The most complete ventilation system is the balanced ventilation system with heat recovery.
In a supply and exhaust air system with heat recovery the outdoor air vents are positioned in living rooms and bedrooms and the exhaust air vents in the bathroom, toilet and utility room. This system makes use of the heat in the used ventilation air, air that would otherwise be released straight out into the cold. The heated indoor air passes through a heat recovery unit before being expelled and is used to heat the incoming outdoor air. This saves energy while providing a better climate indoors. This makes it possible to control the air quality and the air volume coming into the home.