Guidelines for Design with Climate in the Coastal Zone of Nigeria: Implications for prototype mass housing.

By

Alelumhe Jeremiah Irhenaye

Arc/05/5593

Department of ArchitectureFederal University of Technology, Akure

In Partial Fulfilment of the course

Applied Climatology (Arc 810)

Course Lecturer: Prof.Ogunsote.O.O

August, 2011

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TABLE OF CONTENTS

1.0 Introduction

2.0 Characteristics Of The Coastal Zone

2.1 The Use Of Surfer Software In Analysing Rainfall Pattern for the Coastal Zone

3.0 Case Study-Proto Type Mass Housing At Unilag

3.1 Background of Case Study

3.2 Implications of design guidelines for Prototype Mass Housing

4.0 Conclusion

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1.0 INTRODUCTION

The coastal zone which is one among the six zones in Nigeria climatic zones is highly

characterised with high amount of rainfall since most of the states found here are located

along the coastal bank of the atlantic ocean and this have resulted to its high level of rainfall

and humidity.In achieving and establishing workable guidelines for the designs especially of

prototype mass housing in nature, a careful consideration should be taken to ensure a design

that will be able to combact the twin elements of high amount of rainfall and heated up hours.

This guidelines should span through the choice of materials to be used in the various

elements of the building,size of openings,orientation of buildings,position of openings and

lots more to be able to produce a design that is green in attribute,environmental friendly,and

promote human comfort.

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2.0 CHARACTERISTICS OF THE COASTAL ZONE

The coastal zones which includes cities such as Ikeja,Lagos,Ondo,Benin,Warri,Portharcourt

and Calabar is highly characterised with high humidity and hot discomfort for eleven or more

months in the year which makes the provision of permanent ventilation essential.The monthly

rainfall exceeds 200mm for three or more months in a year and the table below confirms that

for the mean range of temperatures of cities in the coastal zones for the span of 29 years

hence a high level of design shading away rainfall is necessary in this zones and there is a

high need to inculcate self drained systems that will channel this water appropriately or

recycles the water for household use.There is no need for thermal storage as high diurnal

temperature range of more than 10 degrees coupled with low humidity is not experienced for

more than one month in the year and the monthly maximum temperature never falls below

the comfort limit,thus no special precautions need be taken against cold discomfort.

Fig 1:Chart showing the linear trend of rainfall for the coastal zone having the higest range of rainfall

calab

aryel

wa

kaduna

birni-k

ebbi

akure

lokoja

maidugu

ri

potiskum

mokwa

onnesad

o

osogb

omubi jos

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

450.00

R² = 0.533905132080308

TIME SERIES WITH LINEAR TRENDS OVER THE STATIONS (1978-2007)

MAR

JUN

SEP

Linear (SEP)

RAIN

FALL

(mm

)

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Tale 1:Showing Data for mean range of rainfall for 28 states for the period of 1978-2007 Source:IITA,Ibadan,2010.

2.1 THE USE OF SURFER SOFTWARE IN ANALYSING RAINFALL PATTERN

Surfer is a grid based contour program.sufer transforms XYZ data to create contour maps,3D

surface maps,3D wire frame maps,shaded relief maps,rainbow colour “image” maps,post

maps,classed post maps,vectormaps,and base maps.It can calculate cross sections,areas,and

volumes.

In analyzing the rainfall pattern for the coastal zones,the surfer software was used to plot the

map of nigeria showing the various climatic zones with the coastal zones having the highest

amount of rainfall.

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Fig 2: showing the graphical interface of surfer programme

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Fig 3: Map showing mean range of rainfall for coastal zones having the highest range of rainfall

Source:researcher’s file ,2011.

