In Freiburg, passive houses like this are relatively few, but energy-saving houses are the norm. Elsewhere in Germany, the law states that every new house built must waste no more than 75kWh/m2 per year (roughly a quarter of the energy lost from a typical Victorian house in Britain) but the specification in Freiburg is radically lower. 'It used to be 65kWh per year,' says Meinhard, 'but we are now discussing a new Freiburg law of 55, 50 or even 40kWh.'