1. Bioclimatic Potentialities of
Contemporary Housing Estates
Architecture, Energy and Comfort in Algeria
Kheira Tabet Aoul
Architect, PhD
University of Science and Technology of Oran, Algeria
responsive design a minimum thermal comfort, as well as
Abstract an opening to various climatic and cultural contexts.
There is a recent but growing interest in developing
countries to integrate environmental aspects in the
building sector. This paper stems from former concern Algeria: Background Information
with thermal comfort and energy efficiency in “modern” Algeria, on the Mediterranean coast is the second largest
housing schemes erected all over Algeria regardless of its country in Africa with 2,382 760 square kilometres
climatic diversity. First, a review of the climatic (Figure1). It stretches from latitude 19o to 36o North, and
conditions is presented along the vernacular architectural as such experiences a diversity of topography and
solutions it generated. Then, an investigation is carried climates.
out to test the thermal behaviour of self-built houses in
contemporary housing estates and investigates their
improvement by passive means. Simulations, using a
thermal software (DEROB) were used.
Introduction
The issue of thermal comfort and energy savings in the
building sector of Algeria has yet to be properly
addressed. The initial high needs in terms of housing, as
in most developing countries, are still mainly expressed
quantitatively, with hardly any consideration of the
aftermath on traditional construction methods, cultural
and social context, environmental comfort or energy
efficiency. The result was the rapid growth of
internationally styled buildings and infrastructures,
reflecting Western technology, introduced into an Figure 1: Location of Algeria in the African continent
essentially traditional environment. The consequences of
this rupture in the housing sector are multiple. In terms of The population, with one of the highest birth rate, is
environmental comfort, bad design, poor control and a expected to reach 32 millions by the beginning of the new
complete disregard of the climatic conditions have century. Over 52% of all Algerians are now living in
resulted in many substandard houses, where heating and urban settlements and mainly concentrated in its northern
cooling are a prerequisite to achieve thermal comfort. coastal part. The desert, which accounts for 4/5 of its total
Furthermore, in the past governmental energy price area, is sparsely inhabited.
control has led to unrealistically low energy costs, Petroleum and natural gas on the other hand are
discouraging a rational energy use. This attitude is now principally found in the Sahara. They are Algeria’s most
changing due to high inflation of energy costs over the important mineral resources, its leading exports and main
last decade. In this context, urban planners, architects and source of income. The drop in international oil prices
engineers have a key role to play. during the 1980s had a negative impact on the socialist
This brief review and investigation undertaken here is a planned economy and contributed partially to its reversal
contribution towards a better understanding of the to an open market one. This meant cuts in all subsidis ed
climatic and design requirements to achieve through a sectors and resulted in a high inflation rate. Building and
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2. Kheira Tabet Aoul
energy sectors were the most affected and as a result their mainly sheep and goat herders, experience equally
prices inflated greatly. rigorous winters and hot summers. Building design
In terms of energy use, 35% of all energy is used in strategy has to equally address both heating and cooling
buildings of the residential and tertiary sectors for space requirements, with a high mass and winter sun exposure.
heating and cooling, domestic hot water, lighting etc. The The southern slope or the Saharan atlas, a broken series
potential of energy savings in both sectors (residential and of mountain ranges and massifs is also a semi-arid area
tertiary) is estimated up to 10% and 15.6% for and is used chiefly for pasturing livestock. Here, winters
respectively the year 2000 and 2020 (Guellouz, K. 1992). are short but cold and summers are long, very hot and dry.
These savings may only be achieved through the planning Similar design strategies apply here with an emphasis on
of efficient saving strategies in general; a sound summer protection.
controlled building design and the establishment of Finally, the largest part of the country, the Sahara, has
adequate building regulations (Tabet Aoul, K, 1996). short cold winters, particularly at night and long, very hot
and dry summers. Sandstorms are frequent year round and
rainfall is scarce. To achieve comfort by passive means
Climate and the Design Comfort only is rather difficult. However, contribution would be
Requirements made through high inertia of walls and roof, maximum
solar radiation control through shading devices as well as
Algeria falls into two main geographical areas, the
the use of night ventilation and evaporative cooling.
northern region and the much larger Saharan or southern
region. The northern region is made up of three parallel
geographical zones running east to west, with distinctive Vernacular Architecture; an Adaptation to the
climatic conditions and specific climatic design Contextual Environment
requirements (Figure 2). Each region developed a characteristic vernacular
architecture in harmony with the climate, geography,
topography and local building materials.
