East Africa Climatic Data and Guidelines for Bioclimatic Architectural Design

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EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR i BIOCLIMATIC ARCHITECTURAL DESIGN

EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN ii EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

United Nations Human Settlements Programme (UN-Habitat) P. O. Box 30030, 00100 Nairobi GPO KENYA Tel: +254-020-7623120 (Central Office) www.unhabitat.org

DISCLAIMER

The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Views expressed in this publication do not necessarily reflect those of the United Nations Human Settlements Programme, the United Nations, or its Member States.

Excerpts may be reproduced without authorization, on condition that the source is indicated.

This publication was made possible through the financial support of the Global Environment Facility (GEF).

Acknowledgements

Project supervisor: Vincent Kitio Principal author: Jerusha Ngungui Contributors: Ruth Maina Editor: Sue Ball Design and layout: Jerusha Ngungui, Kennedy Muzee Printing: UNON, Publishing Services Section, Nairobi EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR iii BIOCLIMATIC ARCHITECTURAL DESIGN

Table of content executive summary v 1. INTRODUCTION 1 2. sources of climatic data 2 3. climatic data parameters and impact on design 3 4. METHODOLOGY 7 5. CLIMATE CLASSIFICATION 10 6. major cities in east africa 13 6.1 KENYA 14 Eldoret 16 Embu 21 Garissa 26 Kakamega 32 Kisii 37 Kisumu 42 Kitale 48 Lamu 53 Lodwar 59 Makindu 65 Malindi 71 Mandera 77 Meru 83 Mombasa 88 Moyale 95 Nairobi 100 Nakuru 107 Narok 114 Voi 119 6.2 TANZANIA 124 Dar es Salaam 126 Dodoma 133 Mbeya 138 Mwanza 143 Tabora 149 Tanga 154 Zanzibar 160 6.3 UGANDA 165 Kampala 167 6.4 RWANDA 173 Kigali 175 Bibliography 181 appendix 183 iv EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR v BIOCLIMATIC ARCHITECTURAL DESIGN

EXECUTIVE SUMMARY

This report presents climatic data of different regions in East Africa that was compiled within the project Promoting Energy Efficiency in Buildings in East Africa. This project was initiated by UN-Habitat in collaboration with the Governments of Kenya, Uganda, Tanzania, Rwanda and Burundi and the United Nations Environmental Program (UNEP). Funded by the Global Environment Facility (GEF) and co-funded by the five East African countries, the project was designed to help countries in East Africa to integrate energy efficiency measures into their building policies and practices to reduce energy demand.

East Africa is divided into six unique climatic regions – hot and humid e.g. Dar es Salaam, hot-arid e.g. Garissa, hot semi-arid / savannah e.g. Dodoma, great lakes e.g. Kampala, upland e.g. Kigali and high upland e.g. Eldoret - each requiring different design strategies to minimise energy consumption and maximise indoor thermal comfort.

Climatic data for 20 major towns in Kenya was obtained from the open database of the U.S. Department of Energy1 while data from major towns in Tanzania (6), Uganda (1) and Rwanda (1) was obtained under license from Meteotest through the software Meteonorm2. These data sets, which are Typical Meteorological Year (TMY), contain hourly meteorological values for a 1-year period that characterise climatic conditions at a specific location over a long period of time such as 30 years.

The data was analysed and presented graphically (inform of psychrometric charts) using Climate Consultant 6.0 - a graphic based climate data analysis computer program. Microsoft Excel program was also used to generate climate data graphs. From the analysis, it was clear that each zone requires different passive building design strategies to achieve human thermal comfort as well as minimise the energy required for heating and cooling. Some of the interventions that are suited for all the climatic zones include:

• Orientation of the building along the east – west axis with major openings facing north and south. • Protection of all openings using appropriate sun shading devices against unwanted solar radiation. • Provision of openings for natural ventilation and daylighting – large openings are more suitable for hot and humid climates while small openings are preferred in hot arid and hot semi-arid / savannah climates. • Single-banked floor plans in hot humid and great lakes climate to maximise cross ventilation while double-banked building forms are desirable for uplands and high upland climates. • Open layouts are recommended for hot humid and great lakes climates to allow maximum ventilation while compact housing layouts are preferred in hot arid and hot semi-arid / savannah climates for mutual shading and provision of cool spaces when combined with plants and water features as well as protection against hot, dry winds. • Use of light coloured or reflective external surfaces to reflected unwanted solar radiation. • Light weight building envelope is recommended for hot and humid climates to maximise air flow; medium weight building structures are recommended for hot semi-arid / savannah and great lakes climate to even out indoor temperatures; and high thermal mass building materials are preferred for hot and arid climates because of the high daily temperature swing; and medium weight structures are recommended for uplands and high uplands climates for best exploitation of passive solar gains for passive heating.

1 U.S Department of Energy (n.d.) Weather Data | EnergyPlus [Online]. Available from: . 2 Meteotest (n.d.) Meteonorm: Irradiation Data for Every Place on Earth [Online]. Available from: . vi EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 1 BIOCLIMATIC ARCHITECTURAL DESIGN

01 Introduction

In Africa, the building sector alone accounts for over Buildings have a strong potential to negatively or 54% of primary energy. Majority of buildings in sub- positively impact two important elements of everyday life: Saharan Africa are replicas of buildings designed for the environment and energy bills. Their contribution to the western world even though they are in the tropical climate change mitigation on greenhouse gas emission climate. This results to heavy reliance on artificial means and higher or lower energy bills are directly related to the for cooling, heating and lighting. Additionally, tremendous way they are designed in relation to local climate and site- energy wastage is caused by poor understanding of specific characteristics. thermal comfort and passive building principles that leads to inefficient design as well as poor energy conscious The first step in creating thermal comfort in buildings behaviour. is to understand the relationship between the climate and the need for shelter. Buildings are exposed to a wide However, energy saving potentials can be achieved if range of weather parameters throughout the year and this buildings are correctly designed with passive building influences the way they should be designed in relation to strategies that are according to the climate in which they their location. are located, resource efficient appliances are provided and renewable energy technologies are adopted. Knowledge The objective of this report was to: of the climatic conditions of a place is important to develop appropriate designs and consequently select 1. Provide guidelines in the collection and analysis of suitable materials that meet climatic constraints. climatic data;

Climate may be described as the average course or 2. Highlight how the data will assist in energy efficient condition of the weather at a place usually over a period building design; and of years (usually 30 years) as exhibited by patterns of temperature, wind, atmospheric pressure, solar radiation, 3. Define climatic zones in East Africa and present precipitation, humidity and other meteorological variables. climatic data of various towns, giving passive building design recommendations according to the Bioclimatic Architecture is described as a combination climates in which they lie. of design solutions that will create a satisfactory level of human comfort within a building. The building in question should be designed in such a way it works with the climate and natural energy sources; minimise the need for fossil fuel to run; have indoor thermal comfort etc3.

Man responds to buildings, landscapes, trees and other elements as much as he responds to social experience4. However, modern buildings seem not to take into consideration the relationship between man and his behavioural response to the external climatic elements. They have been increasingly designed as copies of western standards with no consideration to the local climate thus the modern design separates the inside from the outside as much as possible, increasingly relying on mechanical devices and systems to do much of the work in creating thermal comfort.

3 ENEA, (Italian Commisssion for Nuclear and Alternative Energy Sources & IN/ ARCH Na) (1983) Architettura Bioclimatica: Bioclimatic Architecture. Rome: De Luca Editore. 4 Konya, A. (1980) Design Primer for Hot Climates. London: Architectural Press. 2 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

02 SOURCES OF CLIMATIC DATA

Climatic data collection iv. open data base

Climatic data can be collected through the following The U.S Department of Energy7 contains an open data ways: base that has weather data for more than 2,100 locations worldwide which is classified by WMO region and country. i. Government Meteorological These data is available in EnergyPlus weather format (.epw) that can be used in conjunction with software available in Stations the market to simulate climatic conditions of a particular location. Some of these tools include Climate Consultant8, The main and most reliable source of climatic data is Autodesk Ecotect9, RETScreen10, DesignBuilder11, from the Governments’ Meteorological Departments. The EnergyPlus12 among others. These building simulation Kenya Meteorological Department5 sells data to private tools are important as they test a building’s response to organizations per parameter per location. For instance, different climatic conditions. temperature data from different weather stations like Nairobi, Mombasa etc. can be purchased separately for v. online sources each month for each town for each climatic parameter. It is important to find out the logistics of collecting data from Numerous websites contain compiled climatic data the Meteorological stations in your respective country. information that has been derived from other sources. Data from such websites should be critically analysed ii. climatic design publications and compared and therefore it is important to verify the sources before they are considered appropriate for use. Books and other publications on climatic design contain climatic data information that has been compiled vi. Airports from various sources. This data, in as much as it may not be as comprehensive as the one obtained from the Many countries use data collected at weather stations meteorological department, may give a general overview located at airports. In Kenya, the airport data collection of the climate of a particular location. These publications centers are connected to the Kenya Meteorological may also give general information on how the climatic Department. Most airports in the region however, tend to parameters have been changing over the years and offer be located a few kilometres from the busy urban centers insight on rare phenomena in an area i.e. mudslides, and the data collected is usually slightly different from the flooding, earthquakes etc. data needed in busy urban centers. A differential factor can be applied to the collected data to obtain relevant iii. Atlases information. An atlas, which is a collection of maps, may contain

reliable climatic data. Organisations that are concerned 7 U.S Department of Energy (n.d.) Weather Data | EnergyPlus [Online]. Available with climate and climate mitigation such as World from: . Meteorological Organization (WMO)6 are good sources of 8 Climate Consultant (n.d.) [Online]. Available from: . 9 http://www.autodesk.com.au/ 10 Natural Resources Canada (2014) RET Screen International Home [Online]. Available from: . 11 DesignBuilder Software Ltd (2015) DesignBuilder - Building Simulation Made 5 Kenya Meteorological Department (2015) Kenya Meteorological Department Easy [Online]. DesignBuilder. Available from: . content/view/43/64/>. 6 World Meteorological Organization (2016) World Meteorological Organization 12 U.S Department of Energy (2015) EnergyPlus Energy Simulation Software Extranet | Www.wmo.int [Online]. Available from: . eere.energy.gov/buildings/energyplus/>. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 3 BIOCLIMATIC ARCHITECTURAL DESIGN

03 Climatic data parameters and impact on design

Designing according to the local climate is not only Global solar radiation, which is measured by economically beneficial through the reduction of energy pyranometers (see Figure 1), is a combination of three bills, but also improves indoor comfort. When designing a components – direct, diffuse and reflected solar radiation building for indoor comfort, the key elements to consider from the ground or surrounding surfaces (as illustrated in are; solar radiation, air temperature, relative humidity, Figure 2). wind (direction, frequency and velocity) and rainfall. The frequency and likely duration and nature of extreme Knowledge of the amount of solar radiation at a location climatic phenomenon must also be ascertained because will influence the building design in terms of the building even though they may be relatively rare and for short form and orientation; location and size of openings; durations, they must be considered to ensure structural appropriate sun shading options; type of glazing; external safety. Such phenomena include earthquakes, lightning, surfaces - choice of materials, type of textures and finishes; landslides, dust storms and floods. insulation materials and location; roof space ventilation etc.

A brief description of the climatic elements listed above b) aIR Temperature and their impact on design is given below. Air temperature, which is a measure of how hot or a) Solar Radiation cold the air is, is the most commonly measured weather parameter. Measured by a thermometer (see Figure 3), This is radiation emitted by the sun in form of it is greatly influenced by geographical factors (latitude, electromagnetic waves, infrared radiation, ultra violet hydrography and topography), surface texture, solar radiation and visible light. As it is the source of almost radiation, wind and location (i.e. rural vs urban setting). all the earth’s energy, it influences most of the climatic Generally, air temperature reaches its lowest value just phenomena. before sunrise and gradually increases to its maximum value in the early afternoon where it begins to decrease.

Figure 1 Pyranometers measure total or Figure 2 WAYS IN WHICH A SURFACE RECEIVES global solar radiation global SOLAR RADIATION

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Source: http://www.hukseflux.com/ Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat. 4 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 3 Indoor / outdoor wall thermometer Figure 5 Wind rose diagram for Mombasa, Kenya.

Source: https://www.weathershack.com

Figure 4 Cup anemometer that measures wind Source: https://www.meteoblue.com/ speed and wind direction Understanding the prevailing wind patterns of the site can be useful when designing ways to take advantage of natural ventilation or to protect the occupants from uncomfortable windy conditions. Knowledge of the wind characteristics of a location will enable the determination of proper building shape and orientation; type, size and position of openings; internal space configuration and siting of buildings on site.

A wind rose diagram (see Figure 5) is used to show wind speed and direction. It also analyses the characteristics of the wind by indicating its strength and frequency over a specified period (month, season and year). The longest spoke on the wind rose represents the greatest frequency of winds blowing from that direction over the specified time frame. Source: http://climate.ncsu.edu/edu/ag/instruments

d) Relative humidity Daily and monthly temperature ranges enable the prediction of heat loss / gain in buildings. This allows the Relative humidity is the ratio of the actual humidity in designer to make appropriate design responses to create a given volume of air to the maximum moisture capacity indoor thermal comfort. at that particular temperature14. It affects the behaviour of building materials and their rate of deterioration. High c) Wind relative humidity quickens the corrosion of metals (such as galvanised iron sheets) and retards evaporation from Wind is the movement of air masses caused by wet surfaces which may lead to warping and cracking of air temperature gradients as well as differences in certain materials (such as timber). atmospheric pressure. Direction, speed and frequency of calms, measured using an anemometer (see Figure 4), are Combined with high temperature, it often results in important characteristics of wind. Natural air movement the growth of surface mould on certain materials for enables natural ventilation which is beneficial in the example concrete and other cement products. It also following ways: maintain the quality of air in buildings affects the evaporation from the human body and thus above a certain minimum level by replacing contaminated has a direct effect on the thermal sensation and comfort15. indoor air with outdoor fresh air; cool the building’s Figure 6 shows a sling psychrometer, a type of instrument structure and promote heat loss from the body thus commonly used to measure relative humidity. 13 providing thermal comfort . 14 Konya, A. (1980) Design Primer for Hot Climates. London: Architectural Press. 15 Hooper, C. (1975) Design for Climate: Guidelines for the Design of Low Cost 13 Hooper, C. (1975) Design for Climate: Guidelines for the Design of Low Cost Houses for the Climate of Kenya. Nairobi: Housing Research and Development Houses for the Climate of Kenya. Unit, University of Nairobi. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 5 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 6 A sling psychrometer (consisting of a wet-bulb thermometer and a dry-bulb thermometer) is largely used to determine relative humidity

Source: http://www.physicalgeography.net/fundamentals/8c.html e) Rainfall

Rainfall results from condensed water vapour that affecting the micro climate. This in turn influences the precipitates forming droplets that fall from clouds due design of the building and therefore proper site analysis is to gravity. The rate, intensity and amount of rainfall required to maximize the use of the existing micro climate. determines the drainage requirements, waterproofness of a structure, choice of roof pitch, size of roof overhangs, 2. longitude and Latitude size of gutters, durability of walls etc. Rainfall is measured using a rain gauge (see Figure 7). The geographic location of a place can be identified using longitude and latitude coordinates. One of the most Other factors that do not constitute climatic parameters important factors that affect climate is the latitude. The but influence the building design include: distance from the sun varies with the distance a site is in relation with the equator (latitude 0°). The further a site 1. Topography is from the equator, the longer it takes for the sun rays to reach the surface. This affects solar radiation, temperatures, The natural features of a location / site such as the precipitation and on some occasions humidity. This shape, orientation, altitude of hills, valleys, presence or influences a building’s orientation, sun shading, size of absence of water bodies, vegetation etc. have an effect of openings, type of glazing, building material etc. temperature, solar radiation, wind and rainfall therefore The sun’s changing position in the sky throughout the Figure 7 A rain gauge year can be conveniently represented by the sun path diagram (see Figure 8). It is represented with a coordinate system (altitude and azimuth) and can be read off directly from the diagram for any time of the day and month. This is useful in providing a summary of the solar position that should be considered when designing. The most used systems are the polar and the cylindrical sun path diagrams.

Polar sun path diagram The polar representation gives the image of the celestial sphere by placing itself right above the zenith (the point of the sky directly overhead) of the area under consideration. In this type of representation, lines of equal solar altitude are spaced widely apart near the zenith of the sky but are concentrated quite closely together near the horizon. Each sun-path line is generated by determining the exact position of the sun as it passes through the sky (hourly) for each date. This is then projected from the sky dome onto Source: http://www.windandweather.com/ the flat image (see Figure 8). 6 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 8 Polar sun path diagram for Latitude 0° (E.g. Eldoret town 0° 31’ N 35° 17’ E)

Reading the Position of the Sun (altitude and To find the optimal building orientation, place the azimuth) building plan in the centre of the diagram, aligning it with the orientation under consideration. 1. Select the chart of the correct latitude (each location has a different chart).

2. Select one date line to be analysed.

3. Select the hour line and mark its intersection with the date line.

4. Read from the concentric circles the altitude angle (sun’s height from the ground).

5. Lay a straight line from the centre of the chart, through the marked time point to the outer circle and read the azimuth angle (sun orientation related to the north). EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 7 BIOCLIMATIC ARCHITECTURAL DESIGN

04 METHODOLOGY

For useful energy efficiency design measures to be put i. Mahoney tables in place, it is important to have hourly parameters over a 24-hour period, 1-week period, and 1-month period Mahoney tables, named after architect Carl Mahoney, and so on. This report is an attempt to utilise the data are a set of reference tables used in architecture as a most readily available for the designers that will assist in guide to climate-appropriate design. They consist of tables preliminary design measures given the recorded averages that use readily available climate data – temperature, of the climatic parameters. relative humidity, rainfall and wind - for comparison with requirements for thermal comfort appropriate design Climatic data collection in some of the East African criteria. A sample of these tables are as seen in Appendix 1. countries like Kenya is expensive and difficult to get from the appropriate authorities which would make it ii. olgyay’s bioclimatic chart increasingly difficult for individual designers to access important data to carry out their work. Considering the This is a simple tool for analysing climate by indicating importance and necessity of these data to designers, it is human comfort zones based on ambient temperature, paramount that it be more accessible to the professionals humidity, mean radiant temperature, wind speed, solar either through the relevant professional associations or the radiation and evaporative cooling (see Figure 9). Based on relevant bodies that provide the data. dry bulb temperature and relative humidity, a point on the chart can be determined if it lies within the comfort zone. Any point that falls beyond the comfort zone region, then a) climatic data presented in this corrective measures are required to restore the feeling of report comfort.

Climatic data presented in this report was obtained iii. Givoni’s bioclimatic chart from the open database of the U.S Department of Energy 16which contains Typical Meteorological Year (TMY) files The Givoni bioclimatic chart shows air temperature for more than 2,100 locations of the world. (represented by vertical lines) against relative humidity, (represented by curved lines) and can be used to express Weather files for towns in Kenya presented in this report human thermal comfort, design strategies, and energy were obtained from this data base. Other weather files - requirements for those strategies. Tanzania, Uganda and Rwanda - files were obtained under license from Meteotest through the software Meteonorm17. This chart suggests design strategies to adapt a building’s These TMY data sets contain hourly meteorological values architecture to the prevailing climate according to six for a 1-year period that characterise climatic conditions at zones that are defined on the chart as shown in Figure 10. a specific location over a long period of time such as 30 These zones include: years. 1. Comfort zone b) analysing climatic data This is defined as the range within which occupants are Different approaches can be used to determine passive satisfied with the surrounding conditions. Thermal comfort design strategies for different climatic conditions. These is experienced when the boundaries of air temperature are include: between 20 and 26 °C while relative humidity is between 20 and 80%.

16 U.S Department of Energy (n.d.) Weather Data | EnergyPlus [Online]. Available from: . 17 Meteotest (n.d.) Meteonorm: Irradiation Data for Every Place on Earth [Online]. Available from: . 8 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 9 Olgyay’s bioclimatic chart that is mostly applicable to outdoor conditions

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat.

2. natural ventilation zone 5. High thermal mass and night In cases where the air temperature exceeds 26 °C or ventilation zone relative humidity is quite high (above 50%), natural Thermal mass in conjunction with night ventilation can ventilation can improve the thermal comfort. This extends be used to provide cooling in situations where the diurnal the thermal comfort up to an outdoor air temperature temperature swing is high and the night time temperature limit to 32 °C. On the other hand, in conditions where the falls below 20 °C. temperature exceeds 26 °C and relative humidity is below 50%, night cooling would be more appropriate than day 6. Passive heating zone ventilation. Where the air temperature is lower than 20 °C, the use of passive solar heating is suitable for extending the 3. eVaporative cooling zone thermal comfort zone. Other strategies include use of When the air temperature is high and relative humidity insulation. is low, water vapour can be used to extend the thermal comfort zone by reducing air temperature and increasing This report focuses on the Givoni bioclimatic chart in the relative humidity of a space. analysing the Typical Meteorological Year climatic data of the representative cities / towns as obtained from the open database of the U.S Department of Energy19. 4. High thermal mass zone High thermal mass can be used in a building to reduce variation in indoor temperature compared to outdoor temperature as well as reducing peaks in conditions of high diurnal temperature swing18.

18 A diurnal temperature swing is the cycle of temperatures over the course of 19 U.S Department of Energy (n.d.) Weather Data | EnergyPlus [Online]. Available one 24-hour period from: . EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 9 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 10 Givoni psychrometric chart

This psychrometric chart representing Dar es Salaam, Tanzania shows that most hourly data points fall to the right of the comfort zone.

This means that air temperature can be reduced by increasing air flow with natural ventilation.

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat. c) Software used in this report

Climatic data for a given site - outdoor temperatures and relative humidity (monthly, daily or hourly) - can be plotted onto a psychrometric chart to determine which of the above zones the plotted conditions fall into.

Various software have been developed to suggest the best strategies for improving thermal comfort conditions based on the plotted climatic data. For this report, Climate Consultant20 was used to generate psychrometric charts – which is a graphical representation of the relationship between air temperature and relative humidity. This helps to describe the climatic data and human thermal comfort conditions. Weather data files – obtained from the open database of the U.S. Department of Energy were uploaded into Climate Consultant resulting to data points for every hour of the year as seen in Figure 10 . The density of the data points on the chart decipher the average conditions enabling one to consider the most suitable passive design strategies to extend the thermal comfort zone.

20 Climate Consultant (n.d.) [Online]. Available from: . 10 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

05 CLIMATE CLASSIFICATION

World climate classification D. cold climate

The Köppen-Geiger Climatic Classification System is Most of these zones are located between the latitudes the most widely used system to characterise the world’s 40° - 70° N and are characterised by cool summers and climatic conditions. Its categories are based on the monthly cold winters. In the warmest months, these climates have and annual averages of precipitation and temperature. an average of temperatures above 10° C and during the According to the classification, the world is divided into 5 cold months, the temperatures average below -3° C. major climatic zones: E. polar climate A. equatorial climate (Tropical These climates, located between 60° N and the poles, moist) are characterised by average temperatures below 10° C throughout the year. This tropical climate zone with little seasonal variation, extends from 15° N to 15° S. It comprises of 3 sub-climates The East African region falls within the boundaries of within it: tropical wet and humid climate, characterised by the Equatorial climate which extends from 15 °N and monthly average temperatures ranging between 24 – 30° 15 °S. However, a wide range of climatic conditions are C and abundant rainfall with total annual amounts of over experienced within the region as illustrated in Figure 11. 2000 mm; tropical monsoon and savannah, characterised These can be divided into 6 climatic zones namely : by distinct wet and dry periods. Zone 1: Hot-humid B. aRId climate (dry) Zone 2: Hot arid This climatic zone is located between latitudes 15° – 30° N and 15° – 30° S and is characterised by very hot summer Zone 3: Hot semi-arid /Savannah seasons and cooler winter seasons. They also experience high diurnal temperature. Zone 4: Great Lakes

Hot desert regions are characterised by high monthly Zone 5: Upland and annual temperature (maximum temperatures of 40 - 45° C are common) with high diurnal temperature ranges; Zone 6: High upland low relative humidity and cloud cover; low amount of rainfall (less than 25 mm per year) and high wind speeds Table 1 gives a summary of the general characteristics of the 6 climatic zones in East Africa as well as representative On the other hand, cold desert regions are characterised cities / towns of each. by low relative humidity and cloud cover; moderate monthly and annual temperatures; low amount of rainfall that occurs infrequently.

