Visi Sustainable House of the Year 2007
Before the Industrial Revolution most of humankind still understood the delicate symphony of building with relation to the local conditions, one such as the specific climate. Modern technology enabled humankind to forget the nature of the specific climate that they live in.
Although the features of climate (sun, wind, temperature) are beyond our control, the design of the building in relation to the local climate can have a significant effect on the energy consumption of our houses. Bioclimatic design is the process of designing our houses with the relation to their local climate. The aim of this design process is to reduce energy consumption. Although bioclimatic design can be complex process there are logical and simple steps to render lower energy bills and comfortable levels of living.
The single storey dwelling with a view to the south, and solar orientation to the north, is situated on the Johannesburg Highveld. The architects focused their efforts in the design of an environmentally sensitive home for the clients. The walls and landscaped roof blends well in with natural surroundings. The building is simple with ample natural light through clerestory windows, which articulates the interior spaces. No extra adornment was added to the building and simple principles of proportion, space, light, texture, and spatial flow were adhere to.
Most basic principles:
Understand the local climate where the building will be constructed
- i.e. a Karoo house has a vastly different design than a house in Durban.
Always know where the sun is in relation to the building.
Understand which functional spaces can be orientated to the sun for maximum solar gain in winter.
Get the basics right before complicated passive design strategies are employed - i.e. correct orientation and insulation are much more important that photo-voltaic cells on the roof.
Strategies employed in the design:
High thermal mass walls constructed of 200mm concrete blocks, and a concrete roof with 300mm topsoil and lawn will keep the house cool in summer and warm in winter (soil to be added in future).
Small glazing areas, not exceeding 10% floor area will minimize thermal heat loss during the winter.
Good roof insulation prevents thermal heat loss in winter and heat gain in summer.
Save on electricity bills and install a solar hot water geyser- solar power is for free. The heater is situated above the bathroom slab.
Water harvested on the roof of the house is stored in above ground storage tanks, and is utilized for watering indigenous low water usage plants and grasses in the garden. All water is treated by biological septic tank and in turn utilized for garden irrigation.
Fireplaces will provide additional heating during the winter.
Specific care has been taken in design of the windows. Horizontal sun shading north will minimize summer heat gain, and narrow slit windows south will minimize the afternoon southwest solar gain. Northern clerestory windows to the lounge will allow for winter solar heat gain.
Compact design with thermal zoning can minimize space heating in winter. The total house area is only 250 square meters including the double garage.
Material use and construction: The use of appropriate materials such as steel windows, concrete blocks, and s-profile roof sheeting. The walls are constructed of standard concrete block work, and no finishes were applied to the block in the inside or outside. This saves cost and decreases the lifecycle cost.