– Here you can find out how condensation forms in the first place, how to prevent it indoors and when condensation is actually a good sign.
When it is cold outside, small droplets often form on the window panes and run down. Condensation is familiar to everyone – and to many it is terrifying because: where too much moisture accumulates, mold is not far away.
How does condensation form?
Especially in winter, when it is cold outside and you are heating inside, condensation or dew water forms on the window panes. Small globules of water form when moist warm air meets a cooler surface. But the liquid doesn’t come out of nowhere. Moisture in warm air only changes its physical state from gaseous to liquid. It is when moist air is cooled to a certain temperature, the so-called dew point temperature, as wetter.de explained.
Warmer air can hold more moisture than cold air. So if warm, moist air hits the cold glass, it gets cold. As a result, it can no longer absorb as much moisture. Excess moisture settles on the glass – condensation forms. The same principle occurs in nature when fog is formed, dew drops on a blade of grass or in a spider’s web.
How to counter this?
Windows are usually the coldest surfaces in the house in the winter, so condensation accumulates there. To counteract this effect, German Weather Service (DWD) Ventilate, preferably several times a day. This means that cooler air enters the room, but it immediately mixes with indoor air and very humid air immediately outside the window. As a result, the relative humidity of the air near the window decreases – and with it, the risk of mold growth.
The same principle works for the formation of droplets on the outside of the window. However, unlike inside the window, condensation is not a problem here, on the contrary, it is even a sign of quality: it is a sign of good insulation. When water condenses on the outside, it means that almost no heat escapes from the inside. Only then can the glass cool down and moisture can condense on it.