#Sustainability: Green Building design strategies in East Africa

#Sustainability: Green Building design strategies in East Africa

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By Kimeu Musau

The LRC
Cross ventilation through the LRC Library

Since the mid 1980’s, towns in East Africa have see a rise in construction of heavily air conditioned glass cladded buildings which were originally mostly developed in the temperate climates of the northern hemisphere, in particular Europe and North America.

These glass buildings are now proving to be uneconomical even in Europe, and the cooling loads they generate in the tropics are ridiculously wasteful.

We must realise that the importance of environmentally friendly buildings has never been more central to both the economic and environmental welfare of the East Africa countries.

Governments should take the leading role to facilitate and encourage best environmental practice.

All new government buildings should be environmentally friendly and should be good case studies for “green” building principles. The governments could give tax rebates as incentive to developers of green buildings or offer cash incentives to green building developers as is the case in Malaysia as well as enact legislation and put in place policies on green building practice.

The banking sector too should join in by offering incentives in the form of lower interest rates to developers of green buildings. This will go a long way in creating the right atmosphere to spur sustainable building boom in the region.

UN-Habitat, AAK and other like minded organisations should actively take a leading role in educating the East African people why building green is the only way out of the environmental crisis being witnessed today.

Leading architectural practices in the region should be at the forefront in designing environmentally friendly buildings.

Architectural programs and curriculae in our local Schools of Architecture should also put emphasis on Sustainable Architecture.

In East Africa, there has been no pressure to achieve meaningful construction of green buildings. Nearly everyone has failed to lead in this front and what we have witnessed is sporadic individual efforts. The region needs to pursue a systematic strategy of using sustainable building techniques.

In order to actively promote and implement sustainable building construction in the region, it is important to understand what building green entails. Below is an illustrated check-list of green building design strategies that should be included in any project so as to achieve sustainable or environmentally conscious buildings. Selective application of a few of the strategies will not result in a green building.

Green building design strategies; For prevention of heat gain and provision of cooling, apply the first nine strategies

  1. Buildings orientation: Design your buildings such that the long axis is along the East-West axis.
  2. Design buildings that are narrow in plan. This helps to achieve maximum natural lighting penetration into the buildings and also good cross – ventilation. In situations where a narrow building plan is not achievable, courtyards and atria could be used to aid in provision of natural lighting and.
  3. Sun-shade all glazed areas. This should be realised by use of vertical and horizontal sun-shading elements, deep roof overhangs, balconies, perforated timber screens etc.
  4. Use natural ventilation to provide cooling. This should be elaborately done throughout the building using operable windows, thermal chimneys, metal/timber louvred fenestrations etc.
  5. Use high thermal mass on walls (thick walls). All external walls should be at least 200mm thick.
  6. Place window openings on the North and South facing walls as they receive less solar radiation.
  7. Locate building services (like lifts, lobbies, toilets, stores, ducts etc) on the East and West facing facades to act as heat buffers from strong solar radiation.
  8. Have minimal window openings. It is recommended that all buildings located within the tropics, the East African countries included should have minimal window openings. Fully glazed buildings are not recommended for tropical climates. If glass cladded buildings are built within the tropics, then all the glass must be fully sun-shaded against direct sun shine throughout the day.
  9. Use external finishes that are smooth and light coloured to reduce solar heat absorption e.g. roof cover consisting of brilliant white coloured g.c.i or aluminium-zinc sheets etc
  10. Choice of materials – Your building should use locally available materials, with low embodied energy, with none or minimal maintenance, materials that are sustainably harvested, non-toxic, those with minimal internal pollution and damage to health and those which are easy to re-cycle or to re-use.
  11. Renewable energy – Every building should generate and use renewable energy to power its operations. The target should be a net zero energy (carbon neutral) building that is capable of generating enough green energy to meet all its energy demands during the day and at night. Here several strategies could be employed like Use of solar power, Use of wind energy to generate electricity and Use of biogas produced from the biodegradable waste generated within the project, especially projects in the outskirts of urban areas and rural based projects e.g. waste from farm produce and also from toilet waste.
  12. Rainwater harvesting – Rainwater should be harvested from the building roofs and its water used for cleaning, flushing toilets and watering plants etc.
  13. Sanitation – Use environmentally friendly toilets and sewerage system e.g. bio-digesters, oxidation ponds etc. Toilet waste from the project can be used to produce biogas for cooking and manure. Waste water from wash hand basins (WHBs) and showers can be treated and reused as grey water in flushing of toilets. Sanitary fittings that are water efficient e.g. waterless urinals taps with proximity sensors should be encouraged to reduce water consumption.
  14. Solid waste management – The solid waste generated within the project should be sorted out and the biodegradable waste used to produce biogas whereas the non-biodegradable waste is recycled.
  15. Landscaping – The proposed developments should be landscaped with well-chosen native trees and shrubs etc that require minimal irrigation using portable water.

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