The term ‘plus energy building’ is not an official term used by the European Commission. It generally means a building with an energy performance that is so good, that the energy generated by the building is higher than the energy used by the building. This energy balance is mostly done on an annual basis. The energy generated often comes from photovoltaic panels or micro-wind generators. Since the spaces for mounting the photovoltaic panels or the wind generators are often limited and the technologies cause investment costs, the building envelope and building services systems of plus energy buildings are in general of a high quality as well. Thus the energy use of the building to be balanced with generated energy is low. Please note: plus energy can relate to all energy used by the building or only some of the energy uses (heating, domestic hot water, cooling, ventilation, lighting, plug loads) and to delivered or primary energy. Germany for example has a promotion programme for plus energy houses that is based on a detailed definition of how to assess the plus energy level.