Barratt Green House claims to meet level six criteria

Level six status means it will emit zero carbon over a year and so will qualify for zero stamp duty. The three-bed house, designed by architect Gaunt Francis, is constructed from concrete wall panels and pre-cast concrete floor slabs with a grass roof. It has an air-source heat pump, solar hot water panels and photovoltaic panels, and uses rainwater harvesting. The house is at the BRE Innovation Park at Watford.