Much has been made of the role of airlines and oil companies in the fight against climate change, but few think of the built environment. Yet property is thought to account for nearly half of all carbon emissions and about half of those come from commercial buildings. Last year's Intergovernmental Panel on Climate Change report highlighted the construction sector as that with the most potential to reduce greenhouse gas emissions, and in the most cost effective way. In the past, companies building new premises were driven by the desire to be seen as good corporate citizens. Swiss Re, the insurance company, made much of its association with the 30 St Mary Axe building in London