An
Assignment on Arc 810
(APPLIED CLIMATOLOGY)
GUIDELINES FOR DESIGN WITH CLIMATE IN
THE SAVANNAH ZONE OF NIGERIA
(Implications for prototype mass housing)
By
ADEGBENRO OLALEKAN O.
(Arc/04/3162)
Submitted to
THE DEPARTMENT OF ARCHITECTURE,
FEDERAL UNIVERSITY OF TECHNOLOGY AKURE.
COURSE LECTURER
Prof. Ogunsote
AUGUST, 2011
1
TABLE OF CONTENTS
ABSTRACT
1.0
INTRODUCTION ………………………………………………………………
2.0
STUDY AREA
3.0
CLIMATE IN THE SAVANNAH ZONE
4.0
DESIGN GUIDELINES IN THE SAVANNAH ZONE
5.0
……………………………………………………………
……………………………………..
…….……………….
……………………………..
4.1
Building Configuration and Orientation
4.2
Openings
4.3
Building Materials
…………………………………………………….
4.4
Outdoor Spaces
……………………………………………………..
…………………………………………………………….
RECOMMENDATIONS AND CONCLUSION
REFERENCES
2
……………………………..
Abstract
The habitant bill of rights, defined the qualitative issues connected with design of houses and
their groupings into new communities as a supplement to other codes and regulations which
have attempted to define qualitative issues relating to the building industry. In the northern part
of Nigeria, which houses the savannah zone have evidences of low quality in design and
planning of houses, relative to environmental influences, like weather and regular seasons. The
zone covers a large portion of the country and consists of towns like Sokoto, Yelwa, Kano,
Gusau, Maiduguri, Yola, Ibi, Potiskum, Minna, Bida, Abuja, Zaria, etc. It has been observed that
the weather condition in this part of the country is prone to dry and hot climate from early
February to June. This period gives residents in the area a perpetual experience of living amid
extreme dryness and exhaustive heat as from midday to midnight throughout the period. It needs
therefore the refreshing coolness of people’s habitat and surroundings. From the end of June to
September, the weather is fairly good with intermittent rains and showers sometimes
accompanied by strong winds and storms. In early October, when the heat varies, powdered dust
particles are brought from Sahara by the harmattan winds. The harmattan period extends as far
as January when an ambient temperature within the interior could go as low as between 8 and
10oc thereby requiring heat. From the observations, it’s clear that the inhabitants of this area
are faced with problems of designing and constructing suitable houses that will cope with these
varying climatic conditions, such that the minimum hardship is suffered during both the hot and
harmattan periods while employing minimal mechanical cooling and heating devices
respectively. The aim of this study is to provide a design guideline putting the climate of the
savannah zone into consideration which will provide adequate comfort for the inhabitants of
such area and can be adopted as prototype for mass housing scheme in the area which involves
the use of different kinds of building materials, building orientation, spacing, types and sizes of
openings, etc.
Keywords: Climate, Savannah Zone, Thermal Comfort, Discomfort, Openings.
3
1.0
INTRODUCTION
The primary function of all buildings is to adapt to the prevailing climate and provide an internal
and external environment that is comfortable and conducive to the occupants. However, in this
era of climate change and global warming, providing comfort for the occupants of a building is
quite challenging and very fundamental. This is as a result of growing ranges of challenges now
facing designers to provide buildings that will be fit and comfortable (Akande, 2010).
The need to design with climate has always been a major consideration in architecture. Vitruvius,
in his Ten Books on Architecture drew attention to the importance of climate in architecture and
town planning. Climate in a narrow sense is usually defined as the “average weather”, or more
rigorously, as the statistical description in terms of the mean and variability of relevant quantities
over a period ranging from months to thousands or millions of years (Wikipedia). The classical
period is 30 years, as defined by the world metrological Organisation (WMO). These quantities
are most often surface variables such as temperature, precipitation, and wind.
