This pair of 3 bedroom houses scored an EcoHomes ‘Excellent’ rating at a construction cost barely higher than standard social housing.  We achieved this using a prefabricated timber frame clad with timber and a thin render system to avoid ‘wet trades’ and reduce the construction period.  This also allowed us to super insulate the walls without making them any thicker than traditional construction.  The houses were designed to minimise heat loss through their compact shape, draught lobbies and reduced openings on the north side.  Free solar gain was optimised by increasing the glazed area on the south elevation and protecting it from overheating in summer with solar shades.  We also incorporated a shared rainwater harvesting system as the most cost effective ‘add on’ sustainable technology.