C. Temperate climate The temperate climates are generally located between 40 – 60° N and are characterised by seasonal changes between summer and winter without extremes of temperature and precipitation. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 11 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 11 Climatic zones of East Africa

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat. 12 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

TABLE 1 Characteristics of the major climatic zones in East Africa

ZONE NAME CHARACTERISTICS REPRESENTATIVE CITIES Zone 01 Hot humid / Hot • Location: 0 – 100 km wide strip from the ocean coast Lamu, Kenya and semi-humid • Altitude: <300m above sea level Malindi, Kenya • Mean air temperature range: 25 – 32°C with a mean temperature Mombasa, Kenya swing of 3 – 7°C Dar es Salaam, Tanzania • Average annual rainfall: 900 -1,250mm Tanga, Tanzania • Mean relative humidity: approximately 80% around the coastline. From 20 - 100km, the relative humidity is 65 - 72% • Global solar radiation: 5.0 - 5.4kWh/m2. It lowers one moves away from the coastline to 4.5kWh/m2 Zone 02 Hot arid • Altitude: range from 0 m – 500 m above sea level Garissa, Kenya • Mean air temperature range: 23 – 36°C with a mean temperature Lodwar, Kenya swing of 12°C • Average annual rainfall: 0 – 500 mm • Mean relative humidity: approximately 40% • Global solar radiation is around 7.0kWh/m2 Zone 03 Hot semi-arid / • Altitude: ranges from 500 – 1,000 m above sea level in semi-arid Isiolo, Kenya Savannah areas and rises to 1,500 m in the savannah plains Machakos, Kenya • Mean air temperature range: 20 – 22°C and can rise to a mean temperature range of 29 – 31°C. In the semi-arid areas, the Mavoko, Kenya temperatures can go up to 33°C Thika, Kenya • Average annual rainfall: 50 – 750mm in semi-arid areas to 1,000 – Dodoma, Tanzania 1,500mm in savannah regions Tabora, Tanzania • Mean relative humidity: 65% but can go as low as 42% in parts of the savannah plains Gulu, Uganda • Global solar radiation: 6.3kWh/m2 Iganga, Uganda Kabale, Uganda Kasese, Uganda Lira, Uganda Zone 04 Great Lakes • Location: 0 - 25km wide strip along lake shores Homabay, Kenya • Mean air temperature range: 16 – 29°C Kisumu, Kenya • Average annual rainfall: >1,200mm Mwanza, Tanzania • Mean relative humidity: 60 - 70% Jinja, Uganda • Global solar radiation: 5.5kWh/m2 Kampala, Uganda Kibuye, Rwanda Bujumbura, Burundi Zone 05 Upland • Altitude: 1,500 – 2,000 m above sea level Kitale, Kenya • Mean air temperature range: 14 – 24°C. In the hot period, Nairobi, Kenya temperature range is about 26 – 27°C Nakuru, Kenya • Average annual rainfall: >1,250mm Arusha, Tanzania • Mean relative humidity: 65 – 75% Mbeya, Tanzania • Global solar radiation: around 5.0 – 6.0 kWh/m2 Fort Portal, Uganda Mbale, Uganda Kigali, Rwanda Zone 06 High upland • Altitude: >2,000 m above sea level Eldoret, Kenya • Mean air temperature range: 12 – 20°C • Average annual rainfall: >1,200mm • Mean relative humidity: 80% • Global solar radiation: 5.3 kWh/m2 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 13 BIOCLIMATIC ARCHITECTURAL DESIGN

06 MAJOR CITIES IN EAST AFRICA

Climatic data information representing 28 locations spread over the 6 climatic zones across East Africa are presented in the following sections. This information brings together data on the main climatic elements namely:

• air temperature • relative humidity • solar radiation • rainfall and • wind table 2 East African cities / towns presented

ZONE CHARACTERISTICS Kenya Eldoret, Embu, Garissa, Kakamega, Kisii, Kisumu, Kitale, Lamu, Lodwar, Makindu, Malindi, Mandera, Meru, Mombasa, Moyale, Nairobi, Nakuru, Narok, Voi Tanzania Dar es Salaam Dodoma Mbeya Mwanza Tabora Tanga Zanzibar Uganda Kampala Rwanda Kigali 14 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

6.1 KENYA

Figure 12 Map of Africa showing the location of Kenya

Source: http://www.d-maps.com/ EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 15 BIOCLIMATIC ARCHITECTURAL DESIGN

table 3 Representative towns in Kenya

CITY/TOWN ALTITUDE (M) LATITUDE LONGITUDE CLIMATE ZONE

Eldoret 2,085 m 0° 31’ N 35° 16’ E High upland Embu 1,350 m 0° 32' S 37° 27' E Upland Garissa 147 m 0° 28’ S 39° 38’ E Hot arid Kakamega 1,500 m 0° 27’ S 34° 43’ E Upland Kisii 1,700 m 0° 41' S 34° 46' E Upland Kisumu 1,135 m 0° 05’ S 34° 45’ E Great lakes Kitale 1,900 m 1° 01’ N 34° 59’ E Upland Lamu 308 m 2°16’ S 40° 54’ E Hot humid Lodwar 477 m 3° 07’ N 35° 36’ E Hot arid Machakos 1,138 m 1° 30’ S 37° 15’ E Hot semi-arid / Savannah Makindu 1,070 m 2° 16' S 37° 49' E Hot semi-arid / Savannah Malindi 23 m 3° 13’ S 40° 07’ E Hot humid Mandera 231 m 3° 55’ N 41° 50’ E Hot arid Meru 1,582 m 0° 05’ N 37° 38’ E Upland Mombasa 55 m 4° 03’ S 39° 40’ E Hot humid Moyale 850 m 3° 30' N 39° 40' E Hot arid Nairobi 1,789 m 1°16’ S 36° 48’ E Upland Nakuru 1,850 m 0° 16’ S 36° 04’ E Upland Narok 1,827 m 1° 05’ S 35° 52’ E Upland Nyeri 1,768 m 0° 25’ S 36° 57’ E Upland Voi 580 m 3° 23’ S 38° 34’ E Hot arid 16 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

ELDORET

Figure 13 Location of Uasin Gishu Climatic Zone UPLAND county Latitude 00° 31’ N Longitude 35° 16’ E Altitude 2,085 m

Figure 14 aErIAl view of eldoret town

Source: http://www.d-maps.com/ Source: Google map images © Sir Ray KILIMO

Figure 15 Location of Eldoret town in Uasin Gishu county

GEOGRAPHY AND bioclimatic data It also experiences relatively cool temperatures with mean air temperatures averaging 16.9 °C. The coolest month of Eldoret, the largest town in Uasin Gishu county, has grown the year is July while the highest average temperature is to become the fifth largest town in Kenya - after Nairobi, recorded in February. Relative humidity averages at 70% Mombasa, Kisumu and Nakuru. It is located at geographic annually while the wind velocity ranges 2.1 – 4.6 m/s with coordinates of 0° 31’ N, 35° 17’ E at an average altitude the predominant wind direction being East North East of 2,085 m above sea level. The town receives over 1, 082 (ENE). The annual average global solar radiation in Eldoret mm of annual rainfall with the highest amount received is 5.8 kWh/m2. in the months of August and the least amount in January. table 4 Eldoret monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 17.8 58.0 3.3 6.2 6.1 2.1 30 FEB 18.5 53.0 4.6 6.4 5.9 2.3 50 MAR 18.2 62.0 3.4 6.2 5.2 2.3 70 APR 17.1 74.0 3.4 5.6 4.0 2.6 150 MAY 16.7 73.0 2.7 5.5 4.4 2.4 140 JUN 16.1 77.0 2.4 5.3 4.2 2.4 120 JUL 15.3 80.0 2.7 5.0 3.6 2.5 160 AUG 15.9 78.0 2.1 5.3 3.8 2.6 180 SEPT 16.3 75.0 2.6 6.2 5.0 2.5 100 OCT 17.0 72.0 3.0 5.9 4.6 2.5 60 NOV 17.0 69.0 4.1 5.5 4.0 2.6 60 DEC 16.7 66.0 4.1 5.9 5.2 2.4 40

Figure 16 Monthly mean maximum and minimum temperature for Eldoret T-MiN T-MAX eldoret 40 35 30 24.9 23.2 24 25 22.3 22 22.3 21.9 21.5 21 21.1 19.9 20.7 C]

° 20 [ 13.3 13.8 13.8 12.7 12.7 13.4 12.7 15 12.4 11.1 11.9 11.6 11.8 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 17 monthly mean relative humidity for Eldoret rH-MiN rH-MAX eldoret 93 94 94 100 91 91 89 87 85 80 81 83 76 80 61 56 54 56 60 50 50 47 48 46

[%] 37 37 40 27 20

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 18 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 18 Monthly average rainfall for Eldoret

rAiNFALL eldoret 350 300 250 180 200 160 150 140 [mm] 150 120 100 100 70 60 60 50 40 50 30 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 19 Polar sun path diagram for Latitude 0° (Equator) EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 19 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 20 Wind rose diagram showing the prevailing wind direction in Eldoret

Figure 21 Psychrometric chart with passive design strategies overlays for Eldoret

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 20 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive solar gains by The hourly outdoor dry bulb and relative humidity storing heat accumulated during the day (avoiding data points indicate that Eldoret falls within the comfort overheating) to balance the night time low zone during certain periods of the year (see Figure 21). temperatures to keep them at comfort level. However, for a substantial period, the temperatures are • Excessive glazing should be avoided as it can lead to clearly below comfort with temperatures getting to below overheating during the hot period as well as lead to 10 °C at certain times. This means that the main design extensive heat loss at night or during the cold periods. objective should be to increase indoor temperatures to • All windows should be airtight to prevent heat losses comfort levels. The chart therefore shows that passive when the outdoor temperatures are below the heating through direct solar heat gain and thermal mass comfort zone and they should be located on opposite is therefore the most essential strategy for extending the walls to allow for cross-ventilation. thermal comfort zone during this under heated period. In addition, internal heat gain from equipment, lights and • Additional heating systems such as fireplaces can be occupants provide a valuable source of heat contribution incorporated in the design. to space heating. • Internal heat gains from occupants, equipment and lights will greatly reduce heating needs.

Bioclimatic recommendations b. Protection against heat gain in the hot According to the climatic data for Eldoret, the following period design strategies are recommended for: • Buildings should be oriented with the main glazed a. Enabling passive heating windows facing north and south for easier sun control and to minimise overheating during the hot periods. • Careful orientation of buildings with main rooms • Large windows should be avoided on the east and facing north east is appropriate to allow a certain west facing façades. amount of solar radiation to penetrate for passive heating during the cold periods. • Appropriate sun shading devices should be incorporated to keep out the solar radiation and glare • The floor plan should be organised such that it allows during certain hours of the day during the hot periods the sun to penetrate daytime spaces during the cold (Figure 22). periods. • Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold periods.

Figure 22 Large overhangs provide shading to the glazed north facing façade

Eldoret international airport Source: https://kaa.go.ke/airports/our-airports/eldoret-international-airport/ (left) http://www.jamiiforums.com/ (right) EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 21 BIOCLIMATIC ARCHITECTURAL DESIGN

EMBU

Figure 23 Location of EMBU county Climatic Zone UPLAND Latitude 00° 32’ N Longitude 37° 27’ E Altitude 1,350 m

Figure 24 View of a street in Embu town

Source: http://www.d-maps.com/ Source: http://www.nation.co.ke/ © Charles WANYORO

Figure 25 Location of Embu town in Embu county

GEOGRAPHY AND bioclimatic data February while the coolest month is July. Relative humidity averages at 72.4% annually while the wind velocity ranges Embu town, which serves as the headquarters of Embu 1.1 – 2.9 m/s with the predominant wind direction being County, is located at the foothills of Mt. Kenya at geographic South East. The annual average global solar radiation in coordinates of 0° 32’ S, 37° 37’ E. It is elevated at 1,350 Embu is 5.1 kWh/m2. m above the sea level. The town receives an annual rainfall of 893 mm with the wettest month on average being April while the driest month being August. The average temperature for Embu is 18.9 °C – the warmest month is

table 5 EMBU monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 19.5 70.0 2.9 6.2 5.3 2.5 41 FEB 20.7 63.0 2.9 6.5 5.7 2.4 34 MAR 20.6 64.0 2.1 5.9 4.2 2.7 64 APR 19.6 78.0 1.4 5.1 2.9 2.9 218 MAY 19.1 78.0 1.5 4.6 2.9 2.5 139 JUN 17.8 77.0 1.3 4.0 2.3 2.4 21 JUL 17.0 74.0 1.1 3.7 1.7 2.5 28 AUG 17.1 74.0 1.3 4.2 2.1 2.6 11 SEP 18.9 67.0 1.6 5.1 3.2 2.6 17 OCT 19.4 68.0 1.9 5.2 3.3 2.7 86 NOV 18.5 81.0 2.0 4.8 2.8 2.8 189 DEC 18.9 75.0 2.6 5.5 4.2 2.6 45

Figure 26 Monthly mean maximum and minimum temperature for EMBU T-MiN T-MAX embu 40 35

30 25.8 25.8 25.1 24.2 24 24.7 25 23.2 21.9 22.9 20.8 19.9 20.8 C]

° 20 16.5 [ 15.5 15.8 16 15.5 15.3 14.3 15.2 14.4 13.8 14.8 14.8 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 27 Monthly mean relative humidity for EMBU rH-MiN rH-MAX embu

100 91 91 90 90 89 91 92 84 85 87 86 79 80 67 60 63 61 62 58 56 60 52 47 46 42 45 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 23 BIOCLIMATIC ARCHITECTURAL DESIGN

FigurE 28 Monthly average rainfall for EMBU

rAiNFALL embu 350 300

250 218 189 200 139 [mm] 150 86 100 64 45 41 34 28 50 21 11 17 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 29 Polar sun path diagram for Latitude 0° (Equator) 24 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 30 Wind rose diagram showing the prevailing wind direction in EMBU

Figure 31 Psychrometric chart with passive design strategies overlays for EMBU

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 25 BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive solar heating by The hourly outdoor dry bulb temperatures and relative storing heat accumulated during the day (avoiding humidity points, as seen in Figure 29, indicate that most overheating) to balance the night time low of the time the region is within the comfort zone band. temperatures to keep them at comfort level. For the hours beyond this zone, thermal mass that stores • Excessive glazing should be avoided as it can lead to solar heat gain can be used to enable thermal comfort by overheating during the hot period as well as lead to ensuring cool interiors during day time. extensive heat loss at night or during the cold periods. • All windows should be airtight to prevent heat losses However, a substantial number of hours fall below the when the outdoor temperatures are below the comfort zone making heating necessary most of the time. comfort zone and they should be located on opposite Therefore, the most suitable strategy to extend the limit of walls to allow for cross-ventilation. comfort during the under heated period is through passive solar heating through direct solar heat gain and thermal • Additional heating systems such as fireplaces can be mass. In addition, internal heat gain from equipment, incorporated in the design. lights and occupants are also helpful in extending the • Internal heat gains from occupants, equipment and thermal comfort and reducing heating demand. lights will greatly reduce heating needs.

b. Protection against heat gain in the hot Bioclimatic recommendations period According to the climatic data for Eldoret, the following design strategies are recommended for: • Buildings should be oriented with the main glazed windows facing north and south for easier sun control a. Enabling passive heating and to minimise overheating during the hot periods. • Large windows should be avoided on the east and • Careful orientation of buildings with main rooms west facing façades. facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive • Appropriate sun shading devices should be heating during the cold periods. incorporated to keep out the solar radiation and glare during certain hours of the day during the hot • The floor plan should be organised such that it allows periods. the sun to penetrate daytime spaces during the cold periods. • Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold periods. 26 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

GARISSA

Figure 32 Location of GARISSA county Climatic Zone HOT ARID Latitude 00° 27’ S Longitude 39° 38’ E Altitude 147 m

Figure 33 Garissa town centre

Source: http://www.d-maps.com/ Source: http://www.bauck.com/garissa/

Figure 34 Location of Garissa town in Garissa county

GEOGRAPHY AND bioclimatic data rainfall with the highest amount received in the months of April and November (average of 70 mm). Relative Garissa town, the commercial and administrative hub humidity ranges 54 - 69% annually while the wind velocity of Garissa county, is located at geographic coordinates of averages at 4.0 m/s with the predominant wind direction 0° 27’ S, 39° 39’ E at an altitude of 147 m above sea being South South East (SSE). High wind velocity of 6.5 level. Being in an arid climate, the town experiences high m/s is recorded in June. The annual average global solar temperatures with an annual average of 28.3 °C. The radiation in Garissa is 5.3 kWh/m2. hottest month recorded is March and the coolest month is July. The town receives an average of 260 mm of annual table 6 GARISSA monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 29.2 62.0 2.9 5.3 3.4 2.9 10 FEB 30.1 54.0 2.5 5.8 3.9 2.9 0 MAR 30.3 58.0 3.4 5.7 3.6 3.0 30 APR 29.0 67.0 3.4 5.4 3.1 3.1 70 MAY 28.4 65.0 4.3 5.1 3.5 2.7 10 JUN 27.0 63.0 6.5 5.0 3.4 2.6 0 JUL 26.6 60.0 6.1 4.9 3.2 2.6 0 AUG 26.2 64.0 4.8 5.0 3.1 2.8 0 SEP 27.5 59.0 5.0 5.5 3.4 2.9 0 OCT 28.6 59.0 4.2 5.4 3.5 2.8 20 NOV 28.5 69.0 2.4 5.1 3.0 2.9 70 DEC 28.7 64.0 2.3 4.9 2.8 2.9 50

Figure 35 Monthly mean maximum and minimum temperature for GARISSA T-MiN T-MAX garissa 40 36.1 35.6 34 34.3 33.4 34.3 33.6 35 31.8 33.1 33.2 31.5 30.3 30 25.8 24.5 24.7 25.3 24 23.9 24.7 24.6 25 22.7 23.2 22.4 22.8 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 36 Monthly mean relative humidity for GARISSA rH-MiN rH-MAX garissa 100 86 86 87 82 83 84 83 85 80 81 78 81 80

60 49 45 44 43 45 46 43 [%] 37 39 36 39 40 31

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 28 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 37 Monthly average rainfall for GARISSA

rAiNFALL garissa 350 300 250 200

[mm] 150

100 70 70 50 50 30 20 10 0 10 0 0 0 0 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 38 Polar sun path diagram for Latitude 0° (Equator) EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 29 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 39 Wind rose diagram showing the prevailing wind direction in GARISSA

Figure 40 Psychrometric chart with passive design strategies overlays for GARISSA

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 30 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation walls are effective in reflecting solar radiation thus minimising solar heat gains and consequently The psychrometric chart (see Figure 40) shows that minimising internal daytime temperatures. Garissa is predominantly hot throughout the year with outside conditions (dry bulb temperature and relative b. To counter low relative humidity humidity) falling beyond the comfort zone. Therefore, buildings need much more cooling and no heating at • Evaporative cooling is recommended in this all. It also shows that at certain periods, relative humidity climate to improve the microclimate by elevating in this town is low, especially when the temperatures the humidity level while at the same time cooling exceed 30 °C. Based on the psychrometric chart, the the surrounding air. The following strategies are most appropriate cooling strategies to extend the limit of recommended: fountains, spray ponds, water comfort include the following: shading, natural ventilation, surfaces, moistened fabrics, sprinklers or porous high thermal mass with night ventilation (night flushing) pots etc. and evaporative cooling. • Use of vegetation is effective in improving the However, some days are too hot and dry for the passive air quality by reducing the air temperature as strategies to work successfully. Therefore, convectional well as elevate the humidity level because of the cooling and humidification may be necessary during the evaporative cooling effect of plants (Figure 42). overheated period to maintain thermal comfort. c. To balance diurnal temperature range

Bioclimatic recommendations • Heavy weight building materials with high thermal The design objectives for Garissa should be to reduce capacity are recommended to balance temperature uncomfortable conditions created by intense solar variations between day and night. These heat radiation, low relative humidity, large diurnal temperature storing materials keep daytime temperatures down. range and dusty hot winds. The following design strategies are recommended: • Because of heat absorption qualities of the ground, earth-sheltered and underground housing are a. To reduce effects of intense solar radiation suited for this climate.

• Compact layout of buildings is recommended to d. To ensure air circulation provide mutual shading and minimise exposure to solar radiation. • Openings should be located to take advantage of prevailing winds and allow for cross-ventilation. • Courtyard design of buildings minimises the impact of solar radiation on the outer walls as well as • Ventilation through windows should be kept at a provide cool spaces within the buildings / building minimum during the daytime to keep hot and dusty layout. This increases the daytime cooled spaces air out. This also minimises heat gains. However, at (Figure 41). night, windows may be opened to provide adequate ventilation for dissipation of heat accumulated • Buildings should be oriented along the east – west during the day by walls and the roof to prevent axis with the longer sides facing north and south to overheating of the interior space. prevent solar heat gains. The building’s surface area exposed to the east and west should be minimised. • Other ventilation strategies include use of wind catchers, wind towers, solar chimneys, roof- • Openings should be located on the north and south mounted exhaust fans, high level vents etc. facing façades. Small openings that are located high on the walls are recommended to facilitate e. To minimise problems associated with dust natural ventilation as well as reduce glare from light reflected from the ground or surrounding buildings. • Vegetation can be used to filter dust from the air before it gets into the building. • Appropriate shading devices are necessary on all openings to minimise heat gain from solar radiation. • Closing windows during daytime prevents dust from Use of vegetation, verandas, covered walkways, getting into the building on windy days. Windows pergolas etc. is recommended to provide shade to should be tight-fitting as possible to prevent dust walls, openings and outdoor spaces. from infiltrating.

