Crawford Partnership has won planning permission for this eco-friendly house in West Hampstead, north London. The London-based practice was given the go-ahead from Camden Council for the 205m² live/work unit, which will be squeezed into a tight plot backing on to a railway line, currently occupied by a semi-derelict, two-storey brick building. To maximise the available built space, the house occupies the entire site, with access to the property limited to a narrow 'undercroft' passage running between neighbouring houses. A green roof, photovoltaic panels, a ground-source heat pump and a greywater recycling system helped Crawford Partnership achieve the low-energy specification of its private client, while the location near a railway line required some design wrangling to meet acoustic and vibration regulations. The project is one of a series of developments by the practice that use derelict backland plots for modern housing. One of these, its Snowden House II scheme in North Kensington, was a finalist in the 2007 AJ Small Projects competition (AJ 18.01.07).