Buildings (both domestic and non-domestic) in EU are responsible for approximately 40% of the primary energy use. This makes buildings the largest 'energy-using-sector' in the Union. From the energy point of view, one can reduce consumption: by using building products that are sustainable (e.g. have little embodied energy), by designing and constructing buildings that use as little energy as possible with respect to heating, cooling, ventilation, etc. and by maintaining and operating buildings without wasting energy.
According to the Dutch Housing Laws an energy performance (EPc) = 1,0 is obliged. The project in Harderwijk achieves a much better energy performance (EPc) = 0,75, the houses in Etten Leur achieves an energy performance (EPc) = 0,50. Passive solar energy, photovoltaic solar energy, co-generation conservatories, thermal power station, sun rooms, solar collectors and heat recovery are applied in these houses.