The northern part of the country, with a long colonial
influence, and a large industrial and urban expansion after
independence, has little authentic vernacular remaining.
The Casbah in Algiers, although not well preserved, is
certainly the most representative of what is remaining. It
is a good example of adaptation to site, and the prevailing
warm and humid climate. The urban fabric and the houses
naturally follow the topography, hence the slope of the
hills so as to take full advantage of the sea breezes
(Bensalem, 1997).
The villages on the cold mountains of the Aures are
clustered in a way that minimises heat losses and their
south orientations maximise sun exposure. Loggias are
Figure 2: The climatic regions in Algeria: (A): Temperate orientated south and shaded.
humid climate; (B). Semi-arid cold climate; (C). Semi-
arid hot climate; (D). Hot and arid climate of the desert.
The Tell region (A) is a narrow lowland strip,
interspersed with mountains, along the country’s
Mediterranean coastline. It is characterised by a temperate
climate with mild winters and summers. The high
humidity, however is the main source of discomfort in
both seasons. Givoni and Mahoney’s recommendations
for this climate, emphasise the use of cross ventilation
with protection in summer.
The Atlas Mountains (B) with an abundant fertile
soil, have a Mediterranean climate with longer cold
winters and occasional snowfall. Summers are
comfortable and less humid. The emphasis for comfort
should here be put on the winter period, with a prevailing
south orientation, provision for adequate sunshine
exposure and a well-insulated envelope.
Further South, the highlands referred to as High
Plateaux (C) maybe looked upon as two sub-climatic
zones, the northern and southern slopes of the mountains.
The northern semi-arid plateaux, sparsely populated,
Figure 3: View of a mountainous village.
containing a number of shallow salt lakes and supporting
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3. Bioclimatic potentialities of contemporary housing estates
Figure 5: View of Ghardaia’s setting, with compact urban fabric.
Figure 4. Village on the highlands The towns are all terraced; streets descend in circles
from the high point following the contours of the land. On
Under the extreme heat of the Sahara, well illustrated all but the south facing slopes, houses are open at the top.
by the M’zab valley towns and the “ksours”, the site was A central courtyard diminishes in area through two or
the first climatic response to the harshness of the climate three stories to a small skylight. On the southern side, the
and the sparse arable land. Most of the human settlements rooms, which usually surround the terrace on all four
there are set on the rocky part of the hills, saving the sides, are left open to the south.
fertile land.
Actually, the basics of dealing with the extremes of
summer conditions are similar from Morocco to India,
where most of the hot and arid climate zones are found.
Houses have developed simple but very efficient
strategies to cope with the climate. However, some
architectural variations exist. In the M’zab valley, social
and architectural differences are unique, due in part to the
puritanist conduct of the local Islamic indigenous
population, the ibadites, who erected five new towns one
thousand years ago. Ghardaia, the largest, located at 32-
north latitude is in one of the harshest climate. Summer
temperature often reach 45°C. The diurnal range is also
very large, while humidity is very low. Sandstorms are
frequent and it rarely rains.
The clear planning of these towns with fortified outer
walls, the dominant central mosque and the carefully
designed courtyard house make these communities one of
the most fascinating in Algeria.
Each town has a permanent winter town and a summer
town located in the nearby oasis. The winter town is the
main residence for mo st of the year. The summer town is
used at the hottest time of the year when the population Figure 6: Compact fabric, narrow streets, terrace roofs and two
levels courtyards in Ghardaia.
migrates to an environment that is cooler and shaded by
date palms.