• Use of reflective surfaces (roof) and light-coloured EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 31 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 41 Examples of courtyard design with vegetation, lightly coloured external finishes and mutual shading of buildings

Almond resort hotel, Garissa Source: http://www.almond-resort.com/

Figure 42 Use of vegetation for landscaping

Almond resort hotel, Garissa Source: http://katharow.blogspot.co.ke/ / Amb. Abdikadir Aden HASSAN 32 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

kakamega

Figure 43 Location of KAKAMEGA Climatic Zone UPLAND county Latitude 00° 17’ N Longitude 34° 45’ E Altitude 1,500 m

Figure 44 View of Kakamega town hall

Source: http://www.d-maps.com/ Source: http://www.nation.co.ke/counties/1107872-1200334-3ktljez/index.html © Isaac WALE Figure 45 Location of Kakamega town in Kakamega county

GEOGRAPHY AND bioclimatic data hottest month of the year while July is the coolest. Relative humidity averages at 76% annually while the wind velocity Kakamega town is the headquarters of Kakamega ranges 1.4 – 2.0 m/s with the predominant wind direction county – the most populous county after Nairobi city. It being East North East (ENE). The annual average global lies at geographic coordinates of 0° 17’ N, 34° 45’ E at solar radiation in Kakamega is 5.9 kWh/m2. an altitude of 1,500 m above sea level. The town receives an annual rainfall of 1,394 mm with the greatest amount occurring in April and the lowest in January. The average temperature in Kakamega is 19.6 °C. January is the table 7 KAKAMEGA monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 21.1 64.0 1.8 6.3 6.0 2.1 64.7 FEB 21.0 66.0 2.0 6.5 5.8 2.2 89.7 MAR 20.5 76.0 1.7 6.2 4.9 2.5 156.1 APR 19.9 80.0 1.7 5.6 4.2 2.5 211.7 MAY 19.1 85.0 1.4 5.4 4.0 2.4 182.4 JUN 19.0 81.0 1.9 5.4 4.4 2.2 87.2 JUL 18.4 79.0 1.5 5.4 4.2 2.4 70.8 AUG 18.5 80.0 1.8 5.8 4.3 2.5 104.2 SEP 18.8 77.0 1.6 6.2 4.9 2.4 97.6 OCT 19.0 78.0 1.6 6.0 4.5 2.6 92.2 NOV 19.5 78.0 1.8 5.6 4.2 2.6 140.3 DEC 20.7 68.0 2.0 6.1 5.7 2.2 97.5

Figure 46 Monthly mean maximum and minimum temperature for KAKAMEGA T-MiN T-MAX KaKamega 40 35 30 26.9 26.2 26.5 26.6 24.7 24 25.2 24 24.1 25.3 24.1 24 25 C]

° 20 16.7 16.2 [ 15.9 16.1 16 15.2 14.6 15.2 14.4 15.5 15.7 15.3 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 47 Monthly mean relative humidity for KAKAMEGA rH-MiN rH-MAX KaKamega 96 98 97 97 96 100 93 95 92 93 87 84 83 80 65 60 55 55 57 58 60 51 54 51 47 41 41 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 34 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 48 Monthly average rainfall for KAKAMEGA

rAiNFALL KaKamega 350 300

250 211.7 200 182.4 156.1 140.3 [mm] 150 104.2 89.7 87.2 97.6 92.2 97.5 100 64.7 70.8 50 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 49 Polar sun path diagram for Latitude 0° (Equator) EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 35 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 50 Wind rose diagram showing the prevailing wind direction in KAKAMEGA

Figure 51 Psychrometric chart with passive design strategies overlays for KAKAMEGA

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 36 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive heating by The psychrometric chart (see Figure 51) shows that storing heat accumulated during the day (avoiding Kakamega is predominantly cool with outdoor conditions overheating) to balance the night time low of hourly dry bulb temperatures and relative humidity temperatures to keep them at comfort level. falling within as well as below the comfort zone. This indicates that heating is necessary during the under • Excessive glazing should be avoided as it can lead heated period. The chart therefore suggests that the most to overheating during the hot period as well as lead effective strategy for extending the thermal comfort zone to extensive heat loss at night or during the cold would be passive heating through direct solar heat gain periods. and thermal mass. In addition, internal heat gain from occupants, equipment and lights would contribute to a • All windows should be airtight to prevent heat reduction in heating needs. losses when the outdoor temperatures are below the comfort zone and they should be located on However, during certain times of the year, the hourly opposite walls to allow for cross-ventilation. data points (outdoor dry bulb temperature and relative humidity) fall beyond the comfort zone. Thermal mass is • Additional heating systems such as fireplaces can be effective in extending the comfort zone by absorbing and incorporated in the design. storing daytime solar heat for release at night when the temperatures fall below the comfort zone. • Internal heat gains from occupants, equipment and lights will greatly reduce heating needs.

Bioclimatic recommendations b. Protection against heat gain in the hot According to the climatic data for Kakamega, the period following design strategies are recommended for: • Buildings should be oriented with the main glazed a. Enabling passive heating windows facing north and south for easier sun control and to minimise overheating during the hot • Careful orientation of buildings with main rooms periods. facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive • Large windows should be avoided on the east and heating during the cold periods. west facing façades.

• The floor plan should be organised such that it • Appropriate sun shading devices should be allows the sun to penetrate daytime spaces during incorporated to keep out the solar radiation and the cold periods. glare during certain hours of the day during the hot periods. • Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold periods. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 37 BIOCLIMATIC ARCHITECTURAL DESIGN

kISII

Figure 52 Location of KISII county Climatic Zone UPLAND Latitude 00° 17’ N Longitude 34° 45’ E Altitude 1,700 m

Figure 53 View of Kisii level 5 hospital

Source: http://www.d-maps.com/ Source: http://webstaging.info/tropical/location.html

Figure 54 Location of Kisii town in Kisii county

GEOGRAPHY AND bioclimatic data annual temperature is 19.5 °C with the warmest month on average being February. The lowest temperature Kisii town is the headquarters of Kisii county – known as average occurs in July. Relative humidity averages at 70% the home to the best stone carvers in Kenya. It is located annually while the wind velocity ranges 2.2 – 4.2 m/s with at geographic coordinates of 0° 41’ S, 34° 46’ E and at an the predominant wind direction being East and East South altitude of 1,700 m above sea level, it enjoys an upland East (ESE). The annual average global solar radiation in this climate with rainfall recorded throughout the year at an town is 5.5 kWh/m2. average of 1,840 mm. The greatest amount occurs in April while the least amount is recorded in January. The average

table 8 KISII monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 20.4 61.0 2.6 5.7 4.6 2.5 89.7 FEB 20.4 66.8 2.6 5.9 4.9 2.3 104.6 MAR 20.3 70.8 2.2 5.7 4.4 2.5 172 APR 19.8 74.4 2.5 5.3 3.7 2.6 252.1 MAY 19.1 75.5 3.7 5.1 3.6 2.5 201.4 JUN 18.9 75.6 3.6 4.9 3.7 2.3 153.4 JUL 18.8 69.5 4.2 5.2 4.1 2.3 114.6 AUG 19.3 64.1 4.2 5.7 4.4 2.4 148.6 SEP 19.2 65.7 3.5 5.9 4.4 2.5 140.7 OCT 19.7 68.8 2.6 5.7 4.0 2.6 143.6 NOV 18.9 71.9 3.7 5.1 3.3 2.7 194.3 DEC 19.6 71.3 2.6 5.5 4.5 2.4 125.4

Figure 55 Monthly mean maximum and minimum temperature for KISII T-MiN T-MAX Kisii 40 35 30 26.4 25.7 25.4 24.7 23.7 24.8 24.7 23.5 25 23.1 23.2 23.2 22.8 C]

° 20 16.5 16.9 16.8 16.4 16.4 [ 15.5 15.9 15.4 15.6 15.5 15.9 16 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 56 Monthly mean relative humidity for KISII rH-MiN rH-MAX Kisii 100 84 84 85 79 81 80 80 79 81 75 77 80 71 62 62 61 58 60 55 55 53 54 46 49 41 43 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 39 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 57 monthly average rainfall for KISII

rAiNFALL Kisii 350 300 252.1 250 201.4 194.3 200 172 153.4 148.6 140.7 143.6 [mm] 150 125.4 104.6 114.6 89.7 100 50 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 58 Polar sun path diagram for Latitude 0° (Equator) 40 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 59 Wind rose diagram showing the prevailing wind direction in KISII

Figure 60 Psychrometric chart with passive design strategies overlays for KISII

Interpretation • Excessive glazing should be avoided as it can lead to overheating during the hot period as well as lead The hourly outdoor dry bulb temperatures and relative to extensive heat loss at night or during the cold humidity points, as seen in Figure 60, indicate that most of periods. the time the region is within the comfort zone band with a few hours beyond the comfort zone. During this period, • All windows should be airtight to prevent heat thermal mass is effective in extending the comfort zone losses when the outdoor temperatures are below by absorbing and storing daytime solar heat for release at the comfort zone and they should be located on night when the temperatures fall below the comfort zone. opposite walls to allow for cross-ventilation.

The psychrometric chart also shows that most of the • Additional heating systems such as fireplaces can be time the data points go below the comfort zone therefore incorporated in the design. indicating the need for heating. To extend the comfort zone during this period, passive heating through direct • Internal heat gains from occupants, equipment and solar heat gain and thermal mass are the most effective lights will greatly reduce heating needs. design strategies. Furthermore, internal heat gain from occupants, equipment and lights would contribute to a b. Protection against heat gain in the hot reduction in heating needs. period

• Buildings should be oriented with the main glazed Bioclimatic recommendations windows facing north and south for easier sun According to the climatic data for Kisii, the following control and to minimise overheating during the hot design strategies are recommended for: periods.

a. Enabling passive heating • Large windows should be avoided on the east and west facing façades. • Careful orientation of buildings with main rooms facing north east is appropriate to allow a certain • Appropriate sun shading devices should be amount of solar radiation to penetrate for passive incorporated to keep out the solar radiation and heating during the cold periods. glare during certain hours of the day during the hot periods. • The floor plan should be organised such that it allows the sun to penetrate daytime spaces during the cold periods.

• Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold periods.

• Medium weight walls, floors and ceilings are recommended to explore passive heating by storing heat accumulated during the day (avoiding overheating) to balance the night time low temperatures to keep them at comfort level. 42 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

kISUMU

Figure 61 Location of KISUMU COunty Climatic Zone GREAT LAKES Latitude 00° 06’ S Longitude 34° 45’ E Altitude 1,131 m

Figure 62 Aerial view of Kisumu city

Source: http://www.d-maps.com/ Source: http://www.africatravelresource.com/kisumu-town-safari/

Figure 63 Location of Kisumu town in Kisumu county

GEOGRAPHY AND bioclimatic data with the least amount. The average annual temperature is 22.9 °C with the warmest month on average being Kisumu city, the headquarters of Kisumu county, is February while the coolest month on average is July. the third largest city in Kenya. It is located at geographic Relative humidity averages at 69.4% annually while the coordinates 00° 06’ S, 34° 45’ E at an altitude of 1,131 m wind velocity ranges 2.2 – 3.7 m/s with the predominant above sea level. Its climate is characterised by rainfall being wind direction being East North East (ENE). The annual recorded throughout the year with an average amount of average global solar radiation in Kisumu is 5.7 kWh/m2. 1,350 mm. The month with the most amount of rainfall is April while July and August are recorded as the months table 9 KISUMU monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 23.8 61.0 3.5 5.9 5.2 2.3 90 FEB 24.0 64.0 3.7 6.2 5.3 2.3 100 MAR 23.2 71.0 3.5 6.0 4.6 2.5 170 APR 23.4 73.0 3.0 5.4 3.7 2.6 180 MAY 22.3 79.0 2.2 5.2 3.8 2.5 170 JUN 22.0 74.0 2.3 5.3 4.1 2.3 90 JUL 21.6 71.0 3.1 5.3 4.0 2.5 70 AUG 22.1 69.0 2.6 5.7 4.2 2.5 70 SEP 22.9 65.0 2.8 6.0 4.5 2.6 90 OCT 23.0 69.0 2.9 5.8 4.1 2.7 100 NOV 23.2 69.0 3.1 5.4 3.7 2.7 130 DEC 23.4 68.0 2.8 5.7 4.6 2.4 90

Figure 64 Monthly mean maximum and minimum temperature for KISUMU T-MiN T-MAX Kisumu 40 35 29.3 29.3 28.6 28.4 29.3 29 28.6 29.4 30 27.1 27.9 27 28.3 25 19 19.6 19 19.7 18.6 18.9 18.5 18.4 18.3 C] 17.2 17.5 18.1

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 65 Monthly mean relative humidity for KISUMU rH-MiN rH-MAX Kisumu 100 93 92 86 88 87 85 85 85 86 81 81 76 80 58 53 60 49 48 48 45 46 48 42 44 41 43 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 44 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 66 Monthly average rainfall for KISUMU

rAiNFALL Kisumu 350 300 250

200 170 180 170

[mm] 150 130 90 100 90 90 100 90 100 70 70 50 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 67 Polar sun path diagram for Latitude 0° (Equator) EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 45 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 68 Wind rose diagram showing the prevailing wind direction in KISUMU

Figure 69 Psychrometric chart with passive design strategies overlays for KISUMU

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 46 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • North and south facing walls should have large and fully openable openings. These openings The psychrometric chart (see Figure 69) shows that the should preferably be oriented to take advantage of Great Lake climate of Kisumu experiences some degree the prevailing breezes to facilitate natural airflow. of thermal comfort. It also shows that most of the hourly Openings at body level are more effective. data points of outdoor dry bulb temperature and relative humidity fall beyond the comfort zone thus experiencing • Openings should be located on opposite sides of high temperature and humidity. Certain periods of the walls to allow for proper cross-ventilations. Internal year have the outside conditions falling below the comfort walls should also have openings for airflow through zone. The chart therefore suggests that natural ventilation, the internal space. passive heating through direct solar heat gain and thermal mass are the most effective strategies for improving • It is advisable to have permanent vents / openings thermal comfort. close to the ceiling / roof to prevent the built up of hot air and encourage thermal air movement Bioclimatic recommendations (Figure 71). The design objectives and responses for Great Lakes • Ventilated double roofs enhance ventilation of the climate like Kisumu’s should be to address issues due to roof minimising overheating. high daily temperatures variation, high relative humidity and high solar radiation levels. The following passive design strategies may be used to address the cooling and heating requirements that result from the above climatic characteristics: Figure 70 Extensive use of horizontal and a. To provide maximum protection against Vertical shading devices direct and indirect solar radiation

• Buildings should be oriented with their long axis running east – west to provide effective shading.

• Openings should be located on the north and south facing façades and avoided on the east and west facing façades to reduce heat gain from the low early morning and late afternoon sun.

• Appropriate shading devices should be located on all openings. These can be in form of extended roof eaves, vertical fins, covered verandas and porches etc (Figure 70).

• Additional solar radiation protection may be provided by shade-providing vegetation within the space surrounding the building.

• Reflective roof surfaces and light coloured external finishes are appropriate to reflect solar radiation and minimise heat gains.

b. To promote maximum ventilation

• Building layout should be widely spaced to avoid obstruction of the wind and allow maximum ventilation around and inside buildings.

• Long and narrow buildings (shallow floor plans) Vasity Plaza, Kisumu © UN-Habitat / Jerusha NGUNGUI are more suited to this climate as they provide maximum airflow through them. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 47 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 71 Residential building showing horizontal shading devices protecting opening from the midday sun, high level ventilation blocks above windows to facilitate natural Ventilation and light coloured external finishes to reflect solar radiation

c. Enabling passive heating

• Medium weight walls, floors and ceilings are recommended to explore passive solar gains by storing heat accumulated during the day (avoiding overheating) to balance the night time low temperatures to keep them at comfort level.

• Excessive glazing should be avoided as it can lead to overheating during the hot period as well as lead to extensive heat loss at night or during the cold periods.

• All windows should be airtight to prevent heat losses when the outdoor temperatures are below the comfort zone. 48 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

kITALE

Figure 72 Location of TRANS NZOIA Climatic Zone UPLAND COunty Latitude 01° 01’ N Longitude 35° 00’ E Altitude 1,900 m

Figure 73 STREET VIEW OF KITALE TOWN

Source: http://www.d-maps.com/ Source: https://heartodarkness.wordpress.com/2006/11/01/the-road-to-loki1/

Figure 74 Location of KiTALE town in TRANS NZOIA county

GEOGRAPHY AND bioclimatic data rainfall averages 1,070 mm with the lowest amount occurring in January. Most rainfall occurs in May and Kitale, an agricultural town, is the headquarters of Trans- August. Relative humidity averages at 71.3% annually Nzoia county and is located at geographic coordinates of while the wind velocity ranges 1.7 – 3.0 m/s with the 1° 01’ N, 35° 00’ E at an altitude of 1,900 m above sea predominant wind direction being North East and East level. It enjoys a predominantly cool upland climate with North East (ENE). The annual average global solar radiation temperatures averaging at 18.1 °C annually. The period in Kitale is 5.4 kWh/m2. between July and September is the coolest, while February and March are the warmest months of the year. Annual table 10 KITALE monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 18.8 57.0 3.0 5.8 5.1 2.4 10 FEB 19.7 54.0 2.7 6.2 5.7 2.2 40 MAR 19.9 63.0 3.0 5.8 4.2 2.7 70 APR 18.8 73.0 2.2 5.2 3.2 2.7 130 MAY 18.3 77.0 1.8 5.2 3.7 2.6 160 JUN 17.2 82.0 1.7 4.9 3.4 2.5 110 JUL 16.9 81.0 2.0 4.9 3.0 2.7 140 AUG 16.9 82.0 2.4 5.2 3.4 2.8 160 SEP 16.9 76.0 1.9 5.6 4.1 2.6 100 OCT 17.9 74.0 2.1 5.6 3.7 2.8 80 NOV 18.0 75.0 2.2 5.3 3.5 2.8 50 DEC 18.4 62.0 2.8 5.6 4.7 2.5 20

Figure 75 Monthly mean maximum and minimum temperature for KITALE T-MiN T-MAX Kitale 40 35 30 25.3 25.8 25.9 23.8 23.9 23.6 24.7 25 22.7 22.3 21.4 21.6 22.6 C]

° 20 [ 14.5 13.8 14.4 15.1 14.1 15 12.3 13.2 13.1 13 13.2 13.2 12.5 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 76 Monthly mean relative humidity for KITALE rH-MiN rH-MAX Kitale 96 96 95 100 91 91 92 91 92 86 84 79 77 80 61 62 62 57 56 60 50 48 50

[%] 39 37 40 33 31

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 50 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 77 MONthly average rainfall for KITALE

rAiNFALL Kitale 350 300 250

200 160 160 140 [mm] 150 130 110 100 100 70 80 40 50 50 10 20 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 78 Polar sun path diagram for Latitude 1° NORTH EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 51 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 79 Wind rose diagram showing the prevailing wind direction in KITALE

Figure 80 Psychrometric chart with passive design strategies overlays for KITALE

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 52 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive heating by The psychrometric chart (see Figure 80) shows that storing heat accumulated during the day (avoiding Kitale is predominantly cool with outdoor conditions of overheating) to balance the night time low hourly dry bulb temperatures and relative humidity falling temperatures to keep them at comfort level. within as well as below the comfort zone. This indicates that heating is necessary during the under heated period. • Excessive glazing should be avoided as it can lead The chart therefore suggests that the most effective to overheating during the hot period as well as lead strategy for extending the thermal comfort zone would to extensive heat loss at night or during the cold be through passive heating through direct solar heat gain periods. and thermal mass. In addition, internal heat gain from occupants, equipment and lights would contribute to a • All windows should be airtight to prevent heat reduction in heating needs. losses when the outdoor temperatures are below the comfort zone and they should be located on However, during certain times of the year, the hourly opposite walls to allow for cross-ventilation. data points (outdoor dry bulb temperature and relative humidity) fall beyond the comfort zone. Thermal mass is • Additional heating systems such as fireplaces can be effective in extending the comfort zone by absorbing and incorporated in the design. storing daytime solar heat for release at night when the temperatures fall below the comfort zone. • Internal heat gains from occupants, equipment and lights will greatly reduce heating needs.

Bioclimatic recommendations b. Protection against heat gain in the hot According to the climatic data for Kitale, the following period design strategies are recommended for: • Buildings should be oriented with the main glazed a. Enabling passive heating windows facing north and south for easier sun control and to minimise overheating during the hot • Careful orientation of buildings with main rooms periods. facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive • Large windows should be avoided on the east and heating during the cold periods. west facing façades.

LAMU

Figure 81 Location of LAMU COunty Climatic Zone HOT AND HUMID Latitude 02° 16’ 6 Longitude 40° 54’ E Altitude 308 m

Figure 82 LAMU ISLAND SEAFRONT

Source: http://www.d-maps.com/ Source: https://commons.wikimedia.org/wiki/File:Lamu,_Lamu_Island,_Kenya. jpg#/media/File:Lamu,_Lamu_Island,_Kenya.jpg © Erik HERSMAN

Figure 83 Location of Lamu town in Lamu county

GEOGRAPHY AND bioclimatic data The average amount of rainfall recorded annually is 895 mm with the highest recorded amount in May and the Lamu town, the headquarters of Lamu county is one least amount in February. Wind velocity ranges 2.6 – 5.5 of the oldest inhabited towns in Kenya and is a UNESCO m/s with the predominant wind direction being East North World Heritage site. It is located at geographic coordinates East (December to March) and South (April to November). of 2° 16’ S, 40° 54’ E at an altitude of 308 m above The annual average global solar radiation in Lamu is 5.6 sea level. It enjoys a hot and humid climate with high kWh/m2. temperatures throughout the year (average of 27.1 °C) while the annual mean relative humidity is around 78.2%.

table 11 LAMU monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 27.6 77.0 4.6 6.1 5.0 2.4 7 FEB 28.0 76.0 3.4 6.4 5.5 2.4 3 MAR 28.6 76.0 3.2 6.2 4.8 2.5 32 APR 28.5 80.0 3.5 5.4 3.9 2.5 135 MAY 27.2 82.0 4.8 4.7 3.0 2.6 299 JUN 26.2 78.0 5.2 4.6 3.0 2.5 145 JUL 25.4 78.0 5.5 5.0 3.4 2.5 82 AUG 25.5 79.0 5.3 5.3 3.6 2.6 41 SEP 25.9 77.0 4.1 5.8 3.9 2.8 47 OCT 27.1 77.0 3.3 5.9 4.3 2.7 37 NOV 27.8 78.0 3.3 6.0 4.6 2.6 42 DEC 27.6 80.0 2.6 5.7 4.5 2.5 25

Figure 84 Monthly mean maximum and minimum temperature for LAMU T-MiN T-MAX lamu 40

35 30.8 31.5 31.1 30.5 30.3 29 29.5 30.2 27.4 28 30 26.5 26.9 25.9 26.7 27 25.8 25.6 25.3 24.5 24.4 24.6 25.2 25.7 25.2 25 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 85 Monthly mean relative humidity for LAMU rH-MiN rH-MAX lamu 100 90 85 85 86 87 87 85 88 80 80 83 82 80 74 73 73 73 69 67 69 64 64 62 65 65 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 55 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 86 Monthly average rainfall for LAMU

rAiNFALL lamu 350 299 300 250 200 135 145 [mm] 150 100 82 41 47 37 42 50 32 25 7 3 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 87 Polar sun path diagram for Latitude 2° SOUTH 56 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 88 Wind rose diagram showing the prevailing wind direction in LAMU

Figure 89 Psychrometric chart with passive design strategies overlays for LAMU

Interpretation a. To provide maximum protection against direct and indirect solar radiation The outdoor hourly dry bulb temperatures and relative humidity data points indicate that Lamu is completely out of • Buildings should be oriented with their long axis the comfort zone (see Figure 89). The resulting combination running east – west to provide effective shading. of high temperatures and high relative humidity causes discomfort in the region throughout the year. Thermal • Openings should be located on the north and south comfort can however be achieved passively through natural facing façades and avoided on the east and west ventilation for temperatures below 33 °C but beyond the facing façades to reduce heat gain from the low comfort zone. This makes it the most appropriate strategy early morning and late afternoon sun. to extend the comfort zone. However, Figure 90 indicates that artificial cooling using fans or air conditioners will be • Appropriate shading devices should be located on necessary for periods where temperatures are above 33 °C. all openings. These can be in form of extended roof eaves, covered verandas and porches etc.

Bioclimatic recommendations • Additional solar radiation protection may be The design objectives and responses for a hot and humid provided by shade-providing vegetation within the climate like Lamu’s should be to address issues due to space surrounding the building. high temperatures, high relative humidity and high solar radiation levels. The following passive design strategies • Reflective roof surfaces and light coloured external may be used to address the cooling requirements that finishes are appropriate to reflect solar radiation result from the above climatic characteristics: and reduce heat gains (Figure 90).

Figure 90 Lightly coloured exterior surfaces reflect unwanted solar radiation, while timber shutters encourage unrestricted air movement in and out of the building while at the same time cutting out direct sunlight into the indoor spaces thus minimising heat gain.

Swahili Dreams house, Lamu Source: http://urkosanchez.com/en/project/6/swahili-dreams.html © Corrie WINGATE, Urko Sánchez Architects 58 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

• Lightweight building materials with low thermal • Openings should be located on opposite sides of capacity are recommended for walls, floors and walls to allow for proper cross-ventilations. Internal roofs to allow rapid cooling at night. walls should also have openings for airflow through the internal space. b. To promote maximum ventilation • It is advisable to have permanent vents / openings • Building layout should be widely spaced to avoid close to the ceiling / roof to prevent the built up of obstruction of the wind and allow maximum hot air and encourage thermal air movement. ventilation around and inside buildings (Figure 91). • Ventilated double roofs enhance ventilation of the • Long and narrow buildings (shallow floor plans) roof minimising overheating are more suited to this climate as they provide maximum ventilation.

