Building Biology

People today are becoming increasingly aware of environmental problems and the need for a holistic approach in dealing with them.

However most people’s concern for the environment is focussed on external problems: climate change, depletion of the ozone layer, pollution of air and water. What about the environment in our homes? We spend 80-90% of our lives in buildings. Indoor pollution is residential and commercial buildings through the use of toxic and unhealthy building materials can have a serious effect on our health. Our homes are our third skin (the second being our clothes). The NZ Building Act says clearly we should build energy-efficient and healthy homes. But what about the Building Code? Because of our recent “leaky home scandal” we now have more unhealthy and toxic building material in use such as treated timber, glue, expansion foams and composite boards. These materials give off vapour – formaldehyde is a common one – or absorption can occur through the skin and lungs or through the food chain.

Healthy buildings have passive solar design, good insulation, good ventilation and enough thermal mass to keep temperatures stable, warm in winter, cool in summer. Natural building materials are wood, stone and earth. By using these local materials one can lower the ecological footprint of buildings substantially. The embodied energy (EMERGY) in a building can be very high – as an example there are about 15 litres of oil in a bag of cement. An assessment of energy returned on energy invested (EROEI) is an eye-opener. Cement and some materials are transported long distances. Cement kilns also produce additional carbon dioxide beyond that of the fossil fuels they burn, as a result of converting calcium carbonate to calcium oxide, doubling their global warming impact.

The basic human rights of building your own dwelling and growing your own food are being compromised by red tape and the building industry influencing the building code to fit the available building materials. Long live the kiwi tradition of owner building.
More INFO on healthy buildings from: EBANZ (Earth Building Association of NZ) BRANZ (Building Research Assn NZ), Building Biology Institute NZ www.ecoprojects.co.nz