Case study Uganda
Solar control and daylight
The strong equatorial sun has a huge impact on thermal comfort. An important part of our design is the control of solar gain. A generous roof overhang blocks out high sun, and recessed north and south- facing windows keep direct early morning sun out of the building. Tin is favoured over thatched roofs because of a better resistance to rainy season weather, but the re- radiation of incident solar energy into the space is a significant problem. To isolate the space from the hot tin roof we have an insulated ceiling void with high and low level openings which, combined with the mono- pitch roof, function as a solar chimney. This ‘solar roof’ drives airflow through the cavity and
acts as conveyer belt for the solar gain, removing it from the space. The school has no artificial lighting, so natural daylight is critical. A narrow-plan form with tall single- sided windows, clerestory openings (a high wall with a band of narrow windows along the very top) and large doors that can be left open to provide a good distribution of daylight.
Ventilation
The classrooms have occupancy densities double that of the UK norm, so ventilation is critical. The classroom will have high- and low-level openings on opposite sides of the room to increase ventilation.
Acoustics
Acoustics are important in any classroom. Brick, concrete and metal are all hard surfaces with long reverberation times. Hiding these with the wooden ceiling and cob render will reduce reverberation in the classroom.
Community
Construction provides the opportunity for the
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The walls comprise a hybrid of interlocking stablilised soil bricks and a thick internal adobe render that can be made at little cost.
community to learn new skills – specifically the use of the ISSB brick machine. About 150 community members have pledged their support and will volunteer 25,000 hours of labour, making 35,000 bricks over the coming months. Half of the world’s emissions over the next decade
are expected to come from emerging and developing countries. In Africa, like any other country, the building industry is the largest cause of deforestation and environmental pollution. To quote Our Common Future: ‘We must meet the needs of the present without compromising the ability of future generations to meet their own needs.’ l
WEB LINKS
buildingtomorrow.org unhabitat.org
goodearthtrust.org.uk gifford.uk.com
ourcommonfuture.org
The vernacular style of the local villages has informed the design of the planned school.
April 2010 CIBSE Journal
49
JESSICA ROBINSON
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