A government competition has challenged housebuilders to come up with proposals for zero carbon developments.
The second phase of the Design for Manufacture competition, called the Carbon Challenge, is calling for green and affordable housing communities.
However, English Partnerships (EP), which is running the competition, said there would be no upper cost limit as it did not yet know how much the green homes would cost.
Developments will have to meet at least level 5 of the Code for Sustainable Homes, which stipulates zero carbon emissions for elements controlled by the Building Regulations. They will also have to comply with the planning policy statement on climate change.
EP has already brought forward two sites for the competition – Hanham Hall near Bristol and Glebe Road in Peterborough.
The agency is calling for the public and private sectors to provide further sites. It is expected that in the first year of the competition five sites will be identified.
The successful bidders for the first two sites will be announced in autumn 2007 and work will start on site in 2008.