It stores heat from its kitchen and bathroom and redistributes it to living spaces. Its south-facing wall traps and stores heat from the sun, releasing it slowly inside. It stores hot water underground during the summer and releases it to provide heat in the winter. So it doesn't need conventional central heating. Unsurprisingly, the house meets level five of six-level building standard the code for sustainable homes.
It was opened by Downton Abbey star Hugh Bonneville, with a free hog roast, all of which might help explain the excitement. But there was more to it than that - a lot more. For the house, and a next-door 106-year-old fire station converted into an eco-centre for the community, mark the launch of Whitehill Bordon eco-town - one of only four surviving from the previous government's initiative - with the start of serious eco-building.
The history of the existing settlement around which the eco-town will be based is exotic. It was created by the Ministry of Defence to house Royal Engineers and their families out in East Hampshire as part of a vast military complex in the area. It's still bordered by huge chunks of forest shown on Ordnance Survey maps as "danger areas". Only when the sappers depart in 2015 will the shells and landmines go. The existing housing is standard army issue, but set in an extraordinary sylvan environment with generous parks and playing fields and public buildings.
And it's a ready-made garden city, such as Ebenezer Howard might have imagined in 1898. It's 43 miles from London and 35 miles from Letchworth. It has a target population of 24,000. Howard imagined 32,000 for Letchworth. It's surrounded by green belt - including part of the South Downs national park - just as Howard imagined it in his legendary diagram. And its isolation protects it from becoming just another commuter suburb.
So it's exactly what the Town and Country Planning Association has been promoting since Howard founded it, and David Cameron is now - somewhat surprisingly - extolling. Third garden city, first eco-town: a wonderful start for a second life.
Sir Peter Hall is Bartlett professor of planning and regeneration, University College London, and president of the Town and Country Planning Association