The courtyard house in the M’zab is an overlaying of
The overall structure of the main town is compressed
two courtyards, as the usual house is three stories high.
and condensed. Houses are often part of one another
The ground floor is organised around the central physical
where walls are shared and boundaries are not easily
element of the house and receives light and air from a
recognisable. The resulting network of streets is narrow,
small opening in the roof called the chebeq (net). The first
enclosed and sometimes entirely covered, easing
floor is more open and used mostly in winter times. The
movements between neighbourhoods.
second floor is the terrace, which is well protected by a
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4. Kheira Tabet Aoul
high parapet and serves as a sleeping area on hot summer result is the standardisation of housing schemes, materials
days. There is seasonal nomadism between the two floors and construction technologies as well as the reproduction
as well as a daily one. The inhabitants move around the of typical plans indefinitely in all parts of the country
house to take full advantage of the optimum living with little variation or adaptation to the context.
conditions. The most common materials are reinforced concrete,
The typical feature in a mozabite dwelling is the prefabricated concrete panels, metal and glass. In these
“chebeq” (net), a more or less square hole in the ceiling buildings, high-energy consuming equipment for heating
which makes up for almost the total absence of windows. and cooling are necessary to achieve thermal comfort in
An iron grill protects it, and depending on the season and the hot regions.
the time of day, may be partially or totally obstructed.
The chebeq acts as an air conditioning device too as well
as a source of light.
It is worth noting that adaptation to local environment,
availability of materials and microclimate has resulted in
architectural variation or adaptation. For example, El
Oued with less palm timber available and frequent
sandstorms, has its entire town made on one-story
domed and vaulted houses built around courtyards to
prevent accumulating sand.
Figure 8: Typical social housing estates built throughout Algeria
The second category, which accounts for more than
40% of the actual housing production, is in the form of
individual housing estates. Here, the state provides plots
of land and one or two individual houses’ plans are
proposed. As the owner is the main actor in the
construction process, different materials are used. There
are also many deviations from the original type plan
imposed, as building regulations are rather limited and are
not strictly complied with. If building regulations exist at
the urban level and in relation to structures and
earthquakes, the national building is rather silent on such
matters as thermal performance or energy efficiency.
Recently, there has been an attempt to develop it at the
Maghrebin level (Algeria, Morocco and Tunisia) with an
EEC special fund. In this context, climatic data for the
three countries was gathered, a climatic classification was
carried out, actual and future energy consumption was
Figure 7: The domed and vaulted roofs in El Oued (Southern estimated, regional architecture was identified and details
Algeria) for typical building, materials and techniques were drawn.
These traditional settlements are a harmonious The next step should include parametric studies on
combination of social, geographical and climatic models as well as building an experimental 50 housing
adaptation in a given period of time. The lessons to be units in each country. It is however unfortunate to see that
learned from vernacular architecture are invaluable in for various reasons the programme is actually at a
terms of gaining understanding of the millennium standstill.
experiences embodied in design solutions adapted to the
local environment. However, it should be stressed that The Experimental
living conditions, contemporary needs and availability of
new materials have changed, thus care must be taken in Investigation
interpreting the traditional lessons. There are numerous studies about the bioclimatic
performance of vernacular architecture in the south of
Contemporary Era Algeria. Comparatively, little is known about the thermal
The contemporary housing production might be divided behaviour of the contemporary populace architectural
into two major categories. The apartment blocks are the production. Especially, that there is a widespread belief
state response to ever-increasing housing demands. A that all-present buildings under the hot climate are
deficit of 1.5 million units is estimated and it has never thermally inefficient. This is probably the case for the
been possible to achieve the target of 100 000 dwellings a standardised metal and concrete apartment blocks. It is
year. The bulk of the construction activities in the formal right that one may be tempted to generalise this to all
sector are undertaken by state-owned organisations. The types of constructions, as the new forms of buildings are
far from traditional designs.
