Condensation on windows: what you can do about it

Especially in winter, when it is cold outside and heated inside, condensation tends to form on windows and doors. This condensation is not only visually unsightly, but can also cause long-term mold if it settles in the corners and on the surrounding wall. Find out here what condensation is, what causes it and how you can solve the problem.

Why does condensation form on the inside of windows?

The fact that condensation forms on windows and doors, especially in winter, is a perfectly normal physical process. Warm heated air can absorb more moisture than cold air. This warm air meets the cold window. The moisture it contains condenses when the air cools and condenses in the form of water on the inside of the window. Condensation forms on old, defective windows whose glazing no longer meets current requirements. 
There is also a danger of too much moisture in the air when showering or cooking, or when hanging laundry out to dry in the living room. But even if there is too little ventilation and the damp air cannot get out, the windows will get wet on the inside. This can happen even with new, sealed windows with insulating glass. Much worse, however, is condensation on cold bridges, which are surfaces in the room with cold surfaces such as old uninsulated shutter boxes, inside corners of the room to the outside wall, just to name a few

Where does condensation occur?

Condensation can occur on both windows and doors, for example:

  • The glazing inside
  • On the seals
  • Inside the glass or functional discount
  • On the outside of the glass
  • In the area of the window/wall closure

Condensation can occur regardless of the material of the window, whether it is plastic or wood. Depending on where the condensation forms, it is noticeable in different ways and can be classified by intensity and frequency. Condensation can be point-like, linear, partial or all over the surface, wetting the window and surrounding surfaces only slightly or appearing in the form of barely visible droplets, visible individual drops or even ice.

What to do about condensation on windows and doors?

Perhaps you are still familiar with the so-called condensate pump of your dryer or water heater, which takes care of draining excess condensation. Unfortunately, such a device is not effective at the window. The most effective, cheapest and simplest method against condensation and mold is adequate ventilation. But proper ventilation in the winter is something you have to learn. Brief but effective ventilation is the order of the day in winter to prevent unnecessary cooling of the living space. Tipping windows for long periods of time is counterproductive and expensive. Short-term shock ventilation and preferably cross-ventilation at opposite windows is much more effective. Proper ventilation four to five times a day for five to ten minutes is sufficient in winter. Ventilating once a day is usually not enough to remove all the moisture from the inside to the cold winter air.

If the windows continue to fog up despite proper ventilation, be sure not to ignore it. This can also be caused by leaks, such as damaged or porous seals, which create a so-called cold or heat bridge. In the long run, this can lead to unpleasant side effects, such as a lot of energy loss or mold growth. 

How can you control the humidity in your living spaces?

To prevent condensation as much as possible, a room climate with a humidity of 40 to 60 percent is optimal. You can measure the humidity with a hygrometer and then regulate it as needed by ventilating or heating. If you want to say goodbye to high humidity and condensation, an automatic ventilation system with heat recovery is the right alternative. This ensures a high level of living comfort and energy efficiency, especially in winter. Up to 90 percent of the heat from stale air is recovered. Condensation and mold are then “automatically” no longer a problem.
 

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