Architectural design is defined by boundary because of the variation of climatic zones. There are
six zones that have been defined for Nigeria: the coastal Zone, the forest zone, the transitional
zone, the savanna zone, the highland zone and the semi-desert zone, but for the purpose of this
study, we are going to base only on the savannah zone which covers majorly the northern part of
the country (Yelwa, Sokoto, Gusau, Kano, Maiduguri, Yola, Ibi, Potiskum, Minna, Bida, Abuja,
Zaria). There are design guide lines that are common to all these zones, if all these are observed,
then all the architectural design will adapt to their environment.
Architectural design should enable the occupant of the building to achieve thermal comfort.
Thermal comfort basically has to do with the temperature that the resident considers as
comfortable to stay in. Indoor thermal comfort is achieved when occupants are able to pursue
without any hindrance, activities for which the building is intended. Hence, it is essential for
occupants well being, productivity and efficiency.
This paper takes a look into the climatic condition of the savannah region of the country Nigeria
and sees how Architecture can be incorporated into the designing of buildings that will give the
inhabitants thermal comfort and on the long run could be used as a prototype for the designing of
subsequent buildings in the area.
4
2.0
STUDY AREA
The study area selected for the purpose of this paper is the savannah zone of the country, which
is majorly found in the northern part of Nigeria. The savannah zone is the only zone that has the
highest number of cities and towns it covers and is predominantly known for its hot-dry climate,
which the makes the weather harsh for the inhabitants of such area. some of the towns covered
by the savannah zone include; Sokoto, Yelwa, Kano, Gusau, Maiduguri, Yola, Ibi, Potiskum,
Minna, Bida, Abuja, Zaria, Bauchi and so on.
Map of Nigeria showing the towns in the savannah zone
5
3.0
CLIMATE IN THE SAVANNAH ZONE
It has been observed that the weather condition in this part of the country is prone to dry and hot
climate from early February to June. This period gives residents in the area a perpetual
experience of living amid extreme dryness and exhaustive heat as from midday to midnight
throughout the period. It needs therefore the refreshing coolness of people’s habitat and
surroundings. From the end of June to September, the weather is fairly good with intermittent
rains and showers sometimes accompanied by strong winds and storms. In early October, when
the heat varies, powdered dust particles are brought from Sahara by the harmattan winds. The
harmattan period extends as far as January when an ambient temperature within the interior
could go as low as between 8oc and 10oc thereby requiring heat.
Cold nights and hot days alternate for six to ten months of the year. This usually accelerated
during the harmattan period where the ambient temperature within the inside of the building
could go down as low as between 8oc and 10oc. In this case, thermal storage is needed in keeping
the interior cool in the day and providing warmth at night.
Climatic Variation in the Northern Climatic Zone (Savannah Area)
Zones
Northern
Seasons
Air
temperature
Day
Night
oC
oC
Humidity
%
Hot Dry (Nov/Dec to April/May)
32-43
15-27
20-55
Warm Humid (May/June to Sept)
27-32
24-27
55-95
Cool Dry (Sept/Oct to Nov)
18-27
4-15
20-55
Annual
Rainfall
(mm)
Wind
(km)
1-10
500-1300
1-10
Nigeria
Source: National Universities Commission (1977). Standard Guide for Universities
6
1-10
4.0
DESIGN GUIDELINES IN THE SAVANNAH ZONE
There are some design guidelines that can be put into use by the designer in achieving a thermal
comfort for the inhabitants of the Savannah zone. Buildings are designed and built to provide
shelter for man and protect man from harsh weather conditions and achieving the maximum
thermal comfort for the occupant. In the savannah zone, the kind of climate in existence should
be put into maximum consideration, because it determines the kind of design and materials to be
used and also the orientation of the structure as well.
The following classifications will help in carrying out a good design in this zone and can
therefore be adopted as a prototype for prospective building designs which might be in form of
mass housing.