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5. Bioclimatic potentialities of contemporary housing estates
In this context, the objective of a research initiated at and Mahoney’s recommendations for building design
Biskra university aimed first to evaluate the bioclimatic under such climatic conditions.
potentialities of the self-built houses. Then, investigate
the possibilities of improving their performance by minor Design Tools
passive design means. The hypothesis behind this lays in There are a number of methods to evaluate the thermal
the fact that if improvements can be made without a behaviour of a building. In site measurements are a
complete disruption of the construction process then they possibility but they are time consuming, expensive to run
may be readily incorporated. New designs like trombe and require adequate equipment. The other alternative is
walls, solariums, chimneys for ventilation may not be to simulate the real environment. Although, often in this
readily integrated in the construction process for various case some assumptions are made, they are powerful tools
reasons; inadequate to the context, new, unknown, and rapid to run.
expensive etc. There has been an attempt to introduce
solar ventilative chimneys by El Minaoui architects in the Traditional Versus Actual Climatic Design Tools
region of Biskra, but people’s unfamiliarity with the A number of traditional design tools exist, to assist at the
design blocked them. They argued that they infiltrated early stages of climatic integrated design, such as comfort
sand from wind and danger from scorpions. diagrams, solar charts, heat gain or loss calculations etc.
Hence a survey was carried out of over 100 individual They provide useful guidelines, based on rules of thumb,
houses in Biskra. This included the occupation of the plot on optimum site orientation, type of building components
of land, orientation, plans, façades, openings, wall properties, sun shading devices and openings as well as
colours, the details of the construction materials as well as indicate the potential requirements for ventilation, heating
administrating a questionnaire to the inhabitants to or cooling. However, they do lack precise quantitative
explore the way the spaces are used. assessments.
A typological classification was then carried out, first In order to evaluate and compare the thermal impact of
in terms of plot occupancy. Three main types emerged, various building parameters, there is a need for rapid
one that fully occupied the land, one that left a garden in evaluations of the building thermal behaviour. Today’s
front and those that left a band in the front and the rear of computer simulation tools present the advantage of rapid,
the house. flexible assessments. They allow to integrate most of the
The next step was to verify the thermal behaviour of elements involved in the building heat exchange.
the most representative types of houses. If these are to be On the other hand, they do require precise data, which
found thermally uncomfortable then the next stage aims may only be available at the latest design stages as well as
to test possible improvements gained through first the requiring a lengthy input process. Further, the non-
correct application of passive climatic design principles in integration of these assessments on Cad tools so far,
accordance with the user habits, preferences and ways of hinder their extensive use by designers.
construction (Sriti & Tabet Aoul, 1999).
DEROB-LTH (Dynamic Energy Response of
The Context; the City of Biskra Buildings)
Biskra, at the foot of the Aures Mountains is a DEROB-LTH, a powerful program for assessment of the
commercial centre for the nomads of the surrounding thermal behaviour in multizone buildings, was used in
region. It is located in the northern part of the desert at this investigation. It was first developed at the Numerical
34.8o North latitude, 5.73 longitude East and at the altitude Simulation Laboratory, University of Texas, Austin,
of 87m. USA. This latest version has been successively updated
It falls under the third climatic zone, the hot and dry and developed at the Department of Building Science at
climate. Thus, in winter it experiences mild days (average Lund Institute of Technology, Sweden. (Kvist Hasse,
16 to 22o C) but cold night temperatures (average 7-9o C). 1999).
The diurnal range is often greater than 10o C. Summer on The program consists of 8 modules. Six of the
the other hand is very hot, the temperature can easily modules are used to calculate values for temperatures,
reach 40o C, and the diurnal range for the hottest month heating and cooling loads. It can take account of 8
reaches 13 o C. Humidity varies between 40 to 70% in volumes and simulate buildings of arbitrary geometries.
winter but may drop to 15% during the hottest part of the
summer. Rain is rare and generally comes in the form of Base Case Model Used in DEROB
storms. The dominant wind direction is from Northwest to The base case model tested is the most recurrent type of
south east with 6 to 12m/s velocity (Atlas climatologique individual houses surveyed in terms of land occupation,
national, 1998; Capderou, 1985). morphology and architectural details. It consists of and L-
According to Givoni’s bioclimatic diagram, Biskra’s shaped building occupying over half of the rectangular
climatic data fall beyond the comfort zone for winter and plot of land with partial front garden and a backyard.
