Creating more environmentally friendly buildings represents the most effective way to cut North America's greenhouse gas emissions, according to a new report from Canada's Commission for Environmental Co-operation.

The report, Green Building in North America: Opportunities and Challenges, says that North America's buildings contribute just over a third of the region's greenhouse gas emissions.

The region currently emits 2,200 megatons per year of carbon dioxide. Continuing current development patterns would add another 845 megatons of carbon dioxide per year into the atmosphere in 2030.

Conversely, the report argued that under the most aggressive mitigation scenario where developers adopt cutting-edge technologies to improve the energy efficiency of the building stock, the region would produce 1,700 megatons of carbon dioxide emissions per year in 2030, effectively cutting current emissions by 38 per cent.

The CEC report warned that focusing on constructing new green buildings, as is currently the case in several countries including the UK, would fail to deliver the required levels of carbon savings.

"The lion's share of the emissions that come from buildings come from existing buildings, so the notion of new construction getting us out of the challenge we're facing is a bit of a red herring," said Helen Goodland executive director of the Light House [www.sustainablebuildingcentre.com], an advocacy group for sustainable buildings in Canada.

However, she added that innovative legislation and energy tariffs were needed both to create rewards for the retrofitting of existing structures with energy-efficient measures, and to persuade developers of new buildings to embrace sustainable design principles.

The CEC study is the latest in a series of studies arguing that improvements new and existing buildings represent the quickest and most cost effective means of cutting carbon emissions.

A recent report by the United Nations Environment Programme also highlighted the importance of sustainable building as a drive for climate change last year, as did a report from the International Panel on Climate Change called Mitigating Climate Change.