4.1
Building configuration and Orientation
This refers to the method or way in which the building with its environment is going to be
catered for or arranged. It also refers to the configurations in the design and how the spaces are
to be arranged. It comprises of the orientation of the building in respect to the sun and also the
prevailing wind. In hot-dry climate regions, it is desirable to lower the rate of temperature rise of
the interior during day time in summer. To achieve this, the building should preferably be
compact. The surface area of its external envelope should be as small as possible, to minimize
the heat flow into the building. The ratio of the building envelope’s surface area to its volume or
ratio of floor area to its volume determines the relative exposure of the building to solar
radiation. The best layout is that of a patio or a courtyard surrounded by walls and thus partially
isolated from the full impact of the outdoor air. This configuration is very common in hot-dry
climate. The surface of the buildings must be protected from excessive solar gains from the sun,
by having an orientation placing their long axis east – west, that is, the longer sides of the
building should face the north and south direction. For the purpose of ventilation, there is the
need to have open spaces in the building area and such spaces must be protected against hot and
cold winds. The spaces allocated as rooms should be single banked, that is, there must be a direct
flow of air through the building from one side to the other without any wall barrier. This
therefore means that permanent provision should be made for constant air movement in and out
of the building.
7
Spacing of buildings with openings serving as courtyards
4.2
Openings
Openings refer to different open able areas in the building. They include the windows and also
the doors. For the purpose of this study, we are going to base it only on windows being the
openings in the building. Due to the climatic condition of the savannah zone, the kind of
openings that will be used will be quite different from the other zones with different climatic
analysis. The savannah zone being a hot and dry zone will require the use of composite windows
which are to occupy between 20% to 35% of the wall area. These openings should be able to
catch the breeze and improve body cooling. This will make the interior of the building
comfortable for the occupant. Permanently open ventilation vents should be introduced to allow
for permanent ventilation throughout the year. These openings must be protected against sun and
rain during hot sunny periods and heavy downpours. The use of sun-shading devices can help in
reducing the amount of sunlight entering into the interior and thereby help in maintaining normal
comfort in the building. Roof overhangs of adequate sizes and geometry can help in reducing the
driving force of rain from entering through the window into the building.
8
Shading of openings from sunlight and rain
4.3
Building materials
Building materials affect the kind of thermal comfort that the occupant of the building will
experience. Due to the kind of climate in the savannah zone, and the necessity to reduce the rate
of gain of heat energy into the building during the day, and the desire to keep the inside of the
building warm at night when the temperature drops, the use of heavy weight materials should be
used in the construction of such buildings. Such materials should be with high thermal capacity
and having a time lag of over 8 hours. The kind of materials that can be used for flooring,
roofing and walls should possess high thermal capacity or the ability to store heat and there by
delay or reduce the flow through the material into the inner part of the building. With the time
lag of over 8 hours, from when the sun is at its maximum brightness (2pm) to about 10 pm in the
night, is when the heat stored in the building will find its way into the interior of the building,
thereby keeping it warm and comfortable for the occupant.
Examples of such materials include stone masonry, well compacted mud, bricks, RCC slab
covered with insulation materials for roofing, timber or wood, etc.
9
Brick wall with good thermal storage
4.4
Outdoor Spaces
These spaces refer to outdoor openings which might be in form of courtyards and also verandahs
or balconies. These spaces should be well shaded from intense sunlight and heat, and also from
the driving force of rain. It is advisable and better to have the outdoor spaces incorporated into
the building which can sometimes serve as an outdoor sleeping area in times of intense heat at
night.
Open spaces have to be seen in conjunction with the built form. Together they can allow for free
air movement and increased heat loss or gain. Open spaces in any complex are inevitable. The
question is how should they be and how much should there be? After all, any built mass modifies
the microclimate. An open area, especially a large one allows more of the natural climate of the
place to prevail. Open spaces gain heat during the day. If the ground is hard and building
surfaces are dark in colour, then much of radiation is reflected and absorbed by the surrounding
buildings. If however, the ground is soft and green, then less heat is reflected.
In hot-dry climates, compact planning with little or no open spaces would minimize both heat
gain as well as heat loss. When the heat production of the buildings is low, compact planning
minimizes heat gain and is desirable. This is how traditional settlements often are.
Principle of the courtyard: Due to the incident solar radiation in the courtyard, the air in the
courtyard becomes warmer and rises up. To replace it, cool air from the ground level flows
10
through the openings of the room, thus producing the air flow. During the night, the process is
reversed. The cooled surface air of the roof sinks down to the court and this cooled air enter the
living spaces through the low level openings and leaves through higher level openings. This
system can work effectively in hot and dry climates, where day time ventilation is undesirable, as
it brings heat inside and at night the air temperature becomes cooler.
