Buildings are the world's greatest source of CO2 emissions. Even in the USA buildings emit more CO2 than motor vehicles. Much of the CO2 emissions come from the energy required to heat, cool and ventilate buildings, but there are also significant emissions from creating the materials to build and maintain buildings.

This is called embodied energy. There has been considerable amount of study done in New Zealand and Australia, on comparing the CO2 emissions from different building systems. Brian Honey and Andy Buchannan, at Canterbury University, showed in 1992 that there were considerable savings in CO2 emissions by using timber, rather than steel and concrete. Bill Lawson, at the University of New South Wales highlighted the energy efficiency, and reductions in CO2 emissions by using building system based on wood.

Andrew Alcorn at the Centre for Building Research at Victoria University, has produced a set for CO2 emission figures for common building materials. These figures show that softwood can have negative emissions of up to 1,665 g CO2 per kg of wood. This is because wood can store far more CO2 than is emitted from the processing of the wood. CO2 storage in buildings becomes very significant when using German style solid wood buildings designed to last for at least 300 years.

By using Alcorn's CO2 emission figures, the total emissions for a new building can be calculated. These CO2 emissions can be significant, even for a light timber frame building, but when solid wood walls are used, the total emissions can be less than zero. Solid wood walls can elimate athe need for fibreglass or polystyrene insulation, which have high CO2 emissions.

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