• North and south facing walls should have large and fully openable openings. These openings should preferably be oriented to take advantage of the prevailing breezes to facilitate natural airflow. Openings at body level are more effective.

Figure 91 Passive means of ventilation is provided by the provision of large openings that airflow across the living spaces therefore promoting cross ventilation for natural cooling.

The Red pepper house, Lamu Source: http://urkosanchez.com/en/project/11/the-red-pepper-house.html © Alberto HERAS, Steve MANN EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 59 BIOCLIMATIC ARCHITECTURAL DESIGN

LODWAR

Figure 92 Location of TURKANA Climatic Zone HOT ARID COunty Latitude 03° 07’ N Longitude 35° 36’ E Altitude 477 m

Figure 93 Aerial view of Lodwar town

Source: http://www.d-maps.com/ Source: https://turkanamih.wordpress.com

Figure 94 Location of Lodwar town in Turkana county

GEOGRAPHY AND bioclimatic data month recorded is March and the coolest month recorded is July. Relative humidity averages at 45% annually and Lodwar town, located on the west of Lake Turkana, can get to as low as 38% in February. Wind velocity ranges is the headquarters of Turkana county and is the largest 3.1 – 4.9 m/s with the predominant wind direction being town in the north-western Kenya. Its geographic location East and East North East (ENE). This town experiences is 03° 07’ N, 35° 36’ E at an altitude of 477 m above sea intense solar radiation throughout the year with an annual level. Being in a hot arid climate, the town experiences average global solar radiation of 6.1 kWh/m2. high temperatures (annual mean of 29.7 °C) and little rainfall with an annual average of 231 mm. The hottest

table 12 LODWAR monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 29.5 41.0 3.7 6.2 5.3 2.5 11.6 FEB 30.3 38.0 3.6 6.5 5.2 2.7 9.2 MAR 30.6 43.0 4.9 6.3 4.3 2.9 27.8 APR 30.1 53.0 4.6 5.9 4.0 2.8 57.1 MAY 30.1 50.0 3.3 5.8 4.3 2.7 29.8 JUN 29.4 48.0 3.9 5.9 5.0 2.3 9 JUL 28.5 45.0 4.6 6.0 5.3 2.3 21.3 AUG 29.1 46.0 3.5 6.3 5.7 2.2 10 SEP 29.9 43.0 4.2 6.7 6.4 2.0 6.2 OCT 29.8 47.0 4.0 6.2 5.1 2.5 10.6 NOV 29.9 46.0 4.3 5.8 4.6 2.6 24.4 DEC 29.6 44.0 3.1 5.9 5.1 2.4 14.6

Figure 95 Monthly mean maximum and minimum temperature for LODWAR T-MiN T-MAX lodWar 40 35.1 35.8 35.1 34.1 33.9 33.4 34.5 34.3 34.4 34.4 35 33.1 32.3

30 25.9 26 26.2 26.3 24.1 25.5 25 25 25.4 25.4 24.8 25 22.9 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 96 Monthly mean relative humidity for LODWAR rH-MiN rH-MAX lodWar 100

80 71 65 62 61 62 60 59 56 57 59 58 60 52

[%] 38 36 36 34 40 32 32 30 33 33 31 27 26 20

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 61 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 97 Monthly average rainfall for LODWAR

rAiNFALL lodWar 350 300 250 200

[mm] 150 100 57.1 50 27.8 29.8 21.3 24.4 11.6 9.2 9 10 6.2 10.6 14.6 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 98 Polar sun path diagram for Latitude 3° NORTH 62 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 99 Wind rose diagram showing the prevailing wind direction in LODWAR

Figure 100 Psychrometric chart with passive design strategies overlays for LODWAR

Interpretation • Use of vegetation is effective in improving the air quality by reducing the air temperature as Lodwar’s climate is predominantly hot throughout the year well as elevate the humidity level because of the with outside conditions (dry bulb temperature and relative evaporative cooling effect of plants. humidity) beyond the comfort zone Therefore, cooling is very important and buildings need much more cooling c. To balance diurnal temperature range and no heating at all. Based on the psychrometric chart (see Figure 100), the most appropriate cooling strategies to • Heavy weight building materials with high thermal extend the limit of comfort include the following: shading, capacity are recommended to balance temperature natural ventilation, high thermal mass with night ventilation variations between day and night. These heat (night flushing) and evaporative cooling. storing materials keep daytime temperatures down.

• Due to the heat absorption qualities of the ground, Bioclimatic recommendations earth-sheltered and underground housing are The following passive design strategies may be used to suited for this climate. address the cooling requirements of Lodwar’s climate: d. To ensure air circulation a. To reduce effects of intense solar radiation • Openings should be located to take advantage of • Compact layout of buildings is recommended to prevailing winds and allow for cross-ventilation. provide mutual shading and minimise exposure to solar radiation. • Ventilation through windows should be kept at a minimum during the daytime to keep hot and dusty • Courtyard design of buildings minimises the impact air out. This also minimised heat gains. However, at of solar radiation on the outer walls as well as night, windows may be opened to provide adequate provide cool spaces within the buildings / building ventilation for dissipation of heat accumulated layout. This increases the daytime cooled spaces. during the day by walls and the roof to prevent overheating of the interior space. • Buildings should be oriented along the east – west axis with the longer sides facing north and south to • Other ventilation strategies include use of wind prevent solar heat gains. The building’s surface area catchers, wind towers, solar chimneys, roof- exposed to the east and west should be minimised. mounted exhaust fans, high level vents etc.

• Openings should be located on the north and south e. To minimise problems associated with dust facing façades. Small openings that are located high on the walls are recommended to facilitate • Vegetation can be used to filter dust from the air natural ventilation as well as reduce glare from light before it gets into the building. reflected from the ground or surrounding buildings. • Closing windows during daytime prevents dust from • Appropriate shading devices are necessary on all getting into the building on windy days. Windows openings to minimise heat gain from solar radiation. should be tight-fitting as possible to prevent dust Use of vegetation, verandas, covered walkways, from infiltrating. pergolas etc. is recommended to provide shade to walls, openings and outdoor spaces.

• Use of reflective surfaces (roof) and light-coloured walls are effective in reflecting solar radiation thus minimising solar heat gains and consequently minimising internal daytime temperatures.

b. To counter low relative humidity

• Evaporative cooling is recommended in this climate to improve the microclimate by elevating the humidity level while at the same time cooling the surrounding air. The following strategies are recommended: fountains, spray ponds, water surfaces, moistened fabrics, sprinklers or porous pots etc. 64 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 101 Traditional hut showcasing use of natural and local materials. Main opening to the Hut is oriented away from the sun.

MAKINDU

Figure 102 Location of MAKUENI Climatic Zone HOT SEMI -ARID / SAVANNAH COunty Latitude 02° 16’ 6 Longitude 37° 49’ E Altitude 1,070 m

Figure 103 Main commercial street in Makindu town

Source: http://www.d-maps.com/ © UN-Habitat / Jerusha NGUNGUI

Figure 104 Location of Makindu town in Makueni county

GEOGRAPHY AND bioclimatic data recorded as the month with the most amount of rainfall at an average of 170 mm. Relative humidity averages at Makindu is a town located in Makueni county at 69.2% annually while the wind velocity averages at 2.6 geographic coordinates of 02° 16’ S, 37° 49’ E. At m/s with the predominant wind direction being East South an altitude of 1,070 m above sea level, the town has East (ESE) and South East. The annual average global solar savannah climate with high temperatures (annual mean radiation in Makindu is 5.5 kWh/m2. of 22.4 °C) and low amounts of rainfall (annual average of 690 mm). The warmest month on average is March while the coolest month on average is July. November is

table 13 MAKINDU monthly mean climatic data

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 22.4 77.0 2.2 5.8 4.3 2.8 40 FEB 23.9 63.0 2.5 6.0 4.5 2.7 30 MAR 24.9 67.0 2.9 6.0 4.4 2.7 80 APR 23.3 77.0 2.3 5.5 3.8 2.7 120 MAY 22.2 72.0 2.2 5.2 4.1 2.4 120 JUN 21.1 70.0 2.1 4.7 3.8 2.3 0 JUL 20.3 68.0 2.7 4.7 3.5 2.4 0 AUG 20.9 65.0 2.7 5.1 3.6 2.6 0 SEP 21.6 64.0 3.0 5.9 4.6 2.5 0 OCT 23.3 61.0 3.4 5.9 4.4 2.6 20 NOV 23.1 71.0 2.9 5.2 3.4 2.8 170 DEC 22.3 75.0 2.4 5.3 3.4 2.8 110

Figure 105 Monthly mean maximum and minimum temperature for MAKINDU T-MiN T-MAX maKindu 40 35 30.3 29.3 28.8 30 27.8 27.5 27.5 27.2 27.5 26.7 25.4 26 26.5 25 21.1 19.9 18.5 19.2 18.4 19.5 19.4 C] 17.8 17.2 ° 20 16.4 16.6 [ 15.6 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 106 Monthly mean relative humidity for MAKINDU rH-MiN rH-MAX maKindu 96 100 94 94 92 94 88 91 91 87 87 86 84 80

57 60 52 53 49 47 50 41 43 43 41 [%] 40 38 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 67 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 107 Monthly average rainfall for MAKINDU

rAiNFALL maKindu 350 300 250

200 170

[mm] 150 120 120 110 100 80 40 50 30 20 0 0 0 0 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 108 Polar sun path diagram for Latitude 2° SOUTH 68 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 109 Wind rose diagram showing the prevailing wind direction in MAKINDU

Figure 110 Psychrometric chart with passive design strategies overlays for MAKINDU

Interpretation • Appropriate shading devices are necessary on all openings to decrease heat gain from solar radiation. Makindu experiences both hot and cold conditions that Use of vegetation, verandas, covered walkways, fall above and below the comfort zone respectively as seen pergolas etc. is recommended to provide shade to in Figure 110. Based on the psychrometric chart, a combined walls, openings and outdoor spaces (Figure 111). effect of natural ventilation and thermal mass (along with night ventilation) are the most effective strategies to improve • Use of reflective surfaces (roof) and light coloured thermal comfort during the overheated period. In the case external walls are effective in reflecting solar radiation of the under heated period, passive heating through direct thus minimising solar heat gains and consequently solar heat gain and thermal mass are effective in expanding minimising internal daytime temperatures. the comfort zone when the temperatures fall below the comfort zone. b. To balance diurnal temperature range

• Medium weight building materials with high Bioclimatic recommendations thermal capacity are recommended to balance In Makindu, the design objective should be to balance temperature variations between day and night. the conflicting needs of the cold and hot periods to These materials absorb heat during daytime provide comfort. The following design strategies are keeping indoor temperatures lower than outdoor recommended: temperatures. The stored heat is later dissipated at night thereby providing indoor thermal comfort a. To reduce effects of intense solar radiation when the outdoor temperatures fall below the comfort zone. • Compact layout of buildings is recommended to provide mutual shading and minimise exposure to c. To ensure air circulation solar radiation. • Openings should be located to take advantage of • Courtyard design of buildings minimises the impact prevailing winds and allow for cross-ventilation. of solar radiation on the outer walls as well as provide cool spaces with the buildings / building • Ventilation through windows should be kept at a layout. minimum during the daytime to keep hot and dusty air out. However, at night, windows may be opened • Buildings should be oriented along the east – west to provide adequate ventilation for dissipation of axis with the longer sides facing north and south to heat accumulated during the day by walls and the prevent solar heat gains. The building’s surface area roof to prevent overheating of the interior space. exposed to the east and west should be minimised. • Other ventilation strategies include use of wind • Openings should be located on the north and south. catchers, wind towers, solar chimneys, roof- Small openings that are located high on the walls mounted exhaust fans etc. are recommended to facilitate natural ventilation as well as reduce glare from light reflected from the ground or surrounding buildings. 70 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 111 Extensive horizontal overhangs provide shade to the walls and openings below them thus minimising heat gain. Landscaping also provides cool shaded outdoor spaces.

Makindu Sikh Temple © Carmen MOLINA EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 71 BIOCLIMATIC ARCHITECTURAL DESIGN

MAlindi

Figure 112 Location of kilifi COunty Climatic Zone HOT AND HUMID Latitude 03° 13’ S Longitude 40° 07’ E Altitude 23 m

Figure 113 View of Malindi town

Source: http://www.d-maps.com/ Source: http://www.thegoldenscope.com/2014/04/malindi-where-to-go-for-an- authentic-experience/

Figure 114 Location of Malindi town in Kilifi county

GEOGRAPHY AND bioclimatic data of rainfall recorded annually is 578 mm with the highest recorded amount in April and the least amount in August. Malindi town, situated along the Indian Ocean coast of High wind velocity is recorded annually at an average of Kenya, is the largest urban centre in Kilifi county and is 4.6 m/s with the predominant wind direction being East located at geographic coordinates of 03° 13’ S, 40° 7’ E (December to March) and South (April to November). The and is elevated at 23 m above sea level. It enjoys a hot annual average global solar radiation in Malindi is 5.5 and humid climate with high temperatures throughout kWh/m2. the year (average of 26.4 °C) as well as high relative humidity (annual mean of 78.4%). The average amount

table 14 Malindi monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 27.4 77.0 4.2 6.1 4.5 2.8 29 FEB 27.6 75.0 5.6 6.3 4.8 2.7 14 MAR 28.1 76.0 4.3 6.2 4.3 2.8 68 APR 27.3 81.0 3.5 5.3 3.5 2.7 126 MAY 25.9 82.0 4.5 4.5 2.8 2.5 25 JUN 25.4 79.0 5.4 4.6 3.2 2.4 10 JUL 24.6 79.0 6.0 4.6 3.2 2.4 12 AUG 24.8 77.0 5.2 5.1 3.6 2.5 9 SEP 25.0 78.0 4.4 5.7 3.9 2.7 29 OCT 26.0 78.0 3.9 6.0 4.3 2.7 66 NOV 27.0 81.0 3.7 5.8 4.3 2.6 86 DEC 27.4 78.0 4.0 5.7 4.2 2.6 104

Figure 115 Monthly mean maximum and minimum temperature for Malindi T-MiN T-MAX malindi 40 35 30.1 30.9 30.8 29.9 29.7 28.4 29.1 30 27.3 27 26.6 26.6 27.3 25.5 25.9 25 25.1 24.9 24.4 24.2 23.5 24.4 25 22.9 22.8 23.1 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 116 Monthly mean relative humidity for Malindi rH-MiN rH-MAX malindi 100 91 88 91 88 86 87 87 84 86 85 86 87 77 80 71 73 70 69 67 70 67 65 63 66 59 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 73 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 117 Monthly average rainfall for Malindi

rAiNFALL malindi 350 300 250 200

[mm] 150 126 104 86 100 68 66 50 29 25 29 14 10 12 9 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 118 Polar sun path diagram for Latitude 3° South 74 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 119 Wind rose diagram showing the prevailing wind direction in Malindi

Figure 120 Psychrometric chart with passive design strategies overlays for Malindi

Interpretation • Appropriate shading devices should be located on all openings. These can be in form of extended roof Figure 120 shows that Malindi lies outside the comfort eaves, covered verandas and porches etc. (Figure 121). zone throughout the year. The resulting combination of high hourly outdoor dry bulb temperatures and relative • Additional solar radiation protection may be humidity causes discomfort. To improve thermal comfort, provided by shade-providing vegetation within the natural ventilation is the most appropriate strategy to adopt. space surrounding the building.

However, at certain times of the year, temperature go • Reflective roof surfaces and light coloured external above the natural ventilation zone and mechanical cooling finishes are appropriate to reflect solar radiation may be necessary to provide thermal comfort. and reduce heat gains (Figure 122).

• Lightweight building materials with low thermal Bioclimatic recommendations capacity are recommended for walls, floors and The design objectives and responses for a hot and humid roofs to allow rapid cooling at night. climate like Malindi’s should be to address issues due to high temperatures, high relative humidity and high solar b. To promote maximum ventilation radiation levels. The following passive design strategies may be used to address the cooling requirements that • Building layout should be widely spaced to avoid result from the above climatic characteristics: obstruction of the wind and allow maximum ventilation around and inside buildings. a. To provide maximum protection against direct and indirect solar radiation • Long and narrow buildings (shallow floor plans) are more suited to this climate as they provide • Buildings should be oriented with their long axis maximum ventilation. running east – west to provide effective shading. • North and south facing walls should have large • Openings should be located on the north and south and fully openable openings. These openings facing façades and avoided on the east and west should preferably be oriented to take advantage of facing façades to reduce heat gain from the low the prevailing breezes to facilitate natural airflow. early morning and late afternoon sun. Openings at body level are more effective.

Figure 121 Verandas and porches are a very effective means of providing shade. Vegetation absorbs solar radiation and not reflect it into the building.

Source: http://azizirealtors.co.ke/property/mijikenda-villas-malindi/ 76 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

• Openings should be located on opposite sides of walls to allow for proper cross-ventilations. Internal walls should also have openings for airflow through the internal space.

• It is advisable to have permanent vents / openings close to the ceiling / roof to prevent the built up of hot air and encourage thermal air movement.

• Ventilated double roofs enhance ventilation of the roof minimising overheating.

Figure 122 Lightly coloured external surfaces reflect unwanted solar radiation hence minimising heat gain

Neem House, Malindi © http://www.neemhousekenya.com/ EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 77 BIOCLIMATIC ARCHITECTURAL DESIGN

MANDERA

Figure 123 Location of Mandera Climatic Zone HOT ARID County Latitude 03° 55’ N Longitude 41° 50’ E Altitude 231 m

Figure 124 Aerial view of Mandera town

Source: http://www.d-maps.com/ Source: http://www.skyscrapercity.com/showthread.php?p=131709869

Figure 125 Location of Mandera town in Mandera county

GEOGRAPHY AND bioclimatic data an annual average of 273 mm with the highest amount received in April. Low relative humidity is experienced Mandera which is the headquarters of Mandera county, with an annual average of 51% while the wind velocity is located at geographic coordinates of 03° 55’ N, 41° 50’ averages ranges at 2.9 – 6.7 m/s with the predominant E at an altitude of 231 m above sea level. Its climate is wind direction being South. The annual average global categorized as hot arid with temperatures tending to be solar radiation in Mandera is 5.6 kWh/m2. high throughout the year with an annual average of 29.5 °C. The hottest month is recorded as March and the coolest month recorded as July. Rainfall is extremely low with

table 15 Malindi monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 30.4 45.0 3.4 6.4 6.5 2.0 1.4 FEB 30.9 38.0 4.9 6.8 6.8 2.0 5 MAR 31.5 46.0 4.1 6.4 5.1 2.6 17.7 APR 29.8 63.0 3.8 5.4 3.1 3.0 95.5 MAY 29.6 58.0 4.3 5.2 2.9 3.1 40.7 JUN 28.6 53.0 5.6 5.0 2.9 3.0 0.9 JUL 27.9 50.0 6.7 5.0 2.6 3.1 1.5 AUG 28.3 48.0 6.5 5.5 3.2 3.0 0.5 SEP 29.4 48.0 5.5 5.8 3.8 2.9 1.9 OCT 29.7 52.0 3.6 5.4 3.3 2.9 46.2 NOV 28.2 59.0 2.9 5.0 3.3 2.7 52 DEC 29.6 51.0 3.3 5.7 5.2 2.2 9.9

Figure 126 Monthly mean maximum and minimum temperature for Mandera T-MiN T-MAX mandera 40 35.3 35.8 36.2 34 33.7 33.8 34.3 34.3 35 32.2 31.5 32.6 32.5 30 25.5 25.7 26.3 26.3 25.8 25.4 24.8 24.2 23.8 24.7 24.7 24.5 25 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 127 Monthly mean relative humidity for Mandera rH-MiN rH-MAX mandera 100

79 77 80 74 66 68 68 63 64 64 62 63 56 60 45 42 41 42 [%] 38 36 35 38 36 40 31 32 26 20

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 79 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 128 Monthly average rainfall for Mandera

rAiNFALL mandera 350 300 250 200

[mm] 150 95.5 100 40.7 46.2 52 50 17.7 1.4 5 0.9 1.5 0.5 1.9 9.9 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 129 Polar sun path diagram for Latitude 3° North 80 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 130 Wind rose diagram showing the prevailing wind direction in Mandera

Figure 131 Psychrometric chart with passive design strategies overlays for Mandera

Interpretation b. To counter low relative humidity

Mandera’s climate is predominantly hot throughout the • Evaporative cooling is recommended in this year with outside conditions (dry bulb temperature and climate to improve the microclimate by elevating relative humidity) beyond the comfort zone (see Figure the humidity level while at the same time cooling 131). Therefore, cooling is very important and buildings the surrounding air. The following strategies are need much more cooling and no heating at all. Based on recommended: fountains, spray ponds, water the psychrometric chart, the most appropriate cooling surfaces, moistened fabrics, sprinklers or porous strategies to extend the limit of comfort include the pots etc. following: shading, natural ventilation, high thermal mass with night ventilation (night flushing) and evaporative • Use of vegetation is effective in improving the cooling. However, some days are too hot and dry for air quality by reducing the air temperature as the passive strategies to work successfully. Therefore, well as elevate the humidity level because of the convectional cooling and humidification may be necessary evaporative cooling effect of plants. during the overheated period to maintain thermal comfort when the passive cooling strategies cannot fulfil the cooling c. To balance diurnal temperature range demand. • Heavy weight building materials with high thermal capacity are recommended to balance temperature Bioclimatic recommendations variations between day and night. These heat The following passive design strategies may be used to storing materials keep daytime temperatures down. address the cooling requirements of Mandera’s climate: • As a result of heat absorption qualities of the a. To reduce effects of intense solar radiation ground, earth-sheltered and underground housing are suited for this climate. • Compact layout of buildings is recommended to provide mutual shading and minimise exposure to d. To ensure air circulation solar radiation. • Openings should be located to take advantage of • Courtyard design of buildings minimises the impact prevailing winds and allow for cross-ventilation. of solar radiation on the outer walls as well as provide cool spaces within the buildings / building • Ventilation through windows should be kept at a layout. This increases the daytime cooled spaces minimum during the daytime to keep hot and dusty (Figure 132). air out. This also minimised heat gains. However, at night, windows may be opened to provide adequate • Buildings should be oriented along the east – west ventilation for dissipation of heat accumulated axis with the longer sides facing north and south to during the day by walls and the roof to prevent prevent solar heat gains. The building’s surface area overheating of the interior space. exposed to the east and west should be minimised. • Other ventilation strategies include use of wind • Openings should be located on the north and south catchers, wind towers, solar chimneys, roof- facing façades. Small openings that are located mounted exhaust fans, high level vents etc. high on the walls are recommended to facilitate natural ventilation as well as reduce glare from light e. To minimise problems associated with dust reflected from the ground or surrounding buildings. • Vegetation can be used to filter dust from the air • Appropriate shading devices are necessary on all before it gets into the building. openings to decrease heat gain from solar radiation. Use of vegetation, verandas, covered walkways, • Closing windows during daytime prevents dust pergolas etc. is recommended to provide shade to from getting into the building on windy days. walls, openings and outdoor spaces. • Windows should be tight-fitting as possible to • Use of reflective surfaces (roof) and light-coloured prevent dust from infiltrating. walls are effective in reflecting solar radiation thus minimising solar heat gains and consequently minimising internal daytime temperatures. 82 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 132 High walls cut off the sun during the day hence providing shade to inner walls and Floor of the courtyard, preventing excessive heating. During the night, heat accumulated during the day is dissipated by re-radiation.

