• Staying in closed rooms we consume oxigene by breathing. We produce CO2 and humidity.


  • The decreasing amount of oxigene and the increasing amount of CO2 have different effects on humans. We loose the ability to concentrate, we become tired, even headaches can be caused.

  • When there are two persons (sleeping or sitting) more then 2 hours in a room with closed windows, the air is getting very insufficient. A controlled ventilation system holds the air quality constantly in a pleasant range.
    (source: VEW; room with 40 mē)


  • Humans produce humidity by cooking, showering, bathing but also by sweating. If this humidity is not taken out, it falls out on cold surfaces like walls what could cause fungus to grow.


  • The usual free ventilation due to leaking windowseems, is reduced by modernisation and rebuilding with new tight closing windows. In new buildings with new windows you dont have free ventilation.


  • Ventilating regulary - every two hours rush ventilation - is hard to maintain. It has also some disadvantages: To ventilate the apartement completely, you have to leave the windows open for a quite long time. This is accompanied by a serious draft effect, in the office this can cause a paper storm. In addition this form of ventilation leads to an instable airquality.


  • During winter the fresh air from outside is cold so that it is unpleasent to ventilate, because of the down cooling of the rooms.


  • With a controlled ventilation you get a steady room air. Fresh air is brought to every corner of the room.


  • There is no unsteady air quality, because the old air is changed constantly against fresh air.


  • With a heat recovery at the used old room air that is still warm, the fresh air from outside can be warmed up. Like this you get warm fresh air into your room even in winter.