Whereas as Bedzed has a radical organisation – five parallel extrusions of three-storey buildings separated by canyon-like alleyways – its neighbour is a formless scatter of two-storey brick boxes.
Bill Dunster Architects, the practice behind Bedzed, arranged these five rows to take maximum advantage of passive solar energy. All 60 dwellings sport generous south-facing conservatories, but instead of projecting into the rear gardens, these form three-storey glazed lobbies to the front doors. Rooms in the maisonettes on the ground and first floor and the studio flats above are all flooded with the sun's heat and light.
All the dwellings have gardens but, not in the suburban sense: instead, two levels of roof gardens are stepped up the rear of the houses. And rather than being interrupted by spindly central-heating flues, the rooftops culminate in sculptural double cowls that swallow fresh air on one side and breathe out used air on the other, with a heat exchanger transferring waste heat from the latter to the former.
Facing materials are brickwork and untreated oak boarding, and the construction is the antithesis of a slimline timber frame – it is a combination of massive brick-and-block walls and exposed concrete floor slabs that serve as heat sinks. Wall cavities are a yawning 300 mm wide and are stuffed with mineral-fibre thermal insulation. What is more, instead of installing individual boilers in each dwelling, the entire scheme is supplied by a communal combined heat and power plant.
The combination of solar gain, heat sink, high insulation, controlled ventilation and the CHP plant will enable Bedzed householders to save £500 a year in energy bills. Amazingly, the only radiators in the three-bedroom maisonettes are two tiny panels in the hallway.
Sustainability is about conserving land, materials and energy, and this is where Bedzed's abundance of green features really comes into its own. The site is part of a former sewage plant and the high-density layout of 187 residents per hectare exploits it to maximum efficiency. The renewable and recycled building materials used include structural steelwork, timber internal doors and aggregate from crushed concrete. Even the fuel for the CHP plant will be provided by tree cuttings from London's parks, helping the estate to produce as much energy over the yearly cycle as it draws from the national grid.
Sustainability is also about lifestyles, and Bedzed provides workspaces at the same density as the housing, so that residents can work from home.
Even before the showflats open tomorrow, more than 300 people have registered an interest in buying or renting. As Susan Viner, project architect of Bill Dunster Architects, says: "We have tapped into the general feeling of people who want to play their part in saving the planet. Volume housebuilders are so far behind the public mood."
Gardiner & Theobald is construction manager and QS, Ellis & Moore is structural engineer, Arup is services engineer and Bioregional Development Group is sustainability consultant.