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 83 BIOCLIMATIC ARCHITECTURAL DESIGN

MERU

Figure 133 Location of MERU county Climatic Zone UPLAND Latitude 00° 03’ N Longitude 37° 39’ E Altitude 1,528 m

Figure 134 view of A STREET IN MERU town

Source: http://www.d-maps.com/ Source: © marete2010 https://www.flickr.com/photos/maasai1/6206978783/in/ photostream/

Figure 135 Location of MERU town in MERU County

GEOGRAPHY AND bioclimatic data high amount of rainfall throughout the year (annual average of 1,708 mm) with the wettest month on average Meru town, situated on the slopes of Mt. Kenya, is being April while the driest month being June. High the headquarters of Meru county and located on the relative humidity is recorded throughout the year with geographic coordinates of 00° 03’ N, 37° 39’ E. At an an annual average of 79%. This town experiences global altitude of 1,528 m above sea level, the town enjoys an solar radiation of 5.5 kWh/m2 with an annual average uplands climate with predominant cool temperatures of wind speed of 2.4 m/s blowing predominantly from South an annual average of 18.3 °C – the coolest and warmest East. months are July and March respectively. The town receives

table 16 MERU monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 18.1 80.0 2.1 5.9 5.3 2.3 57.5 FEB 18.2 76.0 2.3 6.5 5.9 2.3 56.7 MAR 19.7 77.0 2.4 6.1 5.0 2.5 117.3 APR 19.2 83.0 1.8 5.6 4.1 2.6 312.1 MAY 18.5 84.0 2.0 5.3 4.0 2.5 243.6 JUN 17.6 80.0 2.2 4.7 3.4 2.3 55.1 JUL 16.9 75.0 3.5 4.6 2.9 2.6 71.1 AUG 17.7 73.0 3.4 5.2 3.3 2.7 71 SEP 18.2 71.0 3.1 5.9 4.7 2.4 54.1 OCT 19.4 72.0 2.8 5.8 4.2 2.6 256.2 NOV 18.0 87.0 1.6 5.1 3.2 2.8 296.2 DEC 17.8 84.0 2.1 5.4 4.2 2.5 117.2

Figure 136 Monthly mean maximum and minimum temperature for MERU T-MiN T-MAX meru 40 35 30 23.7 24.1 23.7 23.7 24.9 25 23.4 22.5 22 22.1 22.3 21.2 20.3 C]

° 20 16.5 [ 15.3 15.5 13.9 13.6 14.5 14 14.4 13.5 14.6 14.8 13.9 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 137 Monthly mean relative humidity for MERU rH-MiN rH-MAX meru 100 94 95 93 92 93 95 94 90 88 88 88 89 74 80 71 70 65 68 65 61 61 62 57 60 49 50 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 85 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 138 Monthly average rainfall for MERU

rAiNFALL meru 350 312.1 296.2 300 243.6 256.2 250 200

[mm] 150 117.3 117.2 100 71.1 71 57.5 56.7 55.1 54.1 50 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 139 Polar sun path diagram for Latitude 0° (Equator) 86 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 140 Wind rose diagram showing the prevailing wind direction in MERU

Figure 141 Psychrometric chart with passive design strategies overlays for MERU

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive heating by The outdoor hourly outdoor dry bulb and relative storing heat accumulated during the day (avoiding humidity data points indicate that Meru falls within the overheating) to balance the night time low comfort zone during certain periods of the year (see Figure temperatures to keep them at comfort level. 141). However, for a substantial period of the year, the temperatures are clearly below comfort with temperatures • Excessive glazing should be avoided as it can lead getting to below 15 °C. Passive solar heating through to overheating during the hot period as well as lead direct solar gain heat and thermal mass is therefore the to extensive heat loss at night or during the cold most essential strategy for extending the thermal comfort periods. zone during this under heated period. In addition, internal heat gain from equipment, lights and occupants provide a • All windows should be airtight to prevent heat valuable source of heat contribution to space heating. losses when the outdoor temperatures are below the comfort zone and they should be located on Bioclimatic recommendations opposite walls to allow for cross-ventilation. The main design objective in Meru should be to increase • Additional heating systems such as fireplaces can be indoor temperature and maximise thermal comfort incorporated in the design. during the prevalent under heated period. According to the climatic data for Meru, the following design • Internal heat gains from occupants, equipment and strategies are recommended for: lights will greatly reduce heating needs.

a. Enabling passive heating b. Protection against heat gain in the hot period • Careful orientation of buildings with main rooms facing north east is appropriate to allow a certain • Buildings should be oriented with the main glazed amount of solar radiation to penetrate for passive windows facing north and south for easier sun heating during the cold periods (Figure 142). control and to minimise overheating during the hot periods. • The floor plan should be organised such that it allows the sun to penetrate daytime spaces during • Large windows should be avoided on the east and the cold periods. west facing façades.

• Compact forms reduce heat gains during the hot • Appropriate sun shading devices should be periods and minimise heat losses during the cold incorporated to keep out the solar radiation and periods. glare during certain hours of the day during the hot periods.

Figure 142 Solar access can be provided during the cold season for passive heating

Source: UN-Habitat (2015) Sustainable Building Design for Tropical Climates: Principles and Applications for Eastern Africa. Nairobi, Kenya: UN-Habitat. 88 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

MOMBASA

Figure 143 Location of Mombasa Climatic Zone HOT AND HUMID county Latitude 04° 03’ S Longitude 39° 40’ E Altitude 50 m

Figure 144 View of Mombasa tusks along Moi avenue

Source: http://www.d-maps.com/ Source: http://nomad.sleepout.com/wp-content/uploads/2014/12/mombasa1.jpg

Figure 145 Location of Mombasa town in Mombasa county

GEOGRAPHY AND bioclimatic data March while the coolest month is July. This city experiences intense solar radiation throughout the year with an annual Mombasa, the headquarters of Mombasa county, is the average global solar radiation of 5.4 kWh/m2. With an second largest city in Kenya after Nairobi. At a geographic annual average speed of 3.5 m/s, the predominant wind location of 04° 03’ S 39° 40’ E and an altitude of 50 m direction is East (December to March) and South (April to above sea level, the town’s climates is characterised by November). permanent high humidity (annual average of 80%) and high temperatures (annual average of 25.9 °C) with minimum daily temperature swings. The hottest month is table 17 Mombasa monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 26.8 78.0 3.6 5.8 3.8 3.0 20 FEB 27.0 75.0 3.9 6.0 4.1 2.9 10 MAR 28.1 77.0 3.0 6.0 4.1 2.8 60 APR 26.9 82.0 3.2 5.3 3.4 2.8 180 MAY 26.0 82.0 4.2 4.5 2.8 2.5 270 JUN 24.9 80.0 4.3 4.7 3.4 2.4 100 JUL 23.7 84.0 3.4 4.6 3.4 2.3 80 AUG 24.1 82.0 3.6 5.1 3.8 2.5 60 SEP 24.6 82.0 4.0 5.7 4.2 2.5 60 OCT 25.7 79.0 3.0 5.9 4.1 2.8 90 NOV 26.2 81.0 2.7 5.8 4.2 2.7 90 DEC 26.9 80.0 3.1 5.5 3.5 2.9 60

Figure 146 Monthly mean maximum and minimum temperature for Mombasa T-MiN T-MAX mombasa moi inti 40 35 31.6 30 30.6 29.6 28.5 28.4 29.7 29.7 30 27.8 26.6 26.8 27.3 25.3 24.8 24.4 24.3 24.1 23.3 23.4 24.5 25 22.4 21.3 21.7 22.5 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 147 Monthly mean relative humidity for Mombasa rH-MiN rH-MAX mombasa moi inti 93 95 93 93 93 100 90 89 91 90 92 90 91

80 71 67 67 67 67 63 65 66 65 66 57 59 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 90 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 148 Monthly average rainfall for Mombasa

rAiNFALL mombasa moi inti 350

300 270 250 200 180

[mm] 150 100 80 90 90 100 60 60 60 60 50 20 10 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 149 Polar sun path diagram for Latitude 4° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 91 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 150 Wind rose diagram showing the prevailing wind direction in Mombasa

Figure 151 Psychrometric chart with passive design strategies overlays for Mombasa

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 92 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation Figure 152 Proper orientation of buildings along the east west axis and minimal Figure 151 shows that Mombasa has its comfort region openings on the west facing façade. defined between 20 – 26 °C. The hourly outdoor dry bulb slanted glazed surfaces and provision temperatures and relative humidity points indicate that the of sun shading devices minimise heat region is of the comfort zone. The resulting combination gain. of high temperatures and high relative humidity caused discomfort. Thermal comfort can however be achieved passively through natural ventilation for temperatures below 33 °C but beyond the comfort zone. This makes it the most appropriate strategy to extend the comfort zone. However, at certain periods, outdoor dry bulb temperature and relative humidity fall outside the limits of natural ventilation, thereby necessitating the use of mechanical cooling and dehumidification to improve thermal comfort.

Bioclimatic recommendations According to the cooling needs required by a hot and humid climate like Mombasa’s, the following passive design strategies may be used:

a. To provide maximum protection against direct and indirect solar radiation

• Buildings should be oriented with their long axis running east – west to provide effective shading (Figure 152).

• Openings should be located on the north and south facing façades and avoided on the east and west Bank of India, Mombasa © UN-Habitat / Jerusha NGUNGUI facing façades to reduce heat gain from the low early morning and late afternoon sun. Figure 153 Example of a ventilated roof • Appropriate shading devices should be located on all openings. These can be in form of extended roof eaves, covered verandas and porches etc.

• Additional solar radiation protection may be provided by shade-providing vegetation within the space surrounding the building.

• Reflective roof surfaces and light coloured external finishes are appropriate to reflect solar radiation and reduce heat gains.

• Lightweight building materials with low thermal capacity are recommended for walls, floors and roofs to allow rapid cooling at night.

b. To promote maximum ventilation

• Building layout should be widely spaced to avoid obstruction of the wind and allow maximum ventilation around and inside buildings.

• Long and narrow buildings (shallow floor plans) are more suited to this climate as they provide © UN-Habitat / Jerusha NGUNGUI maximum ventilation. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 93 BIOCLIMATIC ARCHITECTURAL DESIGN

• North and south facing walls should have large • It is advisable to have permanent vents / openings and fully openable openings. These openings close to the ceiling / roof to prevent the built up of should preferably be oriented to take advantage of hot air and encourage thermal air movement. the prevailing breezes to facilitate natural airflow. Openings at body level are more effective. • Ventilated double roofs enhance ventilation of the roof minimising overheating (Figure 153). • Openings should be located on opposite sides of walls to allow for proper cross-ventilations. Internal walls should also have openings for airflow through the internal space.

Figure 154 Use of timber screens for shading the west facing openings against the later afternoon sun

A typical vernacular Swahili building (the Old Post office building) in Old Town, Mombasa © UN-Habitat / Jerusha NGUNGUI 94 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 155 Presence of permanent openings along walls enables airflow through the building. Vegetation provides shading. Lightly coloured external surface to reflect unwanted solar radiation.

Technical University of Mombasa © UN-Habitat / Jerusha NGUNGUI EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 95 BIOCLIMATIC ARCHITECTURAL DESIGN

MOYALE

Figure 156 Location of marsabit Climatic Zone HOT SEMI-ARID / SAVANNAH county Latitude 03° 31’ N Longitude 39° 3’ E Altitude 850 m

Figure 157 Aerial view of Moyale town

Source: http://www.d-maps.com/ Source: http://mobile.nation.co.ke/

Figure 158 Location of Moyale town in MARSABIT county

GEOGRAPHY AND bioclimatic data 714 mm of rainfall is recorded with the highest amount received in April while the lowest amount is recorded in Moyale town, located in Marsabit county, is a border August. The annual average global solar radiation in this town split between Kenya and Ethiopia. Its geographic town is 5.0 kWh/m2. The predominant wind direction is location is 03° 31’ N, 39° 3’ E and at an altitude of 850 South South East (SSE) at an annual mean velocity of 3.3 m above sea level. Its climate is characterized by high m/s. temperatures throughout the year – annual mean of 22.4 °C with February being the hottest month and July being the coolest month on average. An annual average of

table 18 MoYALE monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 24.8 44.0 4.2 6.0 5.8 2.1 17.2 FEB 25.8 48.0 3.4 6.3 5.8 2.3 19.6 MAR 24.5 61.0 3.5 5.6 4.0 2.7 55.3 APR 21.8 82.0 3.3 4.7 2.5 2.9 194.8 MAY 21.7 80.0 2.1 4.5 2.5 2.8 132.6 JUN 20.2 78.0 2.9 4.2 2.2 2.7 15.9 JUL 20.1 70.0 3.7 4.2 1.9 2.9 13.5 AUG 20.8 66.0 3.5 4.7 2.6 2.8 11.9 SEP 21.5 63.0 4.0 5.1 3.3 2.7 17.7 OCT 21.8 71.0 3.0 4.8 2.6 2.9 114.1 NOV 21.7 78.0 2.8 4.9 3.0 2.9 86.8 DEC 23.6 57.0 2.9 5.4 4.5 2.4 34.9

Figure 159 Monthly mean maximum and minimum temperature for Moyale T-MiN T-MAX moyale loWer 40 35 30.7 29.6 29.1 30 28.4 24.8 25 24.5 25.4 25.6 24.8 25 23.1 23.1 20.3 21.2 20.2 19.2 19.1 18.5 19.2 19.3 19.4 C] 18 17.4 17.5 ° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 160 Monthly mean relative humidity for Moyale rH-MiN rH-MAX moyale loWer 93 100 92 90 89 83 81 82 78 77 76 80 69 66 65 65 61 58 57 57 60 51 49 45

[%] 40 34 40 30

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 97 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 161 Monthly average rainfall for Moyale

rAiNFALL moyale loWer 350

300

250 194.8 200

[mm] 132.6 150 114.1 86.8 100 55.3 50 34.9 17.2 19.6 15.9 13.5 11.9 17.7 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 162 Polar sun path diagram for Latitude 3° North 98 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 163 Wind rose diagram showing the prevailing wind direction in Moyale

Figure 164 Psychrometric chart with passive design strategies overlays for Moyale

Interpretation b. To balance diurnal temperature range

Most of the outdoor hourly dry bulb temperature and • Medium weight building materials with high thermal relative humidity data point fall within the comfort zone. capacity are recommended to balance temperature However, the area experiences under heated periods variations between day and night. These materials with temperatures falling below the comfort zone to absorb heat during daytime keeping indoor 15 °C as well as overheated periods with temperatures temperatures lower than outdoor temperature. rising to 32 °C. Based on the psychrometric chart (see The stored heat is later dissipated at night thereby Figure 164), a combined effect of natural ventilation and providing indoor thermal comfort when the outdoor thermal mass (along with night ventilation) are the most temperatures fall below the comfort zone. effective strategies to improve thermal comfort during the overheated period. In the case of the under heated period, c. To ensure air circulation passive heating through direct solar heat gain and thermal mass are effective in expanding the comfort zone when • Openings should be located to take advantage of the temperatures fall below the comfort zone. prevailing winds and allow for cross-ventilation.

• Ventilation through windows should be kept at a Bioclimatic recommendations minimum during the daytime to keep hot and dusty In Moyale, the design objective should be to balance air out. However, at night, windows may be opened the conflicting needs of the cold and hot periods to to provide adequate ventilation for dissipation of provide comfort. The following design strategies are heat accumulated during the day by walls and the recommended: roof to prevent overheating of the interior space.

a. To reduce effects of intense solar radiation • Other ventilation strategies include use of wind catchers, wind towers, solar chimneys, roof- • Compact layout of buildings is recommended to mounted exhaust fans etc. provide mutual shading and minimise exposure to solar radiation. d. To minimise problems associated with dust

• Courtyard design of buildings minimises the impact • Vegetation can be used to filter dust from the air of solar radiation on the outer walls as well as before it gets into the building. provide cool spaces with the buildings / building layout. • Closing windows during daytime prevents dust from getting into the building on windy days. Windows • Buildings should be oriented along the east – west should be tight-fitting as possible to prevent dust axis with the longer sides facing north and south to from infiltrating. prevent solar heat gains. The building’s surface area Figure 165 Cantilevered construction, exposed to the east and west should be minimised. arcades, loggias and • Openings should be located on the north and south. High building parts provide Small openings that are located high on the walls mutual shading of buildings as are recommended to facilitate natural ventilation as Well as shaded outdoor spaces. well as reduce glare from light reflected from the ground or surrounding buildings.

• Appropriate shading devices are necessary on all openings to decrease heat gain from solar radiation. Use of vegetation, verandas, covered walkways, pergolas etc. is recommended to provide shade to walls, openings and outdoor spaces (Figure 165).

• Use of reflective surfaces (roof) and light-coloured walls are effective in reflecting solar radiation thus minimising solar heat gains and consequently minimising internal daytime temperatures.

Source: Gut, P. & Ackerknecht, D. (1993) Climate Responsive Building: Appropriate Building Construction in Tropical and Subtropical Regions. St. Gallen, Switzerland: SKAT, Switzerland. 100 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

NAIROBI

Figure 166 Location of NAIROBI Climatic Zone UPLAND county Latitude 01° 17’ S Longitude 36° 49’ E Altitude 1,661 m

Figure 167 Nairobi skyline

Source: http://www.d-maps.com/ Source: http://www.panoramio.com/photo/31634398 © Klaus MERCKENS

Figure 168 Location of Nairobi city in Nairobi county

GEOGRAPHY AND bioclimatic data in April / May and November / December. Relative humidity is above 60% throughout the year while the wind velocity Nairobi was founded in 1899 and is the political and ranges 0.9 – 2.9 m/s with the predominant wind direction capital city of Kenya. Located at geographic coordinates being East North East (ENE) and East. The annual average 01° 17’ S 36° 49’ E and at an altitude of 1,661 m above sea global solar radiation in Nairobi is 5.1 kWh/m2. level, the city enjoys an upland climate with annual average temperature of 18.8 °C. The hottest and coolest months are March and July respectively. The average annual rainfall is recorded at 710 mm with the highest amount occurring table 19 Nairobi (Dagoretti) monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 18.8 71.0 2.4 6.0 4.9 2.5 40 FEB 19.5 62.0 2.4 6.6 5.7 2.4 40 MAR 20.0 68.0 2.8 5.8 3.9 2.8 70 APR 18.7 79.0 1.9 4.9 2.8 2.8 160 MAY 17.7 81.0 1.3 4.3 2.4 2.6 110 JUN 16.7 81.0 0.9 4.1 2.4 2.4 30 JUL 15.7 80.0 0.9 4.0 2.2 2.5 10 AUG 16.3 73.0 1.1 4.7 3.0 2.5 10 SEP 17.5 68.0 1.6 5.3 3.5 2.6 20 OCT 18.2 71.0 2.5 5.2 3.2 2.8 40 NOV 17.7 81.0 2.3 4.7 2.6 2.8 110 DEC 17.7 79.0 2.9 5.4 3.9 2.5 70

Figure 169 Monthly mean maximum and minimum temperature for Nairobi – Dagoretti T-MiN T-MAX nairobi dagoretti 40 35 30 25.4 25.1 24.3 23.3 23.4 23.3 25 21.3 21.5 22.3 21.2 20.7 19.8 C]

° 20 [ 16.2 15.7 15.2 14.4 13.8 14.4 15.1 14.5 15 13.4 12.1 12.1 13.4 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 170 Monthly mean relative humidity for Nairobi - Dagoretti rH-MiN rH-MAX nairobi dagoretti 100 92 94 93 93 94 93 92 94 94 86 87 89 80 63 63 61 61 57 60 55 49 47 46 44 44 43 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 102 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 171 Monthly average rainfall for Nairobi

rAiNFALL nairobi 350 300 250

200 160

[mm] 150 110 110 100 70 70 40 40 30 40 50 10 10 20 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 172 Polar sun path diagram for Latitude 1° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 103 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 173 Wind rose diagram showing the prevailing wind direction in Nairobi

Figure 174 Psychrometric chart with passive design strategies overlays for Nairobi

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 104 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation Figure 175 The building is oriented with the long sides facing North – South and In Nairobi, most of the hourly points of outdoor dry the short sides facing East-West. bulb temperature and relative humidity fall within the oPenings are placed Along the North – comfort zone. However, a substantial portion falls below south facing façades. the comfort zone as seen in Figure 174. This means that during that period, space heating is necessary to extend the limit of comfort zone. This can be done through passive heating through direct solar heat gain and thermal mass. Further, internal heat gain from equipment, lights and occupants are also helpful in extending the thermal comfort and reducing heading heating demand.

Bioclimatic recommendations According to the climatic data for Nairobi, the following design strategies are recommended for:

a. Protection against heat gain in the hot period

• Buildings should be oriented with the main glazed windows facing north and south for easier sun control and to minimise overheating during the hot periods (Figure 175).

• Large windows should be avoided on the east and ICEA Building, Nairobi west facing façades. Source: http://www.jkuat.ac.ke/

• Appropriate sun shading devices should be Figure 176 Extensive use of horizontal and incorporated to keep out the solar radiation and glare during certain hours of the day during the hot Vertical shading devices all around periods (Figure 176). the building protects windows from direct solar penetration b. Enabling passive heating

• Careful orientation of buildings with main rooms facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive heating during the cold periods.

• The floor plan should be organised such that it allows the sun to penetrate daytime spaces during the cold periods.

• Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold periods.

• Excessive glazing should be avoided as it can lead to overheating during the hot period as well as lead to Kenindia House, Nairobi extensive heat loss at night or during the cold periods. Source:http://bauzeitgeist.blogspot.co.ke/2013/08/hauptstadt-von- ostafrika.html © MM Jones EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 105 BIOCLIMATIC ARCHITECTURAL DESIGN

• All windows should be airtight to prevent heat • Internal heat gains from occupants, equipment and losses when the outdoor temperatures are below lights will greatly reduce heating needs. the comfort zone and they should be located on opposite walls to allow for cross-ventilation.

• Additional heating systems such as fireplaces can be incorporated in the design.