summer. High inertia of the envelope, provision of night It is 15m wide along the main façade, divided into 5m
ventilation and evaporative cooling should improve structural spans, and 10m along the contiguous walls with
summer conditions. The winter season would require bordering houses. Except for one span that goes to 15m
heating and that is despite the provision of internal gains. and encloses the partial front garden. The north, south
Appendices A and B present respectively the climatic orientation was considered for the base case, although the
data of Biskra along with its corresponding comfort chart survey highlighted random orientations according to the
1–5

6. Kheira Tabet Aoul
site and the existing street constraints. The impact of an Parametric Study
optimum orientation i.e southnorth was tested. The initial objective being to test gradually the least
disruptive changes in the building so as to be realistically
possible to incorporate them in the construction process.
Four main categories were considered.
• First the effect of the variation of the orientation
from north to south was tested for both summer and
winter (2 cases).
• Then the impact of various external wall properties
was tested. It included a self bearing wall (300 mm)
made of a locally produced material; the sand lime
brick which has the advantage of replacing the
expensive concrete and steel structure and requires
no surface treatment (mortar or plaster). An infill
with this type of brick within the traditional structure
was also tested (150mm of sand lime bricks instead
Figure 9: View of the model as simulated in DEROB
of the hollow concrete blocks). The double hollow
Internal load was evaluated according to the variation brick (100 and 150mm bricks) partition wall with a
of occupancy of the house (6 persons in total) and the use 50mm air space is also a commonly used
of its appliances and summed up to 23Wh/m². construction practice and was also tested. The last
Four windows of 1.5m width and 1.2m of height were type though hardly used was tested to evaluate the
used. One was on the south façade and the three others on impact of a highly insulated wall. Here, an insulating
the north façade. The recessed window frame within the material (polystyrene 50mm) replaced the air space.
wall thickness was simulated as a shading device on all These options were also tested for the summer and
windows. Closed window shutters at night and between winter period (8 cases).
11 am and 17 pm in summer were also taken into • The third category tested the impact of modifying
consideration. some roof properties, mainly to accommodate the
The ventilation rate was differently set for winter and summer extreme heat. First, an insulated roof was
summer. It was assumed to be 1ach/hr in winter except considered with a 50mm cork block (conductivity
for one hour of the morning were it was set to 5ach/hr 0.043 and specific heat 0.42). Then, the colour was
corresponding to the common practice of opening changed from a dark sandy one , 60% absorptance to
windows during house cleaning. Summer night a white one (25%). The second case tested the
ventilation was assumed to be equivalent to 20ach/hr for impact of shading the terrace with a 2m high
part of the night (1am to 7am) and 1ach/hr for the rest of parapet. This has the advantage of improving visual
the day. privacy for a space commonly used for sleeping in
The building components and the materials commonly summer. The impact of these options was tested for
used on the base case are listed with their thermal the hottest and coldest months of the year (6 cases)
properties in table 1. • Finally, an increase of window size from 8% to 15%
Table1: Building elements of the base case with their of glazing to wall ratio was tested for both seasons (2
corresponding material characteristics cases).
Thickness Conductivity Specific heat Density
Results and Discussion
(mm) (W/mK) (Wh/kgK) kg/m3 Since the initial objective is to assess the thermal
behaviour through the passive climatic features of the
existing houses, the results are presented in terms of
External wall
operative temperatures. This is the most relevant
Cement 15 0.93 0.29 1800
mortar parameter for thermal comfort.
Hollow concrete 150 1.1 0.3 1300
Block The Thermal Behaviour of the Base Case
Cement 15 0.93 0.29 1800
mortar In the original house modelled (base Case), the operative
Roof temperatures in winter are constantly below comfort
Cement 70 0.93 0.29 1800 level. They range from 11.7°C to 13.6°C, while the
Ribbed slab 200 1.15 0.3 2100 comfort zone, according to Mahoney’s tables is at least
Plaster 15 0.35 0.26 800
between 17 and 23°C at night. During morning in
summer, the temperatures are within the upper limit of the
Floor
comfort zone, but they do go beyond the comfort zone,
Earth 500 1.4 0.22 1300
particularly at night. The upper nights limit for comfort
Concrete 150 1.7 0.24 2300
being 25°C, while temperatures rise to 35°C.
