Home generalAvoid condensation in the window - that helps

Avoid condensation in the window - that helps

general : Avoid condensation in the window - that helps


  • The background of the formation of condensation
  • Relationship between heat and humidity
  • Relationship between insulation and condensation
  • Suitable measures to reduce the risk of condensation
    • airing
    • Even heating
    • Coated insulating glass
    • Insert electrical dehumidifier
    • Non-electric dehumidifier
    • room temperature
  • Immediate action with condensation water

Almost everyone knows the problem: condensation collects on the inside of the window. If the causes are not resolved, the formation of mold threatens. We will show you which measures are effective so that you prevent condensation.

Condensation can form in older as well as in newer buildings. Often it is sufficient to change the heating and ventilation behavior, in other cases it is advisable to replace the windows. One thing is certain, however: if the problem is not resolved, health risks and damage to the house are likely. Seen over medium visibility, the moisture creates mold. After a short time, the water begins to smell unpleasant and it forms mold. It is difficult to remove from window seals and passes to the masonry. The mold spores spread in space and infest other regions. Learn in our guide how to effectively avoid these risks.

The background of the formation of condensation

If it comes to the formation of water on the inside of the windows, some people suspect that the moisture from outside could have gotten inside. In general, however, there is another cause: condensation has formed, which is reflected in the window. Condensation is caused by temperature differences. There is water in the air, which condenses as soon as it encounters colder elements. If it is warmer in the interior than outside, then the moisture is initially in the room air. The cold outside air causes the inside of the window to cool down. The warm air comes into contact with the cooler inside of the window and condenses. Condensation is the transition from the gaseous to the liquid state. The resulting water settles on the glass. Not only the wetness is problematic. There is a risk of mold formation, which is why you must take appropriate measures against the formation of condensation.

Relationship between heat and humidity

The amount of moisture in the air varies. Warm air can bind more water than cold air. Especially in winter the danger of the formation of condensation rises. As soon as you heat indoors, the temperature difference between inside and outside is greater. In the warm air is a high content of moisture, which is now reflected on the cooler window. In cool air less water can be bound. In this context, the dew point is a common term. It describes the temperature at which the relative humidity is 100 percent. In a room, the temperature is not the same everywhere. In some places, the saturation limit is reached earlier, which leads to the precipitation of water. It's always the combination of humidity and temperature that counts. Just a few degrees difference can lead to condensation. Moisture formation can be favored by several factors:

  1. The breathing air and sweating

Humans and animals release moisture into the air. The more people are in a room, the more water collects in the air and can settle on walls and windows. The water is contained in the breathing air, but is also released by sweating.

  1. Daily activities: bathing, cooking, washing

In everyday life we ​​use water in many places, which can get into the air. The shower in the morning, the tumble dryer and the cooking water are just a few examples. They increase the humidity significantly.

Showers generate high humidity
  1. Incorrect ventilation behavior

Ventilation is an effective way to reduce humidity. If the interior of the pool increases in the air, the window must be opened for a sufficiently long but not too long period of time. Ventilation should not lead to a drastic lowering of the temperature in winter, as otherwise the risk of condensation increases again. Experts recommend the airing, so all windows in the apartment for about 10 minutes.

Relationship between insulation and condensation

In the past, houses had various leaks. They inadvertently caused an exchange between inside and outside. The change of air could reduce the risk of condensation. On the other hand, however, could also form bodies that were colder, but allowed no exchange. At these points there was a high risk of mold growth. In modern buildings attention is paid to thermal insulation. The natural air exchange is reduced. For that reason, airing is the only way to regulate.

Which points are special danger spots ">

  • droops
  • outer walls
  • Places with poor air circulation

The positioning of curtains, window sills and radiators contributes to the formation of weak spots in the house. Window sills shield the area under the window and curtains can also prevent the necessary air circulation.

