The Daikin Air Conditioning System exchanges heat, reducing the energy consumption of the air conditioning system, with the ability in mid-season for the ventilation system to work independently and thus replace the air conditioning system. The exchange in heat reduces the energy consumption of the air conditioning system. The unit can work in two modes: Firstly in the total heat exchange mode the ventilator exchanges the heat between the exhaust air (from indoor) and the supply air (from outdoor) by means of a heat exchange element. This avoids cold draught when the outdoor air is colder than the indoor air and secondly in the bypass mode the ventilator will not exchange heat between exhaust and supply air by means of bypassing the heat exchange element. The outdoor air is brought directly into the room.