Saving heating costs by means of heat recovery
The air discharged from every house contains a great deal of energy. In winter it is considerably warmer than the outside air and additionally contains steam from which heat can be extracted by means of 
condensation. At the same time the cold outside air blown in during airing must first be heated up by the heating system.
From this observation a simple but at the same time ingenious idea was born: the principle of heat recovery. We use the energy stored in the warm, humid air ("exhaust air"), e.g. from the kitchen, bathroom, WC, to preheat the cold "outside air". It is supplied as "supply air" to the common rooms, such as living room, bedrooms, childrens rooms and workrooms. No odours or pollution are exchanged at all in the process, since the air currents are always separated in the heat exchanger of the ventilation unit. Heat provision levels of up to 95% (with condensate) can be achieved with this technology; the recovered heat is more than 15 times higher than the electrical power required to drive the fans.