A courtyard with water fountain at the middle
The best way to keep the courtyard shaded and partially open to the sky
11
5.0
RECOMMENDATIONS AND CONCLUSION
Climate should be the most important factor considered by an architect when designing a
building. Architectural design is meant to solve the problem of shelter and shelter is meant to
protect from harsh weather, dangers (wild animals, thieves) and harsh climatic conditions.
Therefore, architectural design should be made in view of weather or climate. In the final
analysis, it realized that architects should study the climate of region (savannah) and design
should made to conform to the climate (i.e.) it should be habitable and comfort should be
achieved despite the climate.
Also, materials recommended for construction of architectural design in the Zone should be
adhered to and should be that which is favorable with the climate condition present where it is
suppose to be constructed.
Importation of architectural designs from overseas is not appropriate because of the variation in
the climatic conditions existing in both area, therefore appropriate consultation should be carried
out in the region to understand the kind of weather or climate that exist in that region before
architectural design is commenced.
Following conclusions are drawn from the study presented herein with respect to Architectural
design in hot-dry climate of the savannah zone:
i.
To minimize energy demand and provide better degree of natural conditioning, it is
essential to give climatic considerations for designing of residential buildings.
ii.
For a building to function in co-ordination with the environment there should be a
relation between the interior and exterior environment, orientation, building form,
materials etc.
iii.
Orientation of the overall built form should be in co-ordination with the orientation of the
sun and prevailing wind direction.
iv.
Rectangular form of the building should be elongated along east-west direction, i.e., the
orientation of the building should be north-south.
12
v.
When buffer spaces are provided between exterior and interior spaces, heat from outside
dissipates before entering interiors. Non-habitable rooms such as toilets, stores and
galleries can be provided as heat barriers in the worst orientations on the outer periphery
of the building.
vi.
Provision of a central courtyard is preferable which helps in achieving shaded spaces,
natural light in most of the places and better circulation of air without providing many
openings on the exteriors surfaces. However, provision of courtyard is effective only if it
has a plan area and volume relationship proportional to built-up area and its volume.
vii.
Thick walls create thermal time-lag, thus creating comfortable conditions.
viii.
As the position of a window goes higher, light penetration increases with lesser heat gain.
13
REFERENCES
Agarwal, K.N., Thermal data of building fabric and its application in building design, Building
Digest, No. 52, June 1967, CBRI, Roorkee, India.
Akande, K. O.,Indoor Thermal Comfort for Residential Buildings in Hot-Dry Climate of Nigeria,
proceedings of conference: Adapting to Change: New thinking on Comfort, Cumberland Lodge,
Windsor, UK, 9-11 April 2010, London.
Anderson, B., Solar Energy Fundamentals in Building Design–Total Environment Action,
McGraw-Hill Book Co., 1977.
Arorin, J. E. (1953). Architecture and Climate. Reinhold Publishing Corp., New York.
Evans, M. (1980). Housing, Climate and Comfort. The Architectural Press, London.
Krishan, A., Climate Responsive Architecture–A Design Handbook for Energy Efficient
Buildings. Tata McGraw-Hill Pub. Co. Ltd., New Delhi, 2000.
Krishan, A. and Agnihotri, M.R., Bio-climatic architecture – a fundamental approach to design,
Architecture+Design, Vol. 9, No. 3, May-June, 1992.
Nicol, J.F. and Humphreys, M.A. (2004), Adaptive Thermal Comfort and Sustainable Thermal
Standards for Buildings. In the Proceedings of Moving Thermal Comfort Standard pp 150-165.
Ogunsote, O. O. (1990a).Architectural Design with Nigerian climatic condition in view: A
Systems Approach.
Rao, K.R. and Prakash C., Thermal performance rating and classification of walls in hot climate.
Building Digest, No. 101, October 1972, CBRI, Roorkee, India.
Straaten, V.J.F., Thermal Performance of Buildings. Elsevier Pub. Co., Amsterdam, 1967.
14