context: in 1994, President Mandela launched a mass housing initiative for South Africa. With an ambitious target of nearly one million new low-cost houses by 1999, government subsidies have resulted in approximately 780,000 new houses. The reality, however, is that most of these houses are poorly constructed and poorly insulated. This type of housing significantly affects the health, productivity, safety, comfort and income of its residents. The development of the Soweto ECOTM (Energy Cost Optimised) House was a call to change these poor housing prospects and to increase the number of sustainable homes in South Africa’s low-income housing sector.
what: conceived as a technology demonstration and a teaching resource, the Soweto ECOTM House is the first fully energy saving house to be built in Soweto (Johannesburg, South Africa). The house achieves natural thermal comfort for its residents, reducing energy consumption and the need to burn fossil fuels or consume large amounts of electricity. The project was showcased on the occasion of the World Summit on Sustainable Development (WSSD) held in 2002 in Johannesburg.
why: conceived by PEER Africa, an energy efficiency company, the University of the Witwatersrand (WITS) and IIEC-Africa (an international environmental NGO), the project forms part of the larger WITS Soweto Clean Air Monitoring Project. The house will serve as a model home for monitoring and measurement purposes and will also serve as a demonstration house for energy efficiency. To succeed in building such a house, the project team paid close attention to the design of the building envelope and the fitting of all relevant energy efficiency technologies, as well as water conservation and energy efficient water heating practices. Furthermore, it serves as a test house for an air-quality monitoring project in Soweto and hopefully will pave the way towards a massive scale application of energy saving principles in public housing schemes
how: to give you an idea on how an energy saving house is made, here are some of the Soweto project’s features:
results: in this context, energy efficiency is not conceived as a goal in itself, but as a design approach with a wide range of benefits:
- passive solar design is employed by orienting the house so that the main rooms face north to maximise solar radiation for heating and cooling the house during different seasons. The northern exposed windows have large panes to allow maximum sun penetration during the winter and a 600mm roof overhang on the same side to shield the windows from direct radiation during the summer;
- energy efficiency: the building envelope is made of brick walling skins with polystyrene insulation placed against the inner skin wall. The floor in the main living areas is finished with dark ceramic tiles for enhanced thermal storage. Light coloured roof tiles were used as they reflect the intense heat of the summer. Polystyrene was used to insulate the ceiling;
- the house also uses energy efficient compact fluorescent lights (CFL). These light fittings give more light but less heat than the conventional light bulbs, consume less energy and last longer. The hot water heater, stove and fridge are energy star rated to reduce electric power consumption;
- rainwater harvesting: the house integrates a rainwater-harvesting system for washing clothes and gardening. Spending on water is reduced and conservation of a scarce resource is achieved.
- savings to the home-owner: energy efficient low-cost houses require approximately 70% less energy than conventionally built homes, thus saving on energy expenses.
- safety: consider a house using 70% less energy. In a non-electrified house that means less burning of fossil fuels and bio-gasses for heating, cooking and entertainment. Ultimately it reduces emissions and the release of toxins into the air.
- reduction in fossil fuel use for thermal benefits: communities have a common practice of burning coal in ‘mbawulas’ (braziers) for space heating and entertainment inside shacks and even in RDP housing. This burning of fossil fuels releases toxic gasses into the house, which contributes to lung, eye and skin irritations and accidental burns. The natural thermal comfort of energy efficient houses dispels the need to burn fossil fuels indoors.
- global greenhouse gas mitigation: an energy efficient house brings an anticipated carbon dioxide saving (from coal and paraffin) of approximately 776,800 kg/annum per 2,300 houses. If similar savings were achieved in the almost 6,500 houses affected through the Green Professionals scheme, the overall carbon dioxide savings would come to more than 2,000 tons per year.