Proper Airing

When airing during heating, heat loss can not be completely avoided, however it can be limited. This works best with short intensive airing: for this purpose windows and doors should be wide open to try and create a draft. After approximately five to ten minutes the used damp air is replaced by fresh air. The advantage of this intermittent ventilation is that the stored warmth remains in the walls and after closing the windows the room air quickly reaches the desired temperature.
You should avoid constant ventilation when heating by always tilting the windows. Because the warm interior air goes outward in such a way that the heating energy need is increased unnecessarily. In addition only a comparatively small amount of air exchange takes place with tilted windows, so that after one hour a third of the room air still consists of old used air.
Some hints:

Air two to three times daily. A window opened widely two to three minutes in the winter is sufficient and up to ten minutes in the transition period. Important: Close the radiator valve Steamed-up windows are always a signal to air. Water vapour which develops during cooking or showering should be let out immediately by opening the windows.

Living rooms are not good drying places for your laundry because the air humidity increases.

Also unheated rooms should not be continuously ventilated when heating. The rooms cool down completely and the warmth from the walls of heated neighbouring rooms are additionally lost