Tiles 15 0.8 0.24 800
Window 40
U value=
5.0 W/m2K)
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7. Bioclimatic potentialities of contemporary housing estates
Impact of Orientation 14 18
16
17
13
15 14
Temperatures
Temperatures
13
12 12
11
9 10
7
11
8
5
1 3 5 7 9 11 13 15 17 19 21 23
10 6
Hours of the Day
1 3 5 7 9 11 13 15 17 19 21 23
South Orientation Winter North Orientation Winter Hours of the Day
Outdoor Temperature Winter Hollow Concrete Block Brick silico calcair 150mm
Brick silico calcair 300mm External wall air space
External Wall polystyrene Outdoor Temperature
Figure 10: Impact of north / south orientation in winter.
Figure 12: Impact of various types of external walls in winter.
There is little heat gain from changing orientation from
north to south in both seasons. 0.4°C is gained in winter 39 39
during midday and respectively 0.6°C in summer. 37 37
However, it should be noted that the limited glazing to
Temperatures
35 35
wall ratio (8% and 2.5% in each façade) explains this
limited influence. An increase in window size is certainly 33 33
required before any noticeable difference might be 31 31
pereceived.
29 29
Impact of Window Size 27 27
25 25
17 1 3 5 7 9 11 13 15 17 19 21 23
15 Hours of the Day
13 Hollow Concrete Block Brick silico calcair 150mm
Temperatures
11 Brick silico calcair 300mm External wall air space
External Wall polystyrene Outdoor Temperature
9
7
5 Figure 13: Impact of various types of external walls in summer
1 3 5 7 9 11 13 15 17 19 21 23
Hours of the Day
Impact of Roof Properties
South Orientation [8%] South Orientation [15%] The most interesting result lies on the impact of roof
Outdoor Temperature winter colour on the operative temperature during summer. It
decreases the operative temperature up to 1.8°C, which is
Figure 11: Impact of increased window size, south a substantial result due to the simple addition of white
orientation (winter) colour to the roof. Comparatively, the roof insulation and
the high parapets are less significant. The combination of
An increase of glazing from 8% to 15% ratio to the three parameters should be an interesting case and
window wall was tested for the south orientation only, would be taken for optimising the initial model.
where heat can be gained, for both summer and winter.
Up to 1.1°C is gained in winter when it is most needed,
while only 0.6°C is gained in summer. This is the result of 39
the high sunrays in summer as well as the effect of
37
closing the external shutters for most of the day. This 35
35
result is a positive passive design feature and further test
Temperatures
should be carried out to investigate the optimum glazing 33
to wall ratio for optimising winter heat gain. 30
31
29
Impact of wall properties 27
The test on the various types of walls shows little 25 25
variation for both summer and winter. However, the more 1 3 5 7 9 11 13 15 17 19 21 23
stable thermal behaviour of the sand lime brick wall Hours of the Day
(300mm) has to be noted, as by its thickness it increases
Roof non- insulated Roof insulated roof colour
wall’s inertia. Further, if the comparison is done on a cost
roof parapet Outdoor Temperature
basis too, then the latter would be more advantageous,
being a bearing wall. This reduces greatly the high cost of
Figure 14: Impact of various roof types in summer
the traditional structure of concrete beam and columns.
1–7

8. Kheira Tabet Aoul
Optimum Case etc... These aspects however fall beyond the scope of this
Finally, a test was run with the optimum parameters for study and should be the target of future work.
each category considered. The main glazed façade was
orientated south. The external walls were made of 300mm Conclusions
sand lime bricks. An insulated roof with a white colour The most important benefit gained through this
and 2m high parapets was adopted. 15% glazing to wall investigation lies beyond the specific results obtained. A
ratio was considered for the opening. better understanding of climatic design generates the
impetus to integrate it into any future design.
