Word has gotten around that it’s better not to open windows for a long time, but rather to open them fully and then air them briefly. This is then called intermittent ventilation or, if you open opposite windows, cross ventilation.
In spring or autumn, a complete air exchange can take 15 to 20 minutes and if you do this three to five times a day, the windows are open for quite a long time. This tactic no longer works in winter because the outside temperatures are too low.
However, it is advisable to air the room just as often, i.e. three to five times a day even when the temperature is below zero. However, three to five minutes with the window open are then sufficient. From this, the 5×5 rule can be derived as a reminder: Translated, this means airing the room five times a day for five minutes.
This is easy to keep on holiday or at the weekend or if you work a lot from home. However, if you are not at home during the day, you need a different strategy. The good news: If you are absent all day, less frequent airing is sufficient. Minimum morning and evening, but it is better to use the 3×5 rule. That means airing the room for five minutes three times a day.
Air out in the morning when you get up from work and again just before you go to bed.
