Camden Passive House is London's first certified Passivhaus, setting a new benchmark for energy efficient design for the city. The insulated, timber frame structure was built on a tight site and over-shadowing of adjacent buildings had a major impact on the energy balance and design decisions, with PHPP used from the start of the project to determine the optimum position of the house on the site and the optimum percentage and orientation of glazing. Biodiversity was very important for this project which incorporates two wild flower meadow green roofs, a south facing planted garden and an ivy covered gabion stone wall. With the primary objective being to achieve a comfortable home for a young family, whilst minimising energy consumption, the house was designed to use 13kWh/m2/a for heating (a typical new home in the UK is likely to consume nearer 100kWh/m2/a) and annual heating bills are projected to be less than £65 (at standard occupancy maintained at 20 degrees centigrade in winter). This is achieved by high levels of insulation, overall negative psi values, triple glazing, Passivhaus sliding windows, draught free construction, and 92% efficient heat recovery ventilation. Summer comfort is maintained by blinds, natural ventilation, a well insulated structure, and two green roofs. Healthy air and water quality is prioritised by using non-toxic materials, heat recovery ventilation and water filtration for drinking and bathing. Mains water use is supplemented by an underground water harvesting tank providing water for irrigation. All junction details are designed to prevent thermal bridges and the results form part of the Passivhaus Planning Package (PHPP) energy calculations.