Keyhole House by Crawford Partnership
The greenest houses are built on the brownest sites, using land that would otherwise go to waste. Crawford Partnership in London has designed the Keyhole house on a "backland" (backyard building-behind-a-building) property by a railway, accessible only through an "undercroft" passage between neighbouring houses. It is built of heavy timber with prefabricated floor, wall and roof panels, and covered in western cedar.
From the street there is only a glass door filling in the passage to the rear.
The house is designed to have a low environmental impact. To the south large triple glazed soundproof full height windows allow plentiful light into the interior and can be controlled with external copper mesh shutters to balance solar gain.
A green roof ‘sedum’ reduces water run off while improving insulation values and a grey water recycling system reduces water use. A ground source heat pump provides much of the energy for the heating system with high efficiency, low temperature, under floor heating utilised throughout combined with solar hot water heating. Photovoltaic panels also supplement the energy demand.