ESTRATEGIAS BIOCLIMATICAS

1. 1
Strategies of bioclimatic design used in traditional agrarian buildings of Spain.
Cañas Guerrero, Ignacio; Martín Ocaña, Silvia
Departamento de Construcción y Vías Rurales. Escuela Técnica Superior de Ingenieros
Agrónomos. Universidad Politécnica de Madrid. Avda. Complutense s/n. 28040. Madrid.
Tel: 913365767, Fax: 913365625, mail: icanas@cvr.etsia.upm.es
Abstract
The objective of this study is to establish bioclimatic design strategies using the
Spanish agrarian popular architecture as a model. The bioclimatic strategies
have different purposes depending on the dominant regional climatic factor.
Spain is located within the zone of temperate climate, in particular within the
Mediterranean type. Nevertheless and in spite of their small extension, many
types of climatic areas with widely varying characteristics exists in Spain. In
this article the climatic classification proposed by the Building Technical Code
is employed. The agrarian popular architecture has responded to these different
climates applying different design strategies. By observing cases of popular
constructions, suggestions about the passive design strategies suitable for each
climatic zone are made.
Keywords: Spanish agrarian architecture, Mediterranean climate
1. Introduction.
The aim of this study is to suggest bioclimatic design strategies for the different areas of
Spain. This article is based on the climatic classification proposed by the “Building
Technical Code” that is going to take effect at an early date, replacing the current Building
Basic Regulation NBE-CT-79. The climatic classification of the Building Technical Code
divides Spain into twelve zones made by the combination of the summer and winter
conditions.
The suggestion of the suitable bioclimatic design strategies for each zone is carried out
taking into account cases of popular constructions found in bibliography. Agrarian popular
architecture has met the different climatic conditions by the implementation of design
strategies. Many years ago when the modern systems of environmental control did not
exist, man was able to found the means for the protection against inclement weather as well
as for taking advantages of natural energy. In this article the popular construction is
presented as the beginning of bioclimatic architecture. The design strategies employed in
this type of constructions are passive strategies, it is to say that these strategies do not need
the use of additional energy.
2. The climatic zones of Spain based on the Building Technical Code.
Spain is a country located in the south – west part of the European continent. It is situated
in the temperate area, between latitudes 43º47´24´´ N (Estaca de Bares) and 36º00´3´´ (
Punta de Tarifa), and between longitudes 7º00´29´´ E (Cape of Creus) and 5º36´40´´ O
(Cape of Tourinan).
The area of Spain is 580.850 km2
. It borders on Cantabrian Sea, France and Andorra to the
North, on Mediterranean Sea to the East, on Mediterranean Sea and Atlantic Ocean to the
South and on Portugal and Atlantic Ocean to the West.

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Due to its situation Spain belongs to the temperate climate area, although it is said that
Spain has a Mediterranean climate (this term is applied to the areas surrounding the
Mediterranean Sea).
Nowadays, there is no climatic classification of Spain focused on the bioclimatic
architecture. In this study the climatic classification of the Building Technical Code for the
calculation of the required thermal insulation is used.
The Building Technical Code is a group of regulations that the buildings should observe for
improving the quality. It establishes the minimum requirements related to the acoustic,
thermal and structural conditions of the building materials as well as of the installations
used in buildings. This study centres on the part of the Building Technical Code related to
the requirements for energy savings. Like in the current Building Standard (NBE-CT-79),
the upper limit of the thermal transmission coefficient depends on the climatic conditions
of the place where the building will be constructed. There are differences between the
climatic classification proposed in both Regulations. The NBE-CT-79 establishes 5
climatic zones: A,B,C,D and E1
by using different levels of degree/days during the heating
season. In the other hand, the Building Technical Code establishes 12 climatic zones by
combining the heating and cooling season conditions of the main Spanish cities (see table
1). The climatic zones are set through the climatic severities2
, there is a climatic severity
for winter and another for summer (see figure 1)
A4 B4 C4
A3 B3 C3 D3
C2 D2
Summer
climatic
severity
C1 D1 E1
Winter climatic severity
Figure 1: Climatic areas.
Winter climatic severity: A=0.3; B= 0.3 - 0.6; C=0.6 – 0.95; D= 0.95 – 1.3; E > 1.3
Summer climatic severity: zone 1= 0.6; zone 2= 0.6 – 0.9; zone 3= 0.9 – 1.25; zone 4> 1.25
The hottest areas are the ones with lowest winter climatic severity and highest summer
climatic severity, while the coldest areas are the ones with highest winter climatic severity
and lowest summer climatic severity.
The table 1 shows the climatic classification of all the Spanish provincial capitals.
3. Spanish popular architecture.
In order to suggest some passive design strategies for the different climatic areas defined
above, we turned to the main references about Spanish popular construction (Flores, 1974;
Claret Rubira, 1976; Feduchi, 1984; Benito, 1998; Ponga, J.C; Rodríguez, M.A, 2000). The
relationship between different construction typologies and prevailing climatic conditions
was analyzed.
The way of establishing the sustainable construction is easy: to restore the values from
traditional architecture and to make good use of the technologic advances. The features of
1
Zone A <= 400 annual degree/day; Zone B: from 401 to 800 annual degree/day; Zone C: from 801 to 1300
annual degree/day; Zone D: from 1301 to 1800 annual degree/day, and Zone E > 1800 annual degree/day. The
degree/days are calculated on the base 15-15 Celsius degree according to the Regulation UNE:24.046.
2
The climatic severity is a meteorological parameter which combines the influence of the air temperature and
the solar radiation, so that in two locations whose climatic severity is the same, the same building will have
the same energy requirements.