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3.0 CASE STUDY-PROTO TYPE MASS HOUSING AT UNILAG

3.1 Background of Case Study

The various plates used in this write up was gotten from the mass housing quaters of the

University of Lagos Nigeria which is located in the coastal zone of Nigeria climate.The

prototpype mass housing which are sets of prototypes high rise A, B and C and prototypes of

3,and 4 storey buildings of different volumes and shapes built to house the university staffs of

different levels and categories are worthy of study to acertain and establish guidelines for

prototype mass housing designs for the coastal zones of nigeria.

3.2 Implications of design guidelines for Prototype Mass Housing

The guideline for designs in the coastal zones of nigeria has its implication on prototype mass

housing systems in the coastal zones of the country as many factors will be put in place in

ensuring a mass housing pattern that will enhance cross ventilation and maximize the cool

breeze that flows through the North-South Elevations of the buildings and effeciently utilize

the advantages of the coastal zones and try to minimize to the bearest minimun the

disadvantages.Harnessing these specialities in the zone will create a well habitable space that

will promte users functionality and human comfort.Having studied some of the mass housing

quarters in the University of Lagos,Nigeria to assess the implications of these design to thus

serve as a guidelines for prototype mass housing,the following obseravtions were made;

3.2.1 SITE PLANNING AND LAYOUT:The layout of the buildings were of north-south

with the longer axis facing east-west.This was so done so as to trap in the cool air that blows

from the north so that the occupants of the building could feel the cool breeze that blows at

evening times for body comfort.Also noticed was large spaces between buildings to allow

breeze penetration. This was so planned in a manner to allow the windward side to feel the

much impact of the cool air and aviod thesame prototype building blocking the air or causing

suction on other building.The house form also reduces exposure to solar radiation.

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Plate 1:showing unilag prototype mass housing of three storey arrange in row form to give a maximum flow of air and reduces solar radiation by placing the smaller side in the east and western elevation

Plate 2:showing proto type high rise ‘B’mass housing arranged in staggered form to maximum flow of air.

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N Wind direction flow N N N

suction

H1 H2 H3 H4

E W

S S S S

Fig 4a: showing the row arrangement pattern for maximum air flow

Direction of air flow

air flow airflow

Fig 4b showing: a staggered arrangement of the high rise buildings in a way to permit

air flow through the buildings.

Plate 2: showing a staggered positioning of the buildings.

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airflow

airflow

h

d=7xh

d

fig 5:showing the distance between each building that will permit adequate flow of air.

d=7xh d=7xh

Fig6:showing buildings arranged in a staggered form to permit maximum amount of

airflow around the building.

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3.2.2 OPENING:

Opening of fenestration on the northern and southern elevation were large enough to admit

large amount of air flow and provide enough room for cross ventilation.The western and

eastern walls for the above prototype has no fenestration at all.This shows that more of

radiation is not needed due to lack of need for thermal storage and the windows should be

large and situated preferably in north and south walls.Permanent ventilation should be

provided.Their position should encourage booding cooling.Sunshading devices must be

exclude the sun through out the year.Rain penetration through windows can also be solved

through horizontal shading device tinted at an angle.

3.2.3 STRUCTURE AND MATERIALS:

Walls and floors should ideally be light and of low thermal capacity.This requirement is

difficult to satisfy for floors but walls can be made of louvred shutters and light weight

materials of minimal storage capacities.Roofs should be light,with a relected surface and

cavity for ventilation.The reflective surface of roofs reduces solar heat gain by the roof.The

finishing of walls and roofs should be light to reflect sloar heat.These finishes should protect

against driving rain.

Plate 3:showing the use of brick facing as finishing materials in the non-opening walls

for thermal control.

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3.2.4 OUTDOOR SPACES:

Balconies were utilized much in the high rise mass housing buildings studied.This balconies

were provided to enhance a greater effeiency of trapping the cool breeze that flows at evening

time.Also overhangs and horizontal shading device were employed in the windows for

shading against the sun.The windows are recessed with the horizontal shading device

protuding out to completely keep the sun away from the northern and soythern

elevations.This is shown in the plate below.

