, and it is one of
the mostcost-effective way to minimize the building´s
heat load in summer.
This section is only an example of how traditional
architecture can serve as a model for modern
architecture, well adapted to the climate.
CONCLUSION
The way to achieve the premises of sustainable
construction can be found in the vernacular
architecture, which respects the local characteristics
of a region, such as the climatic conditions, the
construction materials and solutions, the culture and
the tradition.
The observation of traditional elements allows us
understanding the vernacular architecture as a way to
respect the local features.
The good way to use the vernacular architecture
is by translating the design elements to the present.
Some of the design elements maybe used in modern
buildings but other are not suitable because living
standards todaydiffer significantlyfrom ancienttimes.

PLEA2005 - The 22nd
REFERENCES
[1] H. Coch. Renewable and Sustainable Energy
Reviews, 2, (1998), 67 -87.
[2] National Institute of Meteorology, www.inm.es
[3] C. Flores. Arquitectura popular española. Aguilar
SA. España. (1974).
[4] Feduchi. Itinerarios por la Arquitectura Popular.
Blume, España. (1984).
[5] J.C. Ponga Mayo, M.A. Rodríguez Rodríguez,
Arquitectura popular en las comarcas de Castilla y
León. Junta de Castilla y León. Consejería de
Educación y Cultura. España. (2000).
[6] I. Cañas, S. Martín. Building and Environment, 39,
(2004), 1477 – 1495.
[7] D. Oktay. Building and Environment, 37, (2002),
1003 – 1012.
[8] B. Givoni. Passive and low energy cooling of
buildings. Van Nostrand Reinhold. (1994).
[9] C.L. Hinrichs, Proc. 6th
International PLEA
Conference, Porto, Portugal (1988), 53.
[10] AA.VV. Arquitectura y clima en Andalucia.
Manual de diseño. Junta de Andalucia. España.
(1997).

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