Regular ventilation is necessary for a healthy and comfortable room climate. How much fresh air is needed depends on the number of persons who use a room and the degree of utilization. Likewise outside temperature plays a role. Too much or incorrect ventilation (e.g., continuous ventilation with a tipped window) unnecessarily wastes energy. A mechanical ventilation system can prove more efficient:

• It provides uniform air quality in a room.
• It regulates the intake air quantity based on the fresh air requirement of the persons in the room.
• Simple controlled exhaust systems consist of an exhaust unit and intake valves in the outside walls to provide good air quality.
• To reduce heat loss due to ventilation, a heat exchanger can be installed.

Controlled ventilation

Controlled residential ventilation brings fresh outside air inside via dust filters. Warm exhaust from kitchen, bath, toilet, etc. is fed to a heat exchanger that recovers the heat before it is sent outside. Cold fresh air is taken in, filtered and pre-warmed by the heat exchanger before being blown into the living space. Correctly managed, this is an energy-saving measure.

• Controlled ventilation is used especially in well insulated low-energy homes.
• The prerequisite for controlled ventilation is in any case an air-tight building design.
• Old buildings can seldom meet the strict requirements of air-tightness.
• These are not air conditioning (cooling) units as they simply climatize room air.
• The most modern controlled ventilation systems can be used in transition seasons for tempering room temperatures or for dehumidification.

Options for decentralized air conditioning:

• Mobile air conditioning (fixed connection to outside)
• Compact window-type air conditioning (outside and inside are combined in one compact unit, installed primarily above windows and doors in the outside wall); drawbacks: noise and poor regulation
• Mono-split air conditioning (separate inside and outside units, quiet, comfortable, permanently installed)
• Multi-split air conditioning (multiple inside units, one outside unit, rooms controlled separately)