17 Solar energy applications to architecture hold a lot of
promise for developing countries because in addition to
Temperatures
14
being environmentally expedient they are also
technologically less sophisticated and may lead to
11
substantial energy savings in the building industry. It
8
must be stressed that when the recommendations are
achieved to a reasonable extent, the greatest impetus to
5 the development of passive solar architecture would be
1 3 5 7 9 11 13 15 17 19 21 23 25
outright statutory support in the form of regulation and
Hours of the Day incentives as well as the proper training of building
professionals,
Out Temp BaseCase Optimum Finally, it is hoped that this study is a modest
contribution towards a better understanding of thermal
comfort and housing design by passive means.
Figure 15: Effect of optimising all parameters in winter References
Atlas Climatologique National. (1998) Office National de
Meteorologie, ONM, Algiers, ONM Biskra.
40
Bensalem, R., (1995), “climate responsive architecture”,
35 Arhitecture, energy and environment, Tools for
climatic Design, Lund Centre for Habitat Studies,
Temperatures
30
Lund University. Sweden.
25
Capderou, M., (1985) Atlas solaire de l’Algerie Tome
2,OPU, Algiers, Algeria.
20
1 3 5 7 9 11 13 15 17 19 21 23 25
Givoni , B., (1998) , Climate considerations in Building
Hours of the Day
and urban design, Van Nostrand reinhold, new
Outdoor Temperature Base Case Summer optimum Summer york.
Figure 16: Effect of optimising all parameters in summer Guellouz. K., (1992), Seminar: Reglementation thermique
des batiments dans les pays du Maghreb, Tunis,
Although, temperatures remained outside the comfort p.5.
zone for winter, it should be stressed that a 2.5°C increase
compared to the base case is a positive result, taking into Kvist Hasse (1999) DEROB-LTH for windows. User
consideration the minor changes tested. Similarly, in Manual. Department of Building Science. Lund
summer the reduction of up to 1.7°C during the evening is Institute of Technology, Lund University. Report
a positive trend. Summer temperatures are within the limit TABK-99/7019.
of the comfort zone during the day but not during the
night, when stored heat is transmitted indoors. However, Sriti, L ; Tabet Aoul, K., (1999), Etude et optimisation de
due to the traditional lifestyle of the inhabitants of Biskra, la performance thermique de l’habitation
where people sleep outdoors in summer, this might be a individuelle contemporaine, cas d’etude Biskra,
minor effect. Seminar on renewable energy , 11-12 November,
As a mean of summing up, one might say that given Algiers, Algeria
the conflicting requirements for equal consideration of
both seasons (cold winters, hot summers), the exercise of Tabet Aoul, K., (1996), Housing design, energy
optimisation will be limited to a certain extent. Favouring, conservation and building regulation: the case of
for example summer protection hinders winter benefits. Algeria, the 4th European Conference on
Further, there is probably a limit to the impact of Architecture, Berlin, Germany, 26-29March; pp.
passive design means on thermal comfort, if they are
solely related to the sole features of the building. Extra
benefits will be gained through the sound site layout,
street height to width ratio, including vegetation, water
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9. Bioclimatic potentialities of contemporary housing estates
Appendix B
Location Biskra
Longitude 5.73 °
Latitude 34.8 °
Altitude 87 m
Air temperature °C Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec High AMT
Monthly mean max. 16.8 18.6 21.9 25.5 30 36.3 39.3 38.5 33.6 27.1 20.8 17.5 39.3 23.15