Figure 177 All windows in the main façade are oriented facing North. They are deeply recessed to prevent direct solar radiation and glare. Horizontal aluminium light shelves reflect solar radiation while reflecting light into the interior spaces

Coca cola building, Nairobi © UN-Habitat / Jerusha NGUNGUI 106 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 178 The west facing façade is shaded using well designed sun shading elements that couple as aesthetic elements ensuring naturally lit spaces excluding solar heat gain

Administration Block, University of Nairobi Source: http://www.archidatum.com/projects/administration-block-university-of-nairobi/ © Karanja SAMUEL EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 107 BIOCLIMATIC ARCHITECTURAL DESIGN

NAKURU

Figure 179 Location of NAKURU Climatic Zone UPLAND county Latitude 00° 18’ S Longitude 36° 04’ E Altitude 1,850 m

Figure 180 Aerial view of Nakuru town

Source: http://www.d-maps.com/ Source: https://www.flickr.com

Figure 181 Location of Nakuru town in Nakuru county

GEOGRAPHY AND bioclimatic data town receives over 1,120 mm of annual rainfall with the highest amount received in August and the least amount Nakuru town, the headquarters of Nakuru county, is in January and February. Relative humidity is above 50% the fourth largest urban centre in Kenya and is located throughout the year while the wind velocity ranges 0.9 – at geographic coordinates of 0° 18’ S 36° 4’ E. At an 2.5 m/s with the predominant wind direction being North elevation of 1,850 m above sea level, the town enjoys an (October to April) and South East (May to September). upland climate characterised by cool temperatures (annual The annual average global solar radiation in Nakuru is 5.5 average of 17.8 °C) with the coolest month being July kWh/m2. while the warmest month on average being February. The

table 20 NAKURU monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 19.3 56.0 2.3 5.8 5.2 2.3 20 FEB 20.2 55.0 2.5 6.3 5.5 2.4 20 MAR 18.9 61.0 2.2 6.0 4.5 2.7 60 APR 18.1 75.0 1.7 5.2 3.3 2.8 180 MAY 17.9 75.0 1.8 5.2 3.7 2.6 140 JUN 17.1 73.0 1.3 5.0 3.8 2.4 120 JUL 15.9 75.0 1.6 5.1 3.6 2.5 150 AUG 17.0 72.0 1.7 5.4 3.7 2.7 190 SEP 17.1 71.0 1.9 5.8 4.2 2.6 100 OCT 17.3 73.0 1.2 5.6 3.8 2.7 50 NOV 17.2 75.0 0.9 4.9 2.9 2.8 50 DEC 17.9 67.0 2.0 5.6 4.6 2.5 40

Figure 182 Monthly mean maximum and minimum temperature for Nakuru T-MiN T-MAX naKuru 40 35 30 26.4 27.6 26.3 24.7 23.6 23.7 24.2 25 23 22.9 22.3 23 22.5 C]

° 20 [ 12.9 13.4 14.1 13.3 12.8 12.8 15 12.1 12.6 11.3 11.8 12.4 12.2 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 183 Monthly mean relative humidity for Nakuru rH-MiN rH-MAX naKuru 100 90 92 93 93 89 86 88 89 88 83 82 84 80

60 53 51 53 47 50 49 47 44 41 [%] 40 34 31 28

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 109 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 184 Monthly average rainfall for Nakuru

rAiNFALL naKuru 350 300 250 190 200 180 140 150 [mm] 150 120 100 100 60 50 50 40 50 20 20 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 185 Polar sun path diagram for Latitude 0° (Equator) 110 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 186 Wind rose diagram showing the prevailing wind direction in Nakuru

Figure 187 Psychrometric chart with passive design strategies overlays for Nakuru

Interpretation Bioclimatic recommendations

The psychrometric chart (see Figure 187) shows that According to the climatic data for Nakuru, the following Nakuru is predominantly cool with outdoor conditions design strategies are recommended for: of hourly dry bulb temperatures and relative humidity falling within as well as below the comfort zone. Outdoor a. Enabling passive heating temperatures can go below 10 °C. This indicates that heating is necessary during the under heated period. The • Careful orientation of buildings with main rooms chart therefore suggests that the most effective strategy facing north east is appropriate to allow a certain for extending the thermal comfort zone would be through amount of solar radiation to penetrate for passive passive heating through direct solar heat gain and thermal heating during the cold periods. mass. In addition, internal heat gain from occupants, equipment and lights would contribute to a reduction in • The floor plan should be organised such that it heating needs. allows the sun to penetrate daytime spaces during the cold periods. However, during certain times of the year, the hourly data points (outdoor dry bulb temperature and relative • Compact forms reduce heat gains during the hot humidity) fall beyond the comfort zone. Thermal mass is periods and minimise heat losses during the cold effective in extending the comfort zone by absorbing and periods. storing daytime solar heat for release at night when the temperatures fall below the comfort zone. • Medium weight walls, floors and ceilings are recommended to explore passive heating by storing heat accumulated during the day (avoiding overheating) to balance the night time low temperatures to keep them at comfort level.

Figure 188 South west facing elevation has louvered timber openings that can be closed off during the afternoon thus minimising unwanted heat gain during the hot afternoons

St. Jerome’s Centre, Nakuru Source: https://orkidstudio.co.uk/ © Odysseas MOURTZOUCHOS 112 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

• Excessive glazing should be avoided as it can lead b. Protection against heat gain in the hot to overheating during the hot period as well as lead period to extensive heat loss at night or during the cold periods. • Buildings should be oriented with the main glazed windows facing north and south for easier sun • All windows should be airtight to prevent heat control and to minimise overheating during the hot losses when the outdoor temperatures are below periods. the comfort zone and they should be located on opposite walls to allow for cross-ventilation. • Large windows should be avoided on the east and west facing façades. • Additional heating systems such as fireplaces can be incorporated in the design. • Appropriate sun shading devices should be incorporated to keep out the solar radiation and • Internal heat gains from occupants, equipment and glare during certain hours of the day during the hot lights will greatly reduce heating needs. periods.

Figure 189 Earth bags, made from grain bags filled large quantities of soil (20% clay content) are laid like oversized bricks to create deep high thermal mass walls. These walls are effective in absorbing heat from the sun, thus helping regulate temperatures during the cool nights.

St. Jerome’s Centre, Nakuru Source: https://orkidstudio.co.uk/ © Odysseas MOURTZOUCHOS EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 113 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 190 Louvered timber openings enable airflow thus encouraging natural ventilation

St. Jerome’s Centre, Nakuru Source: https://orkidstudio.co.uk/ © Odysseas MOURTZOUCHOS 114 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

NAROK

Figure 191 Location of Narok county Climatic Zone UPLAND Latitude 01° 05’ N Longitude 35° 52’ E Altitude 1,827 m

Figure 192 View of Narok town

Source: http://www.d-maps.com/ Source: http://www.mediamaxnetwork.co.ke/wp-content/uploads/2016/10/narok- town.jpg © Mayian Digital {James}

Figure 193 Location of Narok town in Narok county

GEOGRAPHY AND bioclimatic data April while the driest being July. Relative humidity is above 64% throughout the year while the wind velocity ranges Narok town, which is the headquarters of Narok 2.6 – 4.9 m/s with the predominant wind direction being county, is located at geographic coordinates of 01° 05’ North (October to March) and East / South East (April to S 35° 52’ E at an elevation of 1,827 m above sea level. September). The annual average global solar radiation in Its climate is categorised as upland with average annual Narok is 5.3 kWh/m2. temperatures of 17.3 °C. The hottest month on average is March and the coolest month recorded is July. Rainfall in Narok averages 770 mm with the wettest month being table 21 NAROK monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 17.8 72.0 2.4 5.6 4.8 2.3 74.6 FEB 18.3 67.0 3.7 6.1 5.1 2.4 69.1 MAR 18.4 67.0 4.0 5.9 4.5 2.5 90.6 APR 17.8 80.0 3.1 5.0 2.9 2.9 149.9 MAY 17.4 80.0 3.4 4.7 3.0 2.6 95.9 JUN 15.7 80.0 2.7 4.5 2.9 2.5 35.1 JUL 15.6 76.0 3.0 4.8 3.3 2.5 24.7 AUG 15.9 71.0 3.8 5.3 3.7 2.6 28.7 SEP 16.7 68.0 3.5 5.6 3.9 2.6 29.2 OCT 18.3 64.0 4.9 5.6 3.8 2.8 30.6 NOV 17.5 70.0 4.4 5.1 3.5 2.7 66.8 DEC 17.9 67.0 2.6 5.5 4.5 2.5 75.7

Figure 194 Monthly mean maximum and minimum temperature for Narok T-MiN T-MAX naroK 40 35 30 25.5 24.6 24.4 25 24.2 23.1 22.8 23.6 25 22 20.8 20.7 21.5 C]

° 20 [ 14.1 14.2 15 12.1 12.2 11.9 11.2 11.8 11.7 10.5 10.4 11.8 10.8 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 195 Monthly mean relative humidity for Narok rH-MiN rH-MAX naroK 100 93 94 94 94 92 91 87 89 90 90 87 89 80

56 58 59 60 54 47 48 46 47 43 42 [%] 40 39 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 116 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 196 Monthly average rainfall for Narok

rAiNFALL naroK 350 300 250 200 149.9

[mm] 150 90.6 95.9 100 74.6 69.1 66.8 75.7 50 35.1 24.7 28.7 29.2 30.6 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 197 Polar sun path diagram for Latitude 1° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 117 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 198 Wind rose diagram showing the prevailing wind direction in Narok

Figure 199 Psychrometric chart with passive design strategies overlays for Narok

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 118 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Medium weight walls, floors and ceilings are recommended to explore passive heating by Narok’s climate is predominantly cool with outdoor storing heat accumulated during the day (avoiding conditions of hourly dry bulb temperatures and relative overheating) to balance the night time low humidity falling within as well as below the comfort zone temperatures to keep them at comfort level. (see Figure 199). Outdoor temperatures can go as low as 5 °C. This indicates that heating is necessary during the • Excessive glazing should be avoided as it can lead under heated period. The chart therefore suggests that the to overheating during the hot period as well as lead most effective strategy for extending the thermal comfort to extensive heat loss at night or during the cold zone would be through passive heating through direct periods. solar heat gain and thermal mass. In addition, internal heat gain from occupants, equipment and lights would • All windows should be airtight to prevent heat contribute to a reduction in heating needs. losses when the outdoor temperatures are below the comfort zone and they should be located on However, during certain times of the year, the hourly opposite walls to allow for cross-ventilation. data points (outdoor dry bulb temperature and relative humidity) fall beyond the comfort zone. Thermal mass is • Additional heating systems such as fireplaces can be effective in extending the comfort zone by absorbing and incorporated in the design. storing daytime solar heat for release at night when the temperatures fall below the comfort zone. • Internal heat gains from occupants, equipment and lights will greatly reduce heating needs.

Bioclimatic recommendations b. Protection against heat gain in the hot According to the climatic data for Narok, the following period design strategies are recommended for: • Buildings should be oriented with the main glazed a. Enabling passive heating windows facing north and south for easier sun control and to minimise overheating during the hot • Careful orientation of buildings with main rooms periods. facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive • Large windows should be avoided on the east and heating during the cold periods. west facing façades.

VOI

Figure 200 Location of Taita-Taveta Climatic Zone HOT SEMI-ARID / SAVANNAH county Latitude 03° 23’ S Longitude 38° 34’ E Altitude 580 m

Figure 201 Voi town center

Source: http://www.d-maps.com/ Source: © Makoto Questions - Own work, CC BY-SA 3.0, https://commons. wikimedia.org/w/index.php?curid=24729216

Figure 202 Location of Voi town in Taita-Taveta county

GEOGRAPHY AND bioclimatic data with the most amount occurring in December. June, July and August present the driest months with no rainfall at Voi, the largest town in Taita - Taveta county, is located all. Relative humidity averages at 67 % annually while the at geographic coordinates of 3° 23’ S 38° 34’ E. At an wind velocity ranges 2.2 – 4.2 m/s with the predominant altitude of 580 m above sea level, the town has savannah wind direction being South and South East. The annual climate with annual temperatures averaging 24.5 °C. The average global solar radiation in Voi is 5.2 kWh/m2. warmest month of the year is February. July and August present the months with the lowest average temperatures of the whole year. About 490 mm of rain falls annually

table 22 VOI monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 25.2 70.0 3.0 5.5 3.5 3.0 30 FEB 26.4 66.0 2.9 5.9 4.2 2.8 30 MAR 26.2 67.0 3.0 5.7 3.8 2.8 70 APR 25.5 70.0 3.5 5.2 3.2 2.8 90 MAY 24.3 71.0 3.4 4.7 3.3 2.5 30 JUN 23.4 64.0 4.0 4.7 3.6 2.3 0 JUL 22.8 62.0 3.9 4.6 3.6 2.3 0 AUG 22.3 64.0 4.2 4.9 3.7 2.4 0 SEP 23.2 64.0 4.0 5.4 3.8 2.6 10 OCT 24.6 64.0 3.0 5.6 3.8 2.8 20 NOV 25.2 70.0 2.7 5.2 3.1 2.9 90 DEC 24.4 76.0 2.2 5.0 3.0 2.8 120

Figure 203 Monthly mean maximum and minimum temperature for Voi T-MiN T-MAX Voi 40 35 32.5 32 30 29.7 28.7 28.6 29.9 29.6 28.5 30 28.2 27.2 27.5 22.2 25 21.6 21.6 21.5 21.2 20.7 21.9 21.1 19.6 19.1 18.4 19.2 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 204 Monthly mean relative humidity for Voi rH-MiN rH-MAX Voi 100 90 86 88 87 85 86 86 81 81 83 83 81 80 59 60 51 51 52 49 41 43 43 41 41 42 [%] 39 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 121 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 205 Monthly average rainfall for Voi

rAiNFALL Voi 350 300 250 200

[mm] 150 120 90 90 100 70 50 30 30 30 20 0 0 0 10 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 206 Polar sun path diagram for Latitude 3° South 122 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 207 Wind rose diagram showing the prevailing wind direction in Voi

Figure 208 Psychrometric chart with passive design strategies overlays for Voi

Interpretation • Use of reflective surfaces (roof) and light coloured external walls are effective in reflecting solar radiation Voi experiences both hot and cold conditions that fall thus minimising solar heat gains and consequently above and below the comfort zone respectively as seen in minimising internal daytime temperatures. Figure 208. Based on the psychrometric chart, a combined effect of natural ventilation, high thermal mass (along b. To balance diurnal temperature range with night ventilation) are the most effective strategies to improve thermal comfort during the overheated • Medium weight building materials with high period. In the case of the under heated period, passive thermal capacity are recommended to balance heating through direct solar heat gain and thermal mass temperature variations between day and night. are effective in expanding the comfort zone when the These materials absorb heat during daytime temperatures fall below the comfort zone. keeping indoor temperatures lower than outdoor temperature. The stored heat is later dissipated at night thereby providing indoor thermal comfort Bioclimatic recommendations when the outdoor temperatures fall below the • In Voi, the design objective should be to balance comfort zone. the conflicting needs of the cold and hot periods to provide comfort. The following design strategies c. To ensure air circulation are recommended: • Openings should be located to take advantage of a. To reduce effects of intense solar radiation prevailing winds and allow for cross-ventilation.

• Compact layout of buildings is recommended to • Ventilation through windows should be kept at a provide mutual shading and minimise exposure to minimum during the daytime to keep hot and dusty solar radiation. air out. However, at night, windows may be opened to provide adequate ventilation for dissipation of • Courtyard design of buildings minimises the impact heat accumulated during the day by walls and the of solar radiation on the outer walls as well as roof to prevent overheating of the interior space. provide cool spaces with the buildings / building layout. • Other ventilation strategies include use of wind catchers, wind towers, solar chimneys, roof- • Buildings should be oriented along the east – west mounted exhaust fans etc. axis with the longer sides facing north and south to prevent solar heat gains. The building’s surface area d. To minimise problems associated with dust exposed to the east and west should be minimised. • Vegetation can be used to filter dust from the air • Openings should be located on the north and south. before it gets into the building. Small openings that are located high on the walls are recommended to facilitate natural ventilation as • Closing windows during daytime prevents dust from well as reduce glare from light reflected from the getting into the building on windy days. Windows ground or surrounding buildings. should be tight-fitting as possible to prevent dust from infiltrating. • Appropriate shading devices are necessary on all openings to decrease heat gain from solar radiation. Use of vegetation, verandas, covered walkways, pergolas etc. is recommended to provide shade to walls, openings and outdoor spaces. 124 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

6.2 TANZANIA

Figure 209 Map of Africa showing the location of TANZANIA

Source: http://www.d-maps.com/ EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 125 BIOCLIMATIC ARCHITECTURAL DESIGN

table 23 Representative towns in Kenya

CITY/TOWN ALTITUDE (M) LATITUDE LONGITUDE CLIMATE ZONE

Arusha 1,400 m 3°32’ S 36° 40’ E Zone 5 – Upland Bukoba 1,200 m 1° 20’ S 31° 49’ E Zone 4 – Great Lakes Dar es Salaam 55 m 6° 48’ S 39° 17’ E Zone 1 – Hot and humid Dodoma 1,120 m 6° 10’ S 35° 45’ E Zone 3 – Hot semi-arid / Savannah Iringa 1,600 m 7° 46’ S 35° 41’ E Zone 5 – Upland Kasulu 1,500 m 4° 34’ S 30° 06’ E Zone 5 – Upland Mbeya 1,800 m 8° 56’ S 33° 28’ E Zone 5 – Upland Mwanza 1,140 m 2° 28’ S 32° 54’ E Zone 4 – Great Lakes Tabora 1,190 m 5° 04’ S 32° 50’ E Zone 3 – Hot semi-arid / Savannah Tanga 35 m 5° 04’ S 39° 05’ E Zone 1 – Hot and humid Zanzibar 15 m 6° 13’ S 39° 12’ E Zone 1 – Hot and humid 126 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

DAR ES SALAAM

Figure 210 Location of Dar es Salaam Climatic Zone HOT AND HUMID Latitude 06° 48’ S Longitude 39° 17’ E Altitude 55 m

Figure 211 Aerial view of Dar es Salaam

Figure 212 Location of Dar es Salaam city

GEOGRAPHY AND bioclimatic data the coolest period occurs in July and August. The average amount of rainfall recorded annually is 990 mm with the Dar es Salaam, situated along the Indian Ocean, is highest recorded amount in April and the least amount the largest city in Tanzania and is located at geographic in July to September. High wind velocity is recorded coordinates of 06° 48’ S, 39° 17’ E and at an elevation of annually at an average of 3.9 m/s with the predominant 55 m above sea level. It enjoys a hot and humid climate wind direction being South South East (SSE). The annual with high temperatures throughout the year (average of average global solar radiation in Dar es Salaam is 4.8 kWh/ 26 °C) as well as high relative humidity (annual mean of m2. 80.3%). The hottest month on average is February while table 24 Dar es Salaam monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 27.8 80.0 4.1 5.1 3.1 2.9 70 FEB 28.2 77.0 4.1 5.2 3.1 2.9 60 MAR 27.8 83.0 4.1 4.7 2.4 3.0 120 APR 26.3 87.0 3.1 3.9 2.0 2.5 260 MAY 25.5 83.0 3.6 4.4 3.1 2.4 180 JUN 24.1 81.0 4.1 4.4 3.6 2.1 30 JUL 23.9 77.0 3.6 4.4 3.4 2.3 20 AUG 23.9 77.0 3.6 4.8 3.4 2.5 20 SEP 24.1 79.0 4.1 4.9 3.3 2.6 20 OCT 25.7 78.0 4.1 5.3 3.9 2.5 40 NOV 26.3 81.0 4.1 5.8 4.5 2.6 80 DEC 27.8 81.0 4.6 5.3 3.7 2.7 90

Figure 213 Monthly mean maximum and minimum temperature for Dar es Salaam T-MiN T-MAX dar es salaam 40 35 31.7 30.9 31.2 30.2 30.4 31 29.6 29.2 28.7 28.6 30 28.1 28.2 24.8 25 24.6 23.3 24.6 25 22.1 21.2 22.5 20.4 19.8 19.5 19.6 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 214 Monthly mean relative humidity for Dar es Salaam rH-MiN rH-MAX dar es salaam 93 96 94 94 94 93 94 95 100 90 89 92 92 77 80 71 71 68 65 65 65 68 61 60 62 61 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 128 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 215 Monthly average rainfall for Dar es Salaam

rAiNFALL dar es salaam 350 300 260 250 200 180

[mm] 150 120 90 100 80 70 60 40 50 30 20 20 20 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 216 Polar sun path diagram for Latitude 6° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 129 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 217 Wind rose diagram showing the prevailing wind direction in Dar es Salaam

Figure 218 Psychrometric chart with passive design strategies overlays for Dar es Salaam

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 130 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation provided by shade-providing vegetation within the space surrounding the building. The outdoor hourly dry bulb temperatures and relative humidity data points indicate that Dar es Salaam is out • Reflective roof surfaces and light coloured external of the comfort zone. The resulting combination of high finishes are appropriate to reflect solar radiation temperatures and high relative humidity causes discomfort and reduce heat gains. in the region throughout the year. Thermal comfort can however be achieved passively through natural ventilation • Lightweight building materials with low thermal for temperatures below 33 °C but beyond the comfort zone. capacity are recommended for walls, floors and This makes it the most appropriate strategy to extend the roofs to allow rapid cooling at night. comfort zone. However, Figure 218 indicates that artificial cooling using fans or air conditioners will be necessary for b. To promote maximum ventilation periods where temperatures are above 33 °C. • Building layout should be widely spaced to avoid obstruction of the wind and allow maximum Bioclimatic recommendations ventilation around and inside buildings. The design objectives and responses for a hot and humid climate like Dar es Salaam’s should be to address issues due • Long and narrow buildings (shallow floor plans) to high temperatures, high relative humidity and high solar are more suited to this climate as they provide radiation levels. The following passive design strategies maximum ventilation. may be used to address the cooling requirements that result from the above climatic characteristics: • North and south facing walls should have large and fully openable openings. These openings a. To provide maximum protection against should preferably be oriented to take advantage of direct and indirect solar radiation the prevailing breezes to facilitate natural airflow. Openings at body level are more effective. • Buildings should be oriented with their long axis running east – west to provide effective shading. • Openings should be located on opposite sides of walls to allow for proper cross-ventilations. Internal • Openings should be located on the north and south walls should also have openings for airflow through facing façades and avoided on the east and west the internal space. facing façades to reduce heat gain from the low early morning and late afternoon sun. • It is advisable to have permanent vents / openings close to the ceiling / roof to prevent the built up of • Appropriate shading devices should be located on hot air and encourage thermal air movement. all openings. These can be in form of extended roof eaves, covered verandas and porches etc. • Ventilated double roofs enhance ventilation of the roof minimising overheating. • Additional solar radiation protection may be

Figure 219 Narrow cross section of the tower allows for maximum daylight penetration eliminating the need for artificial lighting during the daytime

Exim Tower, Dar es Salaam Source: http://www.spasmindia.com/ © Spasm Design Architects EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 131 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 220 Extensive balconies on every floor create shaded terraces that offer comfortable outdoor spaces (top). Glazed surfaces of the buildings are shaded by a stainless-steel mesh that reflects solar radiation minimising heat gain (bottom).

Figure 221 Large overhangs provide sun shading of the large windows minimising unwanted solar radiation. The also offer protection from driving rain and prevents glare from the sky. Large operable windows allow fresh cool breeze to penetrate the building enabling cross ventilation, thereby reducing energy loads associated with cooling.

AON Insurance Headquarters, Dar es Salaam Source: http://www.spasmindia.com/ © Spasm Design Architects 132 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 222 Provision of a floating sun solar roof, external shading louvres and use of light- Coloured external surface prevent heat gain by reflecting unwanted solar radiation

Umoja House, Dar es Salaam Source: http://www.bdp.com/en/projects/p-z/Umoja-House/ EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 133 BIOCLIMATIC ARCHITECTURAL DESIGN

DODOMA

Figure 223 Location of Dodoma Climatic Zone HOT SEMI-ARID / SAVANNAH Latitude 06° 10’ S Longitude 35° 45’ E Altitude 1,120 m

Figure 224 View of Dodoma city centre

Figure 225 Location of Dodoma city

GEOGRAPHY AND bioclimatic data January is recorded as the month with the most amount of rainfall at an average of 150 mm. Relative humidity ranges Dodoma is the national capital of Tanzania located at 55 – 71% while the wind velocity averages 3.4 m/s with geographic coordinates 6° 10’ S, 35° 45’ E and at an altitude the predominant wind direction being East. The annual of 1,120 m above sea level. Its climate is categorised as average global solar radiation in Dodoma is 5.6 kWh/m2. savannah characterised by mean annual temperatures of 22.6 °C and low amounts of rainfall (annual average of 540 mm). The warmest months on average are November and December while the coolest month on average is July.

table 25 DODOMA monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 23.9 68.0 3.5 5.4 4.2 2.5 150 FEB 23.0 70.0 3.5 5.6 4.4 2.6 100 MAR 23.3 71.0 3.5 5.6 4.2 2.6 130 APR 22.5 71.0 2.7 5.1 4.2 2.3 50 MAY 22.0 65.0 3.1 5.3 5.0 2.1 0 JUN 21.1 63.0 3.5 5.2 5.4 1.8 0 JUL 19.7 61.0 3.1 5.4 5.6 1.8 0 AUG 20.6 60.0 3.1 5.6 5.3 2.0 0 SEP 21.9 58.0 3.5 6.1 5.5 2.2 0 OCT 24.0 55.0 3.5 6.4 5.4 2.4 0 NOV 24.7 58.0 3.5 6.3 5.2 2.5 20 DEC 24.7 65.0 3.9 5.8 4.9 2.4 90

Figure 226 Monthly mean maximum and minimum temperature for Dodoma T-MiN T-MAX dodoma 40 35 28.5 28.6 27.9 30 26.9 26.4 26.7 25.7 25.7 26.6 25.1 24.1 25.3 25 21.5 20.9 20 20.7 19.7 19.4 18.5 19.5 C] 17.4 17.5

° 20

[ 15.7 16.2 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 227 Monthly mean relative humidity for Dodoma rH-MiN rH-MAX dodoma 100 86 86 85 80 80 79 77 77 78 80 75 74 74

55 55 58 57 60 51 49 46 45 42 42 [%] 41 38 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 135 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 228 Monthly average rainfall for Dodoma

rAiNFALL dodoma 350 300 250 200 150

[mm] 150 130 100 90 100 50 50 20 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 229 Polar sun path diagram for Latitude 6° South 136 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 230 Wind rose diagram showing the prevailing wind direction in Dodoma

Figure 231 Psychrometric chart with passive design strategies overlays for Dodoma

Interpretation ground or surrounding buildings.

