Proper ventilation

CO2 monitor traffic light display
© Fraunhofer WKI | Erik Uhde

The air quality indoors is usually no better than outdoors, so outdoor air quality can also have an impact on indoor air quality. In enclosed spaces, human activity or the room itself can increase air pollutants, and without frequent ventilation, the air can quickly become no longer "fresh". If there are many people in a room, it needs to be ventilated more frequently. You can use the CO2 calculator to estimate how often you should ventilate. The so-called CO2 “traffic light” shows the amount of CO2 in the indoor air in an easy-to-understand way and can thus help you to ventilate regularly.

It also makes sense to increase ventilation in newly renovated homes, new buildings or after purchasing new furniture, as emissions from the new materials can make the indoor air quality worse.

At low outdoor temperatures, ventilation is also associated with heat loss, which is why a compromise must be found between sufficient ventilation and energy savings. A brief period of strong ventilation is therefore more effective than continuous weak ventilation.

  • Ventilate several times a day, preferably by opening opposite windows (cross ventilation). In winter, 3 to 5 minutes at a time is sufficient; in summer, at least 10 minutes of ventilation is recommended.
  • After showering or bathing, remove moisture from walls and floors and ventilate thoroughly (wide open windows).
  • When cooking, the moist air should be removed by a kitchen hood or additional ventilation.
  • When heating with wood or coal and when cooking with gas, ensure that there is a sufficient supply of air.
  • Ensure good ventilation during cleaning, repair and handicraft work.

Warmer areas of a home should not be ventilated through cooler rooms - otherwise there is a risk of moisture condensing on the cooler walls. In basements, this effect can lead to damp walls and mold growth in summer. Therefore, basements should not be ventilated during warm, humid summers.