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different world climates have formed the indigenous architectural shapes for each different
geographical location.
Table 1: Climatic classification of the Spanish provincial capitals.
Referenceheight(m)
Drop between the town and the provincial
capital (m)
Provincialcapital
Province

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Besides the adaptation to the prevailing climatic conditions, there are other parameters
influencing the vernacular architectural shapes, as: topography, availability of building
materials, customs, familiar organization, and way of living of different people.
In Spain, due to its wide climatic variation, lot of traditional architectural typologies appear.
The basis of this article is the study of specific popular buildings that make use of certain
construction elements for the “protection against” or the “use of” the prevailing climatic
factors. The most important references about vernacular architecture have been revised,
focusing on the cases where the author mentions clearly the relationship between some
concrete constructive element and the climate of the place. From the whole cases found in
the bibliography, only the ones with design strategies directly related to the climatic
parameters employed in the climatic classification of the Building Technical Code
(temperature and solar radiation) were selected. Eighty nine cases of popular construction
with graphical information were analyzed and grouped by climatic zones (see table 2).
Table 2: Studied cases in each climatic zone.
Climatic zone Number of cases
A4 3
B4 9
C4 4
A3 13
B3 6
C3 2
D3 2
C2 0
D2 10
C1 5
D1 6
E1 29
The constructive elements found in the analyzed cases try to achieve the next objectives:
• Protection against solar radiation: It is needed when the air temperature is higher
than 21º C (Olgyay, 1998), although this value varies according to the location of
the building and its final use. The constructive elements employed for the protection
against solar radiation try to avoid the overheating and the excessive natural lighting
inside the building. The solar protectors can be fixed or mobile, horizontal or
vertical, and interior or exterior. They are usually placed on the façade openings, but
in areas where solar radiation is extremely high the structural parts of the buildings
are also in the shadow. The constructive elements most usually employed to provide
shadow to the building are: wing walls, portals, window shutters, window blinds,
curtains, lattices, trees and other vegetation. In addition, there is another system
whose task is to reflect the solar radiation, so it should be considered as a strategy of
protection against solar radiation, it is the use of light colors for painting the façade.
• Use of solar radiation: Three stages are required: capture, store and distribution of
solar energy. The elements designed for the passive use of solar energy can carry
out the three stages or only some of them, in this case another part of the building
will develop the rest.
• High thermal inertia: This strategy is used in areas where the oscillation of
temperature is high during the day and during the year, as much in cold climates as

