The future of green building in Britain is tucked at the end of a row of 1930s houses, beside the M1 just north of Watford.

The government wants all new homes in the UK to produce zero net carbon emissions by 2016. But to date, the UK’s leading housebuilders have only completed one house that meets those standards: an experimental three-to-four bedroom home constructed by Barratt at the Building Research Establishment in Garston, Hertfordshire.