Dodoma experiences both hot and cold conditions • Appropriate shading devices are necessary on all that fall above and below the comfort zone respectively openings to decrease heat gain from solar radiation. as seen in Figure 230. Based on the psychrometric chart, Use of vegetation, verandas, covered walkways, a combined effect of natural ventilation, high thermal pergolas etc. is recommended to provide shade to mass (along with night ventilation) are the most effective walls, openings and outdoor spaces. strategies to improve thermal comfort during the overheated period. In the case of the under heated period, • Use of reflective surfaces (roof) and light coloured passive heating through direct solar heat gain and thermal external walls are effective in reflecting solar radiation mass are effective in expanding the comfort zone when thus minimising solar heat gains and consequently the temperatures fall below the comfort zone. minimising internal daytime temperatures.

Bioclimatic recommendations b. To balance diurnal temperature range In Dodoma, the design objective should be to balance • Medium weight building materials with high thermal the conflicting needs of the cold and hot periods to capacity are recommended to balance temperature provide comfort. The following design strategies are variations between day and night. These materials recommended for: absorb heat during daytime keeping indoor temperatures lower than outdoor temperature. a. To reduce effects of intense solar radiation The stored heat is later dissipated at night thereby providing indoor thermal comfort when the outdoor • Compact layout of buildings is recommended to temperatures fall below the comfort zone. provide mutual shading and minimise exposure to solar radiation. c. To ensure air circulation

• Courtyard design of buildings minimises the impact • Openings should be located to take advantage of of solar radiation on the outer walls as well as provide prevailing winds and allow for cross-ventilation. cool spaces with the buildings / building layout. • Ventilation through windows should be kept at a • Buildings should be oriented along the east – west axis minimum during the daytime to keep hot and dusty with the longer sides facing north and south in order air out. However, at night, windows may be opened to prevent solar heat gains. The building’s surface area to provide adequate ventilation for dissipation of exposed to the east and west should be minimised. heat accumulated during the day by walls and the roof to prevent overheating of the interior space. • Openings should be located on the north and south. Small openings that are located high on the walls • Other ventilation strategies include use of wind are recommended to facilitate natural ventilation as catchers, wind towers, solar chimneys, roof- well as reduce glare from light reflected from the mounted exhaust fans etc.

Figure 232 USE OF LIGHT-COLOURED SURFACES AND SHADING SCREEN TO MINIMISE HEAT GAINS

CCM Conference centre, Dodoma © UN-Habitat / Jerusha NGUNGUI 138 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

MBEYA

Figure 233 Location of Mbeya Climatic Zone UPLAND Latitude 08° 56’ S Longitude 33° 28’ E Altitude 1,707 m

Figure 234 View of Mbeya town

Figure 235 Location of Mbeya town

GEOGRAPHY AND bioclimatic data rainfall per year is 800 mm with the heaviest rainy period occurring between December to April. Between May and Mbeya town, at the southwestern part of Tanzania November, there is little to no rainfall. Relative humidity and surrounded by mountains, is located at geographic averages at 60.8% annually while the wind velocity ranges coordinates of 08° 56’ S, 33° 28’ E. At an altitude of 1.8 – 5.4 m/s with the predominant wind direction being 1,707 m above sea level, it enjoys an upland climate South East. The annual average global solar radiation in characterised by cool temperatures (annual mean of 19.1 this town is 6.2 kWh/m2. °C) with the coolest months being June and July while the warmest month on average being October. Average table 26 MBEYA monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 19.3 72.0 1.8 5.5 4.7 2.3 190 FEB 19.2 74.0 2.2 6.1 4.9 2.7 150 MAR 19.5 73.0 3.3 5.6 4.4 2.6 150 APR 19.2 70.0 5.0 5.9 5.5 2.2 110 MAY 18.4 65.0 5.3 6.4 7.8 1.5 10 JUN 16.7 59.0 5.4 6.4 8.3 1.1 0 JUL 16.9 52.0 5.4 6.3 7.4 1.4 0 AUG 18.2 53.0 5.1 6.5 7.2 1.7 0 SEP 20.1 48.0 4.9 6.8 6.9 1.9 0 OCT 21.5 46.0 4.0 7.1 6.9 2.0 10 NOV 20.3 54.0 2.7 6.3 5.3 2.4 50 DEC 19.6 64.0 1.8 5.4 4.1 2.4 130

Figure 236 Monthly mean maximum and minimum temperature for Mbeya T-MiN T-MAX mbeya 40 35 30 26.1 24.8 24.2 22.3 22.6 22.8 22.4 22.2 22.9 22.8 25 20.6 21.1

° C] 20 16.4 17 16.4 16.5 [ 15.9 16.2 16.1 15.5 14.9 13.8 15 13 12.9 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 237 Monthly mean relative humidity for Mbeya rH-MiN rH-MAX mbeya 100 90 87 87 85 81 78 80 74 71 67 69 65 62 58 59 59 54 60 49 49 43 [%] 36 37 39 40 33 32

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 140 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 238 Monthly average rainfall for Mbeya

rAiNFALL mbeya 350 300 250 190 200 150 150

[mm] 150 130 110 100 50 50 10 10 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 239 Polar sun path diagram for Latitude 8° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 141 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 240 Wind rose diagram showing the prevailing wind direction in Mbeya

Figure 241 Psychrometric chart with passive design strategies overlays for Mbeya

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 142 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation overheating) to balance the night time low temperatures to keep them at comfort level. In Mbeya, most of the hourly points of outdoor dry bulb temperature and relative humidity fall within the • Excessive glazing should be avoided as it can lead comfort zone. However, a substantial portion falls below to overheating during the hot period as well as lead the comfort zone as seen in Figure 241. This means that to extensive heat loss at night or during the cold during that period, space heating is necessary in order to periods. extend the limit of comfort zone. This can be done through passive heating through direct solar heat gain and thermal • All windows should be airtight to prevent heat mass. Further, internal heat gain from equipment, lights losses when the outdoor temperatures are below and occupants are also helpful in extending the thermal the comfort zone and they should be located on comfort and reducing heading heating demand. opposite walls to allow for cross-ventilation.

• Additional heating systems such as fireplaces can be Bioclimatic recommendations incorporated in the design. According to the climatic data for Mbeya, the following design strategies are recommended for: • Internal heat gains from occupants, equipment and lights will greatly reduce heating needs. a. Enabling passive heating b. Protection against heat gain in the hot • Careful orientation of buildings with main rooms period facing north east is appropriate to allow a certain amount of solar radiation to penetrate for passive • Buildings should be oriented with the main glazed heating during the cold periods. windows facing north and south for easier sun control and to minimise overheating during the hot • The floor plan should be organised such that it periods. allows the sun to penetrate into daytime spaces during the cold periods. • Large windows should be avoided on the east and west facing façades. • Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold • Appropriate sun shading devices should be periods. incorporated to keep out the solar radiation and glare during certain hours of the day during the hot • Medium weight walls, floors and ceilings are periods. recommended to explore passive heating by storing heat accumulated during the day (avoiding

Figure 242 Sunshading

Mbeya University of Science and Technology, Tanzania Source: http://www.mbeya.go.tz/ EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 143 BIOCLIMATIC ARCHITECTURAL DESIGN

MWANZA

Figure 243 Location of Mwanza Climatic Zone GREAT LAKES Latitude 02° 28’ S Longitude 32° 54’ E Altitude 1,140 m

Figure 244 Aerial view of Mwanza town

Source: http://www.d-maps.com/ Source: http://bestplacestotravel.info/page/mwanza/tanzania/default.html

Figure 245 Location of Mwanza town

GEOGRAPHY AND bioclimatic data least amount occurs from June to August. The average annual temperature is 23.3 °C with the warmest period Mwanza, a port-town situated on the shores of Lake on average occurring in October while the coolest is Victoria, is the second largest city in Tanzania after Dar July. Relative humidity averages at 66.5% annually while es Salaam. It is located at geographic coordinates of 02° high wind velocity is recorded throughout the year at an 28’ S, 32° 54’ E and at an altitude of 1,140 m above average of 5.1 m/s and the predominant wind direction sea level. Its climate is characterised by rainfall being being North West and South East. The annual average recorded throughout the year with an average amount global solar radiation in Mwanza is 5.4 kWh/m2. of 930 mm. The most amount occurs in March while the

table 27 MWANZA monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 23.5 71.0 6.2 5.3 4.3 2.4 90 FEB 23.0 74.0 6.2 5.4 4.5 2.3 100 MAR 23.6 73.0 6.2 5.8 4.9 2.3 150 APR 23.0 74.0 5.1 5.4 4.2 2.5 140 MAY 23.3 70.0 4.1 5.3 5.0 2.0 90 JUN 22.7 64.0 3.6 5.6 5.6 1.9 10 JUL 22.5 58.0 3.1 5.6 5.5 2.0 10 AUG 23.1 56.0 3.6 5.8 5.1 2.2 10 SEP 23.3 60.0 5.1 5.5 4.5 2.4 40 OCT 24.2 59.0 5.7 5.6 4.1 2.6 40 NOV 23.6 68.0 5.7 5.3 3.6 2.8 110 DEC 23.2 71.0 6.2 4.7 3.2 2.5 140

Figure 246 Monthly mean maximum and minimum temperature for Mwanza T-MiN T-MAX mWanza 40 35 29 29.2 29.2 28.5 29.2 29.8 28.8 28.5 30 27.8 28.3 27.8 28 25 18.4 18.4 18.8 18.8 18.4 C] 18.2 17.3 17.9 17.5 18 17.6 18.1

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 247 Monthly mean relative humidity for Mwanza rH-MiN rH-MAX mWanza 100 91 93 93 92 90 87 88 83 80 82 79 80 76

60 53 54 56 53 51 51 48 44 [%] 37 39 39 38 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 145 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 248 Monthly average rainfall for Mwanza

rAiNFALL mWanza 350 300 250 200 150 140 140 [mm] 150 110 90 100 90 100 40 40 50 10 10 10 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 249 Polar sun path diagram for Latitude 2° South 146 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 250 Wind rose diagram showing the prevailing wind direction in Mwanza

Figure 251 Psychrometric chart with passive design strategies overlays for Mwanza

Interpretation facing façades to reduce heat gain from the low early morning and late afternoon sun. Most of the outdoor hourly dry bulb temperature and relative humidity data point fall within the comfort zone. • Appropriate shading devices should be located on However, the area experiences under heated periods with all openings. These can be in form of extended roof temperatures falling below the comfort zone to 15 °C eaves, vertical fins, covered verandas and porches as well as overheated periods with temperatures rising etc. (Figure 252). to 32 °C. Based on the psychrometric chart (see Figure 251), a combined effect of natural ventilation, high • Additional solar radiation protection may be thermal mass (along with night ventilation) are the most provided by shade-providing vegetation within the effective strategies to improve thermal comfort during the space surrounding the building. overheated period. In the case of the under heated period, passive heating through direct solar heat gain and thermal • Reflective roof surfaces and light coloured external mass are effective in expanding the comfort zone when finishes are appropriate to reflect solar radiation the temperatures fall below the comfort zone. and minimise heat gains.

Bioclimatic recommendations b. To promote maximum ventilation In Mwanza, the design objective should be to balance • Building layout should be widely spaced to avoid the conflicting needs of the cold and hot periods to provide obstruction of the wind and allow maximum comfort. The following passive design strategies may be ventilation around and inside buildings. used to address the cooling and heating requirements that result from the above climatic characteristics: • Long and narrow buildings (shallow floor plans) are more suited to this climate as they provide a. To provide maximum protection against maximum airflow through them. direct and indirect solar radiation • North and south facing walls should have large • Buildings should be oriented with their long axis and fully openable openings. These openings running east – west to provide effective shading. should preferably be oriented to take advantage of the prevailing breezes to facilitate natural airflow. • Openings should be located on the north and south Openings at body level are more effective. facing façades and avoided on the east and west

Figure 252 Balconies and roof overhangs act as sun shading elements thus minimising solar Heat gain

Mwanza Train Station Source: http://www.wikiwand.com/en/Mwanza 148 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

• Openings should be located on opposite sides of c. To enabling passive heating walls to allow for proper cross-ventilations. Internal walls should also have openings for airflow through • Medium weight walls, floors and ceilings are the internal space. recommended to explore passive solar gains by storing heat accumulated during the day (avoiding • It is advisable to have permanent vents / openings overheating) to balance the night time low close to the ceiling / roof to prevent the built up of temperatures to keep them at comfort level. hot air and encourage thermal air movement. • Excessive glazing should be avoided as it can lead • Ventilated double roofs enhance ventilation of the to overheating during the hot period as well as lead roof minimising overheating. to extensive heat loss at night or during the cold periods.

• All windows should be airtight to prevent heat losses when the outdoor temperatures are below the comfort zone. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 149 BIOCLIMATIC ARCHITECTURAL DESIGN

TABORA

Figure 253 Location of Tabora Climatic Zone HOT SEMI-ARID / SAVANNAH Latitude 05° 04’ S Longitude 32° 50’ E Altitude 1,190 m

Figure 254 A street in tabora town

Source: http://www.d-maps.com/ Source: https://www.odysseysafaris.com/tag/adventure/page/24/

Figure 255 Location of Tabora

GEOGRAPHY AND bioclimatic data it occurring from November through to April. The most amount is seen in December, at an average of 170 mm. Tabora town is located at geographic coordinates of June to September present the driest months with no 05° 04’ S, 32° 50’ E and at an altitude of 1,190 m above rainfall at all. Relative humidity averages at 60.5% while sea level. The town has savannah climate with annual the predominant wind direction being East South East temperatures averaging 23.1 °C. The warmest month of (ESE). The annual average global solar radiation in Tabora the year is October while June and July present the months is 5.6 kWh/m2. with the lowest average temperatures of the whole year. About 820 mm of rain falls annually with most of

table 28 TABORA monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 22.6 72.0 0.4 5.4 4.8 2.3 120 FEB 22.8 74.0 0.4 5.5 4.6 2.4 120 MAR 23.2 75.0 0.4 5.8 5.2 2.1 160 APR 22.3 72.0 0.4 5.3 4.4 2.3 130 MAY 22.6 63.0 0.4 5.6 5.4 2.1 20 JUN 21.5 57.0 0.6 5.8 6.4 1.6 0 JUL 21.5 51.0 0.6 5.7 5.5 1.9 0 AUG 22.7 48.0 0.6 6.1 6.0 1.9 0 SEP 24.2 46.0 0.6 5.7 4.5 2.5 0 OCT 25.7 44.0 0.6 6.0 4.9 2.4 10 NOV 24.7 55.0 0.6 5.4 4.0 2.5 90 DEC 23.2 69.0 0.4 4.9 3.6 2.5 170

Figure 256 Monthly mean maximum and minimum temperature for Tabora T-MiN T-MAX tabora 40

35 30.7 28.3 28.3 29.3 29.3 30 27.1 26.5 27.1 26.1 26 27.4 27.2 25 20.7 20.3 18.4 19.3 19.2 C] 18.1 17.5 18.1 18.2 17.4 17.2 18.2 ° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 257 Monthly mean relative humidity for Tabora rH-MiN rH-MAX tabora 100 93 94 90 89 87 81 80 71 70 66 62 62 57 59 60 55 55 56 54 46

[%] 41 36 39 40 33 31 30

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 151 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 258 Monthly average rainfall for Tabora

rAiNFALL tabora 350 300 250 200 160 170

[mm] 150 120 120 130 90 100 50 20 10 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 259 Polar sun path diagram for Latitude 5° South 152 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 260 Wind rose diagram showing the prevailing wind direction in Tabora

Figure 261 Psychrometric chart with passive design strategies overlays for Tabora

Interpretation • Appropriate shading devices are necessary on all openings to decrease heat gain from solar radiation. Tabora experiences both hot and cold conditions that fall Use of vegetation, verandas, covered walkways, above and below the comfort zone respectively as seen in pergolas etc. is recommended to provide shade to Figure 261. Based on the psychrometric chart, a combined walls, openings and outdoor spaces. effect of natural ventilation and thermal mass (along with night ventilation) are the most effective strategies • Use of reflective surfaces (roof) and light coloured to improve thermal comfort during the overheated external walls are effective in reflecting solar radiation period. In the case of the under heated period, passive thus minimising solar heat gains and consequently heating through direct solar heat gain and thermal mass minimising internal daytime temperatures. are effective in expanding the comfort zone when the temperatures fall below the comfort zone. b. To balance diurnal temperature range

• Medium weight building materials with high Bioclimatic recommendations thermal capacity are recommended to balance In Tabora, the design objective should be to balance the temperature variations between day and night. These conflicting needs of the cold and hot periods to provide materials absorb heat during daytime keeping indoor comfort. The following design strategies are recommended temperatures lower than outdoor temperature. for: The stored heat is later dissipated at night thereby providing indoor thermal comfort when the outdoor a. To reduce effects of intense solar radiation temperatures fall below the comfort zone.

• Compact layout of buildings is recommended to c. To ensure air circulation provide mutual shading and minimise exposure to solar radiation. • Openings should be located to take advantage of prevailing winds and allow for cross-ventilation. • Courtyard design of buildings minimises the impact of solar radiation on the outer walls as well as provide • Ventilation through windows should be kept at a cool spaces with the buildings / building layout. minimum during the daytime to keep hot and dusty air out. However, at night, windows may be opened • Buildings should be oriented along the east – west to provide adequate ventilation for dissipation of axis with the longer sides facing north and south to heat accumulated during the day by walls and the prevent solar heat gains. The building’s surface area roof to prevent overheating of the interior space. exposed to the east and west should be minimised. • Other ventilation strategies include use of wind • Openings should be located on the north and south. catchers, wind towers, solar chimneys, roof-mounted Small openings that are located high on the walls are exhaust fans etc. recommended to facilitate natural ventilation as well as reduce glare from light reflected from the ground or surrounding buildings. 154 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

TAnga

Figure 262 Location of Tanga Climatic Zone HOT AND HUMID Latitude 05° 04’ S Longitude 39° 05’ E Altitude 35 m

Figure 263 A SECTION OF TANGA TOWN

Source: http://www.d-maps.com/ Source: https://static.panoramio.com.storage.googleapis.com/photos/ original/121372289.jpg

Figure 264 Location of Tanga town

GEOGRAPHY AND bioclimatic data (average of 26.4 °C). The warmest month of the year is March. The lowest average temperatures of the year are Tanga, the headquarters of Tanga region and one in July making it the coolest month. The average amount of the sea port cities of Tanzania, is situated along the of rainfall recorded annually is 1,290 mm with the highest Indian Ocean coast of Tanzania. It is located at geographic recorded amount in May and the least amount in January. coordinates of 05° 04’ S, 39° 05’ E at an altitude of 35 High wind velocity is recorded annually at an average of m above sea level. It enjoys a hot and humid climate 4.5 m/s with the predominant wind direction being South. characterised by high relative humidity (annual mean The annual average global solar radiation in Tanga is 5.0 of 80.9%) and high temperatures throughout the year kWh/m2. table 29 tanga monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 27.9 77.0 4.9 5.3 3.5 2.8 30 FEB 28.2 77.0 5.4 5.5 3.5 3.0 40 MAR 28.4 80.0 4.5 5.4 3.6 2.7 120 APR 27.0 85.0 4.3 4.7 2.8 2.7 220 MAY 26.1 84.0 4.8 4.5 3.2 2.4 320 JUN 24.6 83.0 4.9 4.6 3.7 2.2 70 JUL 24.3 81.0 4.8 4.7 3.5 2.4 50 AUG 24.5 80.0 4.4 4.9 3.5 2.4 70 SEP 24.7 81.0 4.1 5.0 3.7 2.4 80 OCT 26.0 79.0 3.7 5.4 3.7 2.7 110 NOV 26.9 83.0 4.1 5.3 3.5 2.8 100 DEC 27.6 81.0 4.6 5.3 3.8 2.6 80

Figure 265 Monthly mean maximum and minimum temperature for Tanga T-MiN T-MAX tanga 40 35 32 32.4 32.3 31.4 30.4 29.4 29.4 30.3 30 28.1 27.8 28.2 28.1 24.2 24.6 24 23.8 23 22.7 23.5 24 25 21.5 21 21.1 21.4 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 266 Monthly mean relative humidity for Tanga

rH-MiN rH-MAX tanga 95 96 100 92 91 93 94 94 93 93 93 93 93

80 73 72 70 71 66 68 67 66 67 62 62 65 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 156 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 267 Monthly average rainfall for Tanga

rAiNFALL tanga 350 320 300

250 220 200

[mm] 150 120 110 100 100 70 70 80 80 40 50 50 30 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 268 Polar sun path diagram for Latitude 5° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 157 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 269 Wind rose diagram showing the prevailing wind direction in Tanga

Figure 270 Psychrometric chart with passive design strategies overlays for Tanga

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 158 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Reflective roof surfaces and light coloured external finishes are appropriate to reflect solar radiation Figure 270 shows that Tanga lies outside the comfort and reduce heat gains. zone throughout the year. The resulting combination of high hourly outdoor dry bulb temperatures and relative • Lightweight building materials with low thermal humidity causes discomfort. In order to improve thermal capacity are recommended for walls, floors and comfort, natural ventilation is the most appropriate strategy roofs to allow rapid cooling at night. to adopt. b. To promote maximum ventilation However, at certain times of the year, temperature go above the natural ventilation zone and mechanical cooling • Building layout should be widely spaced to avoid may be necessary to provide thermal comfort. obstruction of the wind and allow maximum ventilation around and inside buildings.

Bioclimatic recommendations • Long and narrow buildings (shallow floor plans) The design objectives and responses for a hot and humid are more suited to this climate as they provide climate like Tanga’s should be to address issues due to maximum ventilation. high temperatures, high relative humidity and high solar radiation levels. The following passive design strategies • North and south facing walls should have large may be used to address the cooling requirements that and fully openable openings. These openings result from the above climatic characteristics: should preferably be oriented to take advantage of the prevailing breezes to facilitate natural airflow. a. To provide maximum protection against Openings at body level are more effective. direct and indirect solar radiation • Openings should be located on opposite sides of • Buildings should be oriented with their long axis walls to allow for proper cross-ventilations. Internal running east – west to provide effective shading. walls should also have openings for airflow through the internal space. • Openings should be located on the north and south facing façades and avoided on the east and west • It is advisable to have permanent vents / openings facing façades to reduce heat gain from the low close to the ceiling / roof to prevent the built up of early morning and late afternoon sun. hot air and encourage thermal air movement.

• Appropriate shading devices should be located on • Ventilated double roofs enhance ventilation of the all openings. These can be in form of extended roof roof minimising overheating. eaves, covered verandas and porches etc.

• Additional solar radiation protection may be provided by shade-providing vegetation within the space surrounding the building. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 159 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 271 Lightweight materials such as bamboo, shade nets and timber have been used in the building’s façades allowing for cross ventilation through the openings in these permeable materials. Raised floors minimise heat gain from the ground WHile open eaves and open windows covered with wire and mosquito mesh maximise natural ventilation by promoting air flow thus providing thermal comfort.

