DHV Architects in Bristol have prepared the construction package for a new build 220m² Passivhaus dwelling near Salisbury. The construction is a timber frame with 300mm twin-stud walls fully filled with mineral wool insulation; the reinforced concrete slab is cast over 300mm of polystyrene insulation. The U-values of walls, floor and roof typically average 0.15 W/m². All construction junctions have been drawn up at large scale to design out cold bridging and specify the airtightness strategy.