Plate 4: showing out door spaces used in the balconies

3.2.5 SIZE OF OPENINGS:

The size of the openings should be large with 40-80% of this openings facing the North and

South walls.This was the case in the prototype mass housing studied in unilag.This is to allow

the gentle penetration of the south west trade wind in the windward direction so that the

occupants can feel the cool breeze in that blows in the evening time.The eastern and the

western walls should have about 20% of openings and the openings should preferably be of a

medium size to permit minimum amount of sunlight and should be shadded appropriately

with shading device to shade away the sunlight.

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Plate 5:The proto type mass housing above have this characteristics with the eastern

walls have smaller windows and the northern and southern walls having more of the

larger windows.

3.2.6 PROTECTION OF OPENINGS:

protection from rain and direct sunlight can be achieved in a way through the use of shading

device and mostly through the use of trees planted at appropriate distances say 30m from the

building. If a tree is planted say some distances from the window of the massed buildings, it

will hinder an even spread of air through the rooms since the speed of the incoming air will

be retarded down by parts of the tree or even more still those molecules of air that escape

through the pores between the branches and the tree will of course not be at even speed when

entering the house and this will give an uneven air movement throughout the room.

The speed of air above the tree is likely to be of a greater velocity followed by the speed of

air beneath it and the air that flows in a direction that is directly proportional to the trees parts

is more likely to be retarded. This principle is likely employed to cool than the wind velocity

of stormy rains by planting trees of growth height parallel to that of the windows so as to

serve as wind breaker and retarder hence creating an atmosphere of lesser wind effects.

Similarly, the amalgamation of trees and hedges can be used to direct air flow and wind since

the soft landscape will allow the escape of air molecules while the hard landscaping elements

may reflect air flow and reverse its direction.

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Another elements note of mention here is the window type. Normally Louvered windows is

best for mass housing since it gives room for about to 95%-98% air flow in and out while

about 2% is reflected by the edges of the louvers. Hence as guideline for designs of mass

housing settlement that requires the best in terms of cross ventilation; louvered window will

perform best and can also act as a shading device when tinted at an angle though not to a

greater degree of performance in terms of shading. Also louver can be used to maximize and

minimize appropriate the level of air flow through the openings by tinting the angle of

opening.

More also openings can be protected by using the appropriate shading device. This can both

act as shading against the sun and act as a protective cover against the driving wind. Also the

nature and position of sun shading is paramount consideration when determining the choice

of sun shading device. Recessing window inward can create greater effects in terms of

shading the openings away from the sun and also from the driving rain.

Plate 6:showing trees used as shading device against the sun and to also reduce the effects of driving rain.

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airflow

Fig 7: showing the air flow and speed of rainfall retarded by trees planted in growth height parallel to the window height level

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4.0 CONCLUSION

In designing for the coastal zones of nigeria with particular reference to prototype mass

housing,the designer should give adequate considerations to the fore going guidelines to

create designs that are environmentally friendly,green in nature and facilitate human

comfortability and climatically adaptive.

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References

1. Evans, M. (1980). Housing, Climate and Comfort. The Architectural Press, London.

2. Garba, Shaibu Bala & Salisu, Abubakar Sadiq (1995). Land Management Strategies

For Effective Urban Mass Housing In Nigeria. A paper presented at the Nigerian

Institute of Quantity Surveyours Conference, Kaduna

3. Ogunsote, O.O. (1987). "Climatic Zones for Architectural Design In Nigeria: A

Compendium of Existing Definitions and A Proposal for Their Systematic

Delineation". A Doctoral Seminar paper Presented to the Department of Architecture,

Ahmadu Bello University, Zaria.

4. Olgyay, V. (1963). Design With Climate - Bioclimatic Approach To Architectural

Regionalism.Princeton University Press, Princeton, New Jersey.

5. Martin Clark & BA GradDip T.P (1993) Designing for Climate.

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