Status: 16.01.2024, 19:00 PM
By: Andrea Stettner
CommentsPrint Share
In winter, the risk of mould increases when the walls are too cold and the humidity is too high. We still need to ventilate – but not for too long.
According to the Window + Facade Association (VFF), we spend around 90 percent of our time indoors. Therefore, it is all the more important to ensure a good indoor climate. If you ventilate the room several times a day, you bring fresh air into your home and also reduce the humidity that is generated when showering, cooking, breathing and sweating, for example. For example, a four-person household should release between six and twelve liters of water into the air per day, according to the consumer advice center. However, if the humidity is elevated over a longer period of time, the risk of mould increases – especially if the room temperature is low and the walls are cold. This is another reason why you should make sure to ventilate sufficiently often, but not for too long, when ventilating in winter.
Proper ventilation at sub-zero temperatures: How long should you ventilate?
Continuous ventilation in winter is not a good idea, because it loses a lot of heat energy and cools down the walls. In sub-zero temperatures, however, just a few minutes are enough to direct moist air out of the living rooms. According to the VFF, the following rule of thumb applies:
- If the outside temperature is below 0 degrees Celsius, the windows should only be opened for 5 minutes.
- At 0 to 10 degrees, about 10 minutes of ventilation is sufficient.
- Above 10 degrees, the windows can be opened for about 15 minutes.
In sub-zero temperatures in winter, it is sufficient to ventilate only briefly. © Roman Möbius/Imago
How often does it need to be ventilated?
According to Verbraucherzentrale.de, the air should be completely replaced at least three to four times a day. The more people there are in the household, the more often. You should always keep an eye on the humidity of the rooms. If this regularly rises above 50 percent in winter, the risk of mould increases. From 60 percent at the latest, you should definitely ventilate the room. A hygrometer can help to keep an eye on the humidity.
In the following situations, it is even recommended to ventilate immediately:
- Bedroom: right after getting up.
- Bathroom and kitchen: When showering, bathing or cooking, a lot of water vapor is produced, which should be directed outside immediately.
My news
Which cleaning mistakes you should not make under any circumstances with the glass-ceramic hobread
Three garbage myths that unfortunately still circulateread
Rinse aid is a true all-rounder in the household: Eight surfaces that can be cleaned with itread
New regulation from 2024: Which wood-burning stoves will soon be bannedread more
Hefty penalties for organic waste sinners: New regulation could soon lead to more controlsread
Electricity prices, cable charges and much more: changes for tenants from 2024read more
You can find everything you need to know about household and gardening tips in the regular living newsletter of our partner Merkur.de. Register here!
Open or tilt windows – how do I ventilate properly?
In order to ventilate properly, the windows should be opened wide – preferably also the opposite windows as well as the skylights on higher floors. Because then the warm and stale air rises to the top due to the natural chimney effect.
VFF Managing Director Ulrich Tschorn advises against tilted windows in any case: "Especially in winter, the rooms cool down far too much and moisture can develop in the area of the reveal - i.e. between the window and the masonry. In addition, it is difficult and, above all, expensive to bring the living space back to comfortable temperatures."
In addition to sufficient ventilation, proper heating is just as important
To prevent mould from forming on the walls, you should always keep an eye on the relationship between room temperature and humidity. Warm air absorbs more moisture than cold air and can therefore be better dissipated during ventilation. In addition, moisture likes to settle on cold walls. The Lower Saxony Consumer Advice Centre therefore advises heating all living rooms and bedrooms to at least 16 degrees during the heating season during the heating season. For older buildings, higher temperatures may be necessary to prevent mold. Closed doors also play an important role in heating in winter.