The Magoda Project, Tanga Source: http://ingvartsen.dk/ © Ingvartsen Architects / Konstantin IKONOMIDIS 160 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

ZANZIBAR

Figure 272 Location of Zanzibar Climatic Zone HOT AND HUMID Latitude 06° 13’ 6 Longitude 39° 12’ E Altitude 15 m

Figure 273 Aerial view of Zanzibar town

Source: http://www.d-maps.com/ Source: http://networkutazasiiroda.network.hu/

Figure 274 Location of Zanzibar town on Zanzibar Island

GEOGRAPHY AND bioclimatic data year (average of 26.9 °C). The warmest month of the year is March. The lowest average temperatures of the year are Zanzibar city is found in Zanzibar, the main and largest in July making it the coolest month. The average amount island of the Zanzibar Archipelago that lies off the off of rainfall recorded annually is 1,350 mm with the highest the coast of East Africa in the Indian Ocean. It is located recorded amount in April and the least amount in July. at geographic coordinates of 06° 13’ S, 39° 12’ E at an High wind velocity is recorded annually at an average of altitude of 15 m above sea level. It enjoys a hot and humid 4.9 m/s with the predominant wind direction being South climate characterised by high relative humidity (annual and South East. The annual average global solar radiation mean of 80%) and high temperatures throughout the in Zanzibar is 4.9 kWh/m2. table 30 Zanzibar monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 28.4 75.0 5.1 5.0 3.2 2.7 50 FEB 28.6 75.0 5.1 5.2 3.3 2.7 60 MAR 29.0 80.0 5.1 4.9 2.9 2.8 140 APR 27.2 87.0 4.1 4.4 2.6 2.5 320 MAY 26.4 85.0 4.6 4.6 3.7 2.2 280 JUN 25.5 82.0 5.1 4.8 4.0 2.2 50 JUL 25.1 80.0 4.6 4.9 4.3 2.1 20 AUG 25.4 78.0 4.6 5.2 3.8 2.5 30 SEP 25.3 79.0 5.1 5.2 3.6 2.6 40 OCT 26.5 78.0 5.1 5.4 3.7 2.7 60 NOV 27.5 81.0 5.1 5.0 3.2 2.8 170 DEC 28.1 79.0 5.6 4.8 2.7 2.9 130

Figure 275 Monthly mean maximum and minimum temperature for Zanzibar T-MiN T-MAX zanzibar 40 32.5 35 31.5 32.1 31 31.4 31.3 30.4 30.2 29.6 29.4 30.2 29.9 30 25.4 25.3 25.7 24.9 24.2 23 23.7 25 21.8 21.1 21 20.8 22.1 C]

° 20 [ 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 276 Monthly mean relative humidity for Zanzibar rH-MiN rH-MAX zanzibar 96 96 96 100 92 95 94 94 93 95 88 89 91

80 75 73 68 68 67 66 62 61 63 60 62 60 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC 162 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 277 Monthly average rainfall for Zanzibar

rAiNFALL zanzibar 350 320 300 280 250

200 170 140 [mm] 150 130 100 60 60 50 50 40 50 20 30 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 278 Polar sun path diagram for Latitude 6° South EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 163 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 279 Wind rose diagram showing the prevailing wind direction in ZANZIBAR

Figure 280 Psychrometric chart with passive design strategies overlays for ZANZIBAR

C Comfort Zone EC Evaporative Cooling V Natural Ventilation PH Passive Heating TM Thermal Mass AC Air Conditioning HTM High Thermal Mass 164 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Interpretation • Additional solar radiation protection may be provided by shade-providing vegetation within the Figure 280 shows that Zanzibar has its hourly outdoor space surrounding the building. dry bulb temperatures and relative humidity data points out of the comfort zone. The resulting combination of • Reflective roof surfaces and light coloured external high temperatures and relative humidity causes discomfort. finishes are appropriate to reflect solar radiation According to the psychrometric chart, thermal comfort can and reduce heat gains. be achieved through natural ventilation for temperatures below 33 °C making it the most appropriate design strategy • Lightweight building materials with low thermal to extend the comfort zone. capacity are recommended for walls, floors and roofs to allow rapid cooling at night. However, at certain periods, outdoor dry bulb temperature and relative humidity fall outside the limits of natural b. To promote maximum ventilation ventilation, thereby necessitating the use of mechanical cooling and dehumidification to improve thermal comfort. • Building layout should be widely spaced to avoid obstruction of the wind and allow maximum Bioclimatic recommendations ventilation around and inside buildings. The design objectives and responses for a hot and humid • Long and narrow buildings (shallow floor plans) climate like Zanzibar’s should be to address issues due to are more suited to this climate as they provide high temperatures, high relative humidity and high solar maximum ventilation. radiation levels. The following passive design strategies may be used to address the cooling requirements that • North and south facing walls should have large result from the above climatic characteristics: and fully openable openings. These openings should preferably be oriented to take advantage of a. To provide maximum protection against the prevailing breezes to facilitate natural airflow. direct and indirect solar radiation Openings at body level are more effective.

• Buildings should be oriented with their long axis • Openings should be located on opposite sides of running east – west to provide effective shading. walls to allow for proper cross-ventilations. Internal walls should also have openings for airflow through • Openings should be located on the north and south the internal space. facing façades and avoided on the east and west facing façades to reduce heat gain from the low • It is advisable to have permanent vents / openings early morning and late afternoon sun. close to the ceiling / roof to prevent the built up of hot air and encourage thermal air movement. • Appropriate shading devices should be located on all openings. These can be in form of extended roof • Ventilated double roofs enhance ventilation of the eaves, covered verandas and porches etc. roof minimising overheating. EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 165 BIOCLIMATIC ARCHITECTURAL DESIGN

6.3 UGANDA

Figure 281 Map of Africa showing the location of UGANDA

Source: http://www.d-maps.com/ 166 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

table 31 Representative towns in Kenya

CITY/TOWN ALTITUDE (M) LATITUDE LONGITUDE CLIMATE ZONE

Arua 1,200 m 3° 02′ N 30° 54′ E Zone 3 – Hot semi-arid / Savannah Fort Portal 1,480 m 0° 39′ N 30° 16′ E Zone 5 – Upland Gulu 1,100 m 2° 46′ N 32° 17′ E Zone 3 – Hot semi-arid / Savannah Hoima 1,120 m 1° 25′ N 31° 21′ E Zone 3 – Hot semi-arid / Savannah Iganga 1,120 m 0° 36′ N 33° 29′ E Zone 3 – Hot semi-arid / Savannah Jinja 1,200 m 0° 25′ N 33° 12′ E Zone 4 – Great Lakes Kabale 1,800 m 1° 15′ S 29° 59′ E Zone 5 – Upland Kampala 1,190 m 0° 19’ N 32° 34’ E Zone 4 – Great Lakes Kasese 1,000 m 0° 11’ N 30° 05’ E Zone 3 – Hot semi-arid / Savannah Lira 1,080 m 2° 14’ N 32° 54’ E Zone 3 – Hot semi-arid / Savannah Mbale 1,143 m 1° 04’ N 34° 10’ E Zone 5 – Upland Soroti 1,080 m 1° 42′ N 33° 36′ E Zone 3 – Hot semi-arid / Savannah Tororo 1,185 m 0° 41’ N 34° 10’ E Zone 5 – Upland EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 167 BIOCLIMATIC ARCHITECTURAL DESIGN

KAMPALA

Figure 282 Location of Kampala Climatic Zone GREAT LAKES Latitude 00° 19’ N Longitude 32° 34’ E Altitude 1,190 m

Figure 283 View of Kampala city

Source: http://www.d-maps.com/ Source: http://www.enjoyuganda.info/wp-content/uploads/2011/11/Kampala003. jpg

Figure 284 Location of Kampala city

GEOGRAPHY AND bioclimatic data warmest period on average occurring between February and March while the coolest months on average being Kampala, the capital and largest city of Uganda, is August and September. The city experiences high relative located at geographic coordinates 0° 19’ N, 32° 34’ E humidity throughout the year at an average of 82.1%. at an altitude of 1,190 m above sea level. Its climate is High wind velocity is recorded throughout the year at an characterised by rainfall being recorded throughout the average of 5.1 m/s and the predominant wind direction year with an average amount of 1,211 mm. The most being South. The annual average global solar radiation in amount occurs in April while the least amount occurs in Kampala is 4.8 kWh/m2. July. The average annual temperature is 21.5 °C with the

table 32 KAMPALA monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 22.0 80.0 6.2 4.9 4.0 2.2 58 FEB 22.0 80.0 6.2 5.0 3.9 2.2 61 MAR 22.3 81.0 6.2 5.1 4.1 2.2 122 APR 21.5 85.0 5.1 4.8 3.4 2.4 179 MAY 21.8 84.0 4.1 4.8 3.9 2.1 132 JUN 20.9 85.0 3.6 4.4 3.3 2.3 66 JUL 20.9 81.0 3.1 4.3 3.0 2.3 53 AUG 20.7 82.0 3.6 4.6 3.0 2.5 88 SEP 20.7 83.0 5.1 5.1 3.7 2.5 101 OCT 21.5 81.0 5.7 4.8 3.3 2.5 118 NOV 21.5 82.0 5.7 4.9 3.5 2.4 139 DEC 21.7 81.0 6.2 5.0 4.1 2.3 94

Figure 285 Monthly mean maximum and minimum temperature for Kampala T-MiN T-MAX KamPala 40 35 27.5 28 27.8 27.3 30 26.3 26.5 25.8 26 25.9 26.6 26.9 26.8 25

C] 17.1 17.2 ° 20 16.7 17 16.2 16.3 16.4 16.4 [ 16.1 16.1 15.8 15.2 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 286 Monthly mean relative humidity for Kampala rH-MiN rH-MAX KamPala 97 97 98 97 97 98 100 96 96 96 96 95 96

80 70 68 69 64 65 64 67 61 60 63 63 63 60 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 169 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 287 Monthly average rainfall for Kampala

rAiNFALL KamPala 350 300 250 200 179 139

[mm] 132 150 122 118 101 88 94 100 66 58 61 53 50 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 288 Polar sun path diagram for Latitude 0° (Equator) 170 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 289 Wind rose diagram showing the prevailing wind direction in Kampala

Figure 290 Psychrometric chart with passive design strategies overlays for Kampala

Interpretation b. To promote maximum ventilation

The psychrometric chart Figure 290 shows that the Great • Building layout should be widely spaced to Lake climate of Kisumu experiences a few hours of thermal avoid obstruction of the wind and allow maximum comfort with most of the hourly data points of outdoor ventilation around and inside buildings. dry bulb temperature and relative humidity falling beyond the comfort zone thus experiencing high temperature and • Long and narrow buildings (shallow floor plans) are humidity. Certain periods of the year have the outside more suited to this climate as they provide maximum conditions falling below the comfort zone. The chart ventilation. therefore suggests that natural ventilation, passive heating through direct solar heat gain and solar shading are the • North and south facing walls should have large and most effective strategies for improving thermal comfort. fully openable openings. These openings should preferably be oriented to take advantage of the prevailing breezes to facilitate natural airflow. Bioclimatic recommendations Openings at body level are more effective. The design objectives and responses for Great Lakes climate like Kampala’s should be to address issues due to • Openings should be located on opposite sides of high daily temperatures variation, high relative humidity walls to allow for proper cross-ventilations. Internal and high solar radiation levels. The following passive walls should also have openings for airflow through design strategies may be used to address the cooling and the internal space. heating requirements that result from the above climatic characteristics: • It is advisable to have permanent vents / openings close to the ceiling / roof to prevent the built up of a. To provide maximum protection against hot air and encourage thermal air movement. direct and indirect solar radiation • Ventilated double roofs enhance ventilation of the • Buildings should be oriented with their long axis roof minimising overheating. running east – west to provide effective shading. c. Enabling passive heating • Openings should be located on the north and south facing façades and avoided on the east and west • Medium weight walls, floors and ceilings are facing façades to reduce heat gain from the low early recommended to explore passive solar gains by morning and late afternoon sun. storing heat accumulated during the day (avoiding overheating) to balance the night time low • Appropriate shading devices should be located on temperatures to keep them at comfort level. all openings. These can be in form of extended roof eaves, vertical fins, covered verandas and porches • Excessive glazing should be avoided as it can lead etc. (Figure 291). to overheating during the hot period as well as lead to extensive heat loss at night or during the cold • Additional solar radiation protection may be provided periods. by shade-providing vegetation within the space surrounding the building. • All windows should be airtight to prevent heat losses when the outdoor temperatures are below the • Reflective roof surfaces and light coloured external comfort zone. finishes are appropriate to reflect solar radiation and minimise heat gains. 172 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 291 Provision of perforated screen walls and openable windows aid in cross Ventilation. WIndows are shaded keeping out solar radiation thus providing cool interiors.

British High Commission building in Kampala Source: https://www.kilburnnightingale.com / © Richard NIGHTINGALE EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 173 BIOCLIMATIC ARCHITECTURAL DESIGN

6.3 RWANDA

Figure 292 Map of Africa showing the location of RWANDA

Source: http://www.d-maps.com/ 174 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

table 33 Representative towns in RWANDA

CITY/TOWN ALTITUDE (M) LATITUDE LONGITUDE CLIMATE ZONE

Butare 1,768 m 2° 36’ S 29° 45’ E Zone 5 – Upland Gisenyi 1,481 m 1° 41’ S 29° 15’ E Zone 5 – Upland Kigali 1,567 m 1° 56’ S 30° 03’ E Zone 5 – Upland Kibuye 1,500 m 2° 03’ S 30° 04’ E Zone 5 – Upland Ruhengeri 1,860 m 1° 30’ S 29° 63’ E Zone 5 – Upland Rwamagana 1,528 m 1° 57’ S 30° 26’ E Zone 5 – Upland EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 175 BIOCLIMATIC ARCHITECTURAL DESIGN

KIGALI

Figure 293 Location of Kigali Climatic Zone UPLAND Latitude 01° 56’ S Longitude 30° 03’ E Altitude 1,567 m

Figure 294 Aerial view of Kigali city

Figure 295 Location of Kigali city

GEOGRAPHY AND bioclimatic data occurring in April. Relative humidity ranges at 67 – 81% throughout the year while the wind velocity averages at Kigali, the capital and largest city in Rwanda, is located at 5.1 m/s with the predominant wind direction being South geographic coordinates 01° 56’ S, 30° 03’ E. At an altitude East. The annual average global solar radiation in Kigali is of 1,567 m above sea level, the city enjoys a pleasant 5.0 kWh/m2. upland climate with annual average temperature of 21 °C. March and October are the warmest months on average while June is the coolest month. The average annual rainfall is recorded at 951 mm with the highest amount

table 34 Kigali monthly mean climatic data table

Month Dry bulb Relative Wind Global solar Direct Diffuse solar Rainfall [mm] temp [°C] humidity [%] velocity [m/s] radiation normal solar radiation [kWh/m2 day] radiation [kWh/m2 day] [kWh/m2 day] JAN 21.1 75.0 6.2 4.9 3.7 2.5 76.9 FEB 21.2 77.0 6.2 5.0 3.6 2.5 91 MAR 21.4 78.0 6.2 5.1 3.7 2.5 114.2 APR 20.9 81.0 5.1 4.9 3.5 2.4 154.2 MAY 21.1 78.0 4.1 4.9 3.9 2.3 88.1 JUN 20.3 75.0 3.6 5.1 4.4 2.0 18.6 JUL 20.8 67.0 3.1 5.2 5.0 1.9 11.4 AUG 21.3 67.0 3.6 5.1 4.3 2.1 31.1 SEP 21.3 73.0 5.1 5.0 3.4 2.5 69.6 OCT 21.5 75.0 5.7 4.9 3.6 2.3 105.7 NOV 20.4 81.0 5.7 4.8 3.3 2.5 112.7 DEC 20.8 78.0 6.2 4.7 3.5 2.5 77.4

Figure 296 Monthly mean maximum and minimum temperature for Kigali T-MiN T-MAX Kigali 40 35 30 27.2 27 27.1 26.9 26.5 25.6 26 25.4 26.1 26.5 25.5 26.2 25 C]

° 20 16.3 16.5 16.4 16.4 [ 15.7 15.2 16.1 15.4 15.7 15.8 15.4 15.7 15 10 5 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 297 Monthly mean relative humidity for Kigali rH-MiN rH-MAX Kigali 97 97 93 96 96 95 95 93 94 95 100 89 85 80 65 64 60 56 57 59 56 58 60 52 54 47 47 [%] 40

0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 177 BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 298 Monthly average rainfall for Kigali

rAiNFALL Kigali 350 300 250 200 154.2

[mm] 150 114.2 105.7 112.7 91 88.1 100 76.9 69.6 77.4 31.1 50 18.6 11.4 0 JAN FEB MAr APr MAY JuN JuL AuG SEP OCT NOV DEC

Figure 299 Polar sun path diagram for Latitude 1° South 178 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

Figure 300 Wind rose diagram showing the prevailing wind direction in Kigali

Figure 301 Psychrometric chart with passive design strategies overlays for Kigali

Interpretation • Large windows should be avoided on the east and west facing façades. In Kigali, most of the hourly points of outdoor dry bulb temperature and relative humidity fall within the comfort • Appropriate sun shading devices should be zone. However, a substantial portion falls below the incorporated to keep out the solar radiation and comfort zone as seen in Figure 301. This means that during glare during certain hours of the day during the hot that period, space heating is necessary to extend the limit periods. of comfort zone. This can be done through passive heating through direct solar heat gain and thermal mass. Further, b. Enabling passive heating internal heat gain from equipment, lights and occupants are also helpful in extending the thermal comfort and reducing • Careful orientation of buildings with main rooms heating demand. However, during certain times of the year, facing north east is appropriate to allow a certain the hourly data points (outdoor dry bulb temperature and amount of solar radiation to penetrate for passive relative humidity) fall beyond the comfort zone. Thermal heating during the cold periods. mass is effective in extending the comfort zone by absorbing and storing daytime solar heat for release at night when • The floor plan should be organised such that it the temperatures fall below the comfort zone. Natural allows the sun to penetrate daytime spaces during ventilation is also effective in creating thermal comfort in the cold periods. periods of high temperature and high relative humidity. • Compact forms reduce heat gains during the hot periods and minimise heat losses during the cold Bioclimatic recommendations periods. According to the climatic data for Kigali, the following design strategies are recommended for: • Medium weight walls, floors and ceilings are recommended to explore passive heating by a. Protection against heat gain in the hot storing heat accumulated during the day (avoiding period overheating) to balance the night time low temperatures to keep them at comfort level. • Buildings should be oriented with the main glazed windows facing north and south for easier sun • Excessive glazing should be avoided as it can lead to control and to minimise overheating during the hot overheating during the hot periods.

Figure 302 Deep overhangs to the north and south provide shading against solar radiation in turn assisting in cooling of the interior spaces. These overhangs also provide shading to outdoor spaces.

Kimisagara Football for Hope Centre, Kigali Source: http://www.archdaily.com/267440/kimisagara-football-for-hope-centre-kdap / Architectural Field Office with Architecture for Humanity © Killian DOHERTY 180 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

• period as well as lead to extensive heat loss at night • Additional heating systems such as fireplaces can be or during the cold periods. incorporated in the design.

Figure 303 High level openings have been incorporated to facilitate natural cross ventilation oF rooms as well as provision of daylighting.

Kimisagara Football for Hope Centre, Kigali Source: http://www.archdaily.com/267440/kimisagara-football-for-hope-centre-kdap / Architectural Field Office with Architecture for Humanity © Killian DOHERTY EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 181 BIOCLIMATIC ARCHITECTURAL DESIGN

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APPENDIX 01- mahoney tables*

TABLE 1: DATA COLLECTION Location Latitude Longitude Altitude AIR TEMPERATURE 0C J F M A M J J A S O N D High AMT Monthly mean max. Monthly mean min. Monthly mean range Low AMR RELATIVE HUMIDITY % Monthly mean max. (am) Monthly mean min (pm) Average Humidity group

Humidity group 1 If average RH - below 30% Note 2 30- 50% 3 50- 70% 4 Above 70%

RAIN AND WIND J F M A M J J A S O N D Total Rainfall, mm Wind, prevailing Wind, secondary AMT = Annual Mean Temperature AMR = Annual Mean Range TABLE 2: TEMPERATURE AND HUMIDITY DIAGNOSIS AMT over 200C AMT 15- 200C AMT below 200C Comfort limit Day Night Day Night Day Night Humidity group 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

RAIN AND WIND J F M A M J J A S O N D AMT Monthly mean. max. 0C Day comfort Upper Lower Monthly mean. min. 0C Night com- Upper fort Lower Thermal Day value O,H,C stress Night * The Mahoney tables presented in this section are adopted from a reproduction by Anh Tuan NGUYEN (2013) – University of Liege Belgium. Source: http://www.mediafire.com/file/85jh7lhq56coqsw/Mahoney+Tables.xlsx 184 EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR BIOCLIMATIC ARCHITECTURAL DESIGN

H (hot): if mean is above comfort limits O (comfort): if mean is within comfort limits C (cold): if mean is below comfort limits INDICATORS Applicable when: Indicator Thermal Stress Rainfall Humidity Monthly mean range group AMR Meaning Day Night Air movement essential H1 H 4 H 2,3 Less than 100C Air movement desirable H2 O 4 Rain protection neccessary H3 Over 200mm Thermal capacity necessary A1 1,2,3 More than 100C Outdoor sleeping desirable A2 H 1,2 H O 1,2 More than 100C Protection from cold A3 C

INDICATORS J F M A M J J A S O N D Total Humid: H1 H2 H3 Arid A1 A2 A3 TABLE 3: RECOMMENDED SPECIFICATIONS

Indicator totals from Table 2 H1 H2 H3 A1 A2 A3

Layout 0- 1 1 Orientation North and South (long axis East- West) 11,12 5- 12 0- 4 2 Compact courtyard planning Spacing 11,12 3 Opening spacing for breeze penetration 2- 10 4 0,1 5 Compact courtyard planning Air movement 3- 12 6 Room single banked, permanent provision of air 1,2 0- 5 movement 6- 12 7 Double banked room, temporary provision for air 0 2- 12 movement 0- 1 8 No air movement Openings 0,1 0 9 Large openings, 40- 80% 11,12 0,1 10 Very small openings, 10- 20% Any other conditions 11 Medium openings, 20- 40% EAST AFRICA CLIMATIC DATA AND GUIDELINES FOR 185 BIOCLIMATIC ARCHITECTURAL DESIGN

Walls 0- 2 0 12 Light walls, short time lag 3- 12 0,1 13 Heavy external and internal walls Roofs 0- 5 14 Light, insulated roofs 6- 12 15 Heavy roofs, over 8h time lag Outdoor sleeping 2- 12 16 Space for outdoor sleeping required Rain protection 3 - 12 17 Protection from heavy rain necessary TABLE 4: DETAIL RECOMMENDATIONS

Indicator totals from Table 2 H1 H2 H3 A1 A2 A3

Size of openings 0,1 0 1 Large 40- 80% 1- 12 2 Medium 25- 40% 2- 5 6- 10 3 Small 15- 25% 11,12 0- 3 4 Very small 10-20% 4- 12 5 Medium 25- 40% Position of openings 3- 12 6 In North and South walls at body height on windwad 1- 2 0- 5 6- 12 7 As above, openings also in internal walls 0 2- 12 Protection of openings 0- 2 8 Exclude direct sunlight 2- 12 9 Provide protection from rain Walls and floors 0- 2 10 Light, low thermal capacity 2- 12 11 Heavy, over 8h time lag Roofs 10- 12 0- 2 12 Light, reflective surface, capacity 3- 12 13 Light, well insulated 0- 9 0- 5 6- 12 14 Heavy, over 8h time lag External surfaces 1- 12 15 Space for outdoor sleeping 1- 12 16 Adequate rainwater drainage SUSTAINABLE BUILDING DESIGN FOR TROPICAL CLIMATES PRINCIPLES AND APPLICATIONS FOR EASTERN AFRICA www.unhabitat.org (UN-Habitat) Human Settlements Programme Nations United GPO KENYA 30030, 00100 Nairobi Box O. P. Office) 254-020-7623120 (Central Tel: “Promoting Energy Efficiency in Buildings in East Africa” in Buildings Energy Efficiency “Promoting The project Nations in collaboration with the United is an initiative of UN-Habitat Facility (GEF) Environment (UNEP), the Global Programme Environment Rwanda and Burundi. and the governments of Kenya, Uganda, Tanzania,