Monthly mean min. 7 8.9 11 14.2 18.5 23.6 26.8 26.4 22.7 16.9 11.4 8 7 32.3
Monthly mean range 9.8 9.7 10.9 11.3 11.5 12.7 12.5 12.1 10.9 10.2 9.4 9.5 Low AMR
Relative humidity % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Monthly mean max am 69.9 70.6 60.3 57.3 53.2 45.9 39.4 45.3 57.4 64.3 71.5 72.2 1 <30%
Monthly mean min pm 35.3 32.7 25.2 22.7 20.2 16.5 14.8 18 25.9 31.6 37.2 38.9 2 30–50%
Average 52.6 51.65 42.75 40 36.7 31.2 27.1 31.65 41.65 47.95 54.35 55.55 3 50–70%
Humidity group 3 3 2 2 2 2 1 2 2 2 3 3 4 > 70%
Rain and wind Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
Rainfall mm 13.3 12.9 7 12.7 13.5 5.1 3.5 8.5 10.5 12.2 21.4 3.5 124.1
Wind, prevailing NW NW NW NW NW N, NE, E, SE,
Wind, secondary N N NW S, SW, W, NW
Diagnosis °C Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec AMT
Monthly mean max 16.8 18.6 21.9 25.5 30 36.3 39.3 38.5 33.6 27.1 20.8 17.5 23.15
Day comfort, upper 29 29 31 31 31 31 34 31 31 31 29 29
Day comfort, lower 23 23 25 25 25 25 26 25 25 25 23 23
Thermal stress, day C C C O O H H H H O C C
Monthly mean min 7 8.9 11 14.2 18.5 23.6 26.8 26.4 22.7 16.9 11.4 8 H=Hot
Night comfort, upper 23 23 24 24 24 24 25 24 24 24 23 23 O=Comfort
Night comfort, lower 17 17 17 17 17 17 17 17 17 17 17 17 C=Cold
Thermal stress, night C C C C O O H H C O C C
AMT >20°C AMT 15–20°C AMT <15°C
Comfort limits Day Night Day Night Day Night
Humidity group Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper
1 26 34 17 25 23 32 14 23 21 30 12 21
2 25 31 17 24 22 30 14 22 20 27 12 20
3 23 29 17 23 21 28 14 21 19 26 12 19
4 22 27 17 21 20 25 14 20 18 24 12 18
Meaning Indi- Thermal stress Rainfall Humidity group Monthly mean range
cator Day Night
Air movement essential H1 H 4
H 2–3 <10°C
Air movement desirable H2 O 4
Rain protection necessary H3 >200mm
Thermal capacity necessary A1 123 >10°C
Outdoor sleeping desirable A2 H 12
H O 12 >10°C
Protection from cold A3 C
Indicators Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
H1
H2
H3
A1 1 1 1 1 1 1 1 1 8
A2 1 1 1 3
A3 1 1 1 1 1 5
1–9

10. Kheira Tabet Aoul
Indicator totals from data sheet
H1 H2 H3 A1 A2 A3
8 3 5
Low High Low High Low High Low High Low High Low High Layout
0 10
1 Orientation north and south (long axis east–west)
5 12
11 12
0 4 Compact courtyard planning
Spacing
11 12 Open spacing for breeze penetration
2 10 As above, but protection from hot and cold wind
0 1 1 Compact layout of estates
Air movement
3 12 Rooms single banked, permanent provision for air
0 5 movement
1 2
6 12 Rooms double banked, temporary provision for air
2 12 movement
0 0
0 1 1 No air movement requirement
Openings
0 1 0 0 Large openings, 40–80%
11 12 0 1 Very small openings, 10–20%
Any other conditions 1 Medium openings, 20–40%
Walls
0 2 Light walls, short time-lag
3 12 1 Heavy external and internal walls
Roofs
0 5 Light, insulatted roofs
6 12 1 Heavy roofs, over 8h time-lag
Outdoor sleeping
2 12 1 Space for outdoor sleeping required
Rain protection
3 12 Protection from heavy rain necessary
Size of opening
0 0 Large openings, 40–80%
0 1
1 12
Medium openings, 25–40%
2 5
6 10 1 Small openings, 15–25%
0 3 Very small openings, 10–20%
11 12
4 12 Medium openings, 25–40%
Position of openings
3 12 In north and south walls at body height on windward
0 5 side
1 2
6 12
1 As above, openings also in internal walls
0 0 2 12
Protection of openings
0 2 1 Exclude direct sunlight
2 12 Provide protection from rain
Walls and floors
0 2 Light, low thermal capacity
3 12 1 Heavy, over 8h time-lag
Roofs
0 2 Light, reflective surface, cavity
10 12
3 12
Light, well insulated
0 5
0 9
6 12 1 Heavy, over 8h time-lag
External features
1 12 1 Space for outdoor sleeping
1 12 Adequate rainwater drainage
1–10