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in hot ones. The thermal inertia causes a gap and a softening of the exterior
temperature wave. An example of the use of high thermal inertia is the underground
construction.
• Protection against cold: This objective is achieved by means of constructive
elements that insulate the building from the exterior environment, as window
shutters. Although there is other elements that do not protect the building against
cold, they are characteristic of cold climates as the steep pitched roofs for avoiding
the accumulation of snow.
• Shape and location of the building: The compact shapes reduce the contact with the
exterior environment, so they are found in areas of extreme climates. On the
contrary, with extended shapes the exposed surface is higher so the contact with the
exterior environment is higher and the possibility of ventilation is increased. On the
other hand, the selection of the location of settlements has been an important task
since ancient times, the best places are the ones protected from the inclemency of
the weather and rich in natural resources.
4. Results.
The analysis carried out in this article shows that taking the vernacular architecture as the
model of bioclimatic architecture, it is only possible to make suggestions for areas wider
than the ones proposed by the Building Technical Code (CTE).
The results are showed in the next tables:
Table 3: Results
Bioclimatic
area
CTE
areas
NBE-
CT-79
areas
Recommended Design Strategies
A4
B4
A
A3Hot zone
B3
B
Protection against solar radiation: small openings, facades of light colors,
courtyards, underground dwellings, lengthening of the wing walls, lattices
and other mechanisms of solar protection. Elements for the capture of rain
water for domestic use and as a cooling mechanism.
D2
D1Cold zone
E1
E
Compact shapes and close to the ground for the reduction of the contact
with the exterior environment. Location of settlements on protected places
as the end of a valley. Predominance of the wall opposite the openings.
When there is suntraps, they are protected by wood boards or other
elements. Pitched roofs encouraging the loss of the snow.
Transitional
zone 1
C1 D In this zone some elements found in the cold zone are kept. Predominance
of suntraps for the capture of solar radiation in winter.
Transitional
zone 2
C4 This zone is very similar to the hot zone but some elements for the
heating of the building are present.
C3Transitional
zone 3 D3
C This zone is characterized by its temperate climate. Elements for
achieving opposite purposes could be found in this zone.
Table 4: Bioclimatic zones based on the classification of the Building Technical Code.
Transitional
zone 2
Hot climate
Transitional zone 3
No data
Summer
climatic
severity
Transitional
zone 1
Cold climate
Winter climatic severity

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In the following figures it is showed a specific vernacular building for each bioclimatic
area.
Alcaracejos (Cordoba), hot climate Lucillo (Leon), cold climate
Rada (Santander), transitional zone 1 Garrovillas (Caceres), transitional zone 2
Illana (Guadalajara), transitional zone 3
5. Conclusions.
The proposal of bioclimatic design strategies taking the vernacular architecture as a model
only allows to make a distinction between wide areas where there are important changes in
the constructive typologies. Naturally, the majority of cases of popular buildings in which
there is a clear relationship between some particular constructive element and the climate

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match with areas where the weather is hard. Popular architecture give answer to social,
cultural and economic situation of the location, as well as to the dominant climate and to
the suitability of building materials. In areas where the climate is harsh (cold or hot), the
climatic parameter is more important than the rest so the relationship between climate and
construction is more clear. In the transitional zones generalizations can not be made,
however the observation of the prevailing constructive typology in the area will help in the
establishment of some design elements for the integration of the construction on the
environment.
Acknowledgements
The authors wish to express their appreciation to the Ministry of Science and Technology
of Spain within the Project of Investigation PB8-0720 “Aproximación a una metodología
de reutilización de construcciones rurales” for their financial support.
References
1. Benito, F. La arquitectura tradicional de Castilla y León. Volúmenes 1 y 2. Junta de
Castilla y León. Consejería de Medio Ambiente y Ordenación del Territorio. 1998.
2. Claret Rubira, J. Detalles de Arquitectura Popular Española. Editorial Gustavo Gili,
S.A. 1976.
3. Feduchi, L. Itinerarios por la Arquitectura Popular. Barcelona: Blume. 1984.
4. Flores, C. (1974). Arquitectura popular española. Editorial Aguilar S.A. Madrid.
5. Olgyay, V. (1998). Arquitectura y clima. Manual de diseño bioclimático para
arquitectos y urbanistas. Editorial Gustavo Gili, SA. Barcelona, España.
6. Ponga Mayo, J.C; Rodríguez Rodríguez, M.A. (2000). Arquitectura popular en las
comarcas de Castilla y León. Junta de Castilla y León, Consejería de Educación y Cultura.