Suitable measures to reduce the risk of condensation


To regulate the humidity, you should ventilate about 3 to 5 times a day. Turn off all radiators and open all windows in the entire apartment or house. Airing a single room is less effective than ventilating the entire building. The air pulls to all places and there is an optimal distribution of the air. Leave the windows open for around 10 minutes and turn up the radiators in the winter immediately after airing.


Even heating

Temperature fluctuations should be avoided if possible. If the temperature drops again and again and then rises again, condensation can settle to a greater extent. Therefore you should ensure the uniform heating of the rooms. If the air has a constant temperature over an extended period of time, it heats the window evenly. The windows fog up to a small extent than at fluctuating temperatures.

Coated insulating glass

The tendency for condensation to form depends on the properties of the windows. The specialist retailers have windows with coated insulating glass, the installation of which reduces condensation. A high thermal insulation value leads to improved retention of the temperature in the interior. The inside of the window is warmer, which means that the humid air only reaches its dew point later. The risk of condensation decreases.

Insert electrical dehumidifier

The reduction of humidity lowers the amount of moisture settling on the disc. Electric dehumidifiers work particularly effectively. You will need to select the devices suitable for the room size for best results. The details in the device description refer to the volume of the room. The value is calculated by the length, width and height of the room. Multiply the three details and you get the volume:

Example: A room is 3 meters long, 4 meters wide and 2.5 meters high. In this case, the volume of the room is:

3 mx 4 mx 2.5 m = 30 m³

Cost of electric dehumidifier

The prices for the dehumidifiers vary greatly. Powerful models for a single room are already available for about 70 euros. Other devices cost 100 or 200 euros. Particularly advantageous are mobile devices, since they can use these as needed for different spaces. When choosing dehumidifiers, you must pay attention to various technical data:

  • power consumption
  • Air flow per hour
  • maximum amount of water per day
  • Dimensions
  • portable or not portable

Example calculation for energy consumption

A realistic power consumption value for a dehumidifier is 200 watts. Let's say you run the device for 5 hours a day. Then you consume 1, 000 watts within 24 hours, ie 1 kW. The kWh costs depending on the provider about 28 cents. The operation generates operating costs of 28 cents. This value may seem low at first glance, but keep in mind that this is the cost per day and per room. If the dehumidifier is used every day of the month, then in our example you will have to spend with

28 cents x 30 = 8.40 euros per month.

Since in an apartment usually not only one room is affected by the problem, it is worthwhile to pay attention to the information on the power consumption when selecting the electrical appliances.

Non-electric dehumidifier

Non-electrical dehumidifiers work by means of a granulate that absorbs the moisture. The water is absorbed and stored. If the granules swell and can not absorb any more moisture, then replace it and the dehumidifier is ready for use again. The amount of water that can be absorbed depends on the particular granulate and the moisture contained in the device. For small moisture problems, this variant is a good solution, since it does not lead to any power consumption. The costs for the dehumidifiers are around 15 to 20 euros . Refill packs are offered, through which the dehumidifier can be used for a long time.

room temperature

If rooms are not sufficiently heated, then there is an increase in humidity and increased mold growth. You should therefore pay attention to a room temperature of at least 20 degrees Celsius. Room temperature fluctuations should be avoided to avoid condensation.

Immediate action with condensation water

Once you notice the accumulation of moisture, you should wipe and dry the window dry. It is important to avoid water getting into cracks and mold. In winter, long airing is problematic, which means you have to wipe dry manually. Turning on the heater after airing eliminates any residual moisture. Wiping the water has the advantage of removing all traces of moisture and leaving no unsightly stains behind.

Remove condensation

The tilt function is not sufficient

Many people do without opening the entire window and instead use the tilt function. However, the relatively small opening does not serve its purpose, which is why the formation of condensation is not reduced to a sufficient extent. Only by opening the complete window you fight the causes. Butt ventilation is also beneficial in terms of heating costs. Would you put the window on tilt, then there would be a permanent escape of heat. On the other hand, if you ventilate for a short time and then close the window again, you save energy costs.

Avoid chemical agents

Specialist dealers offer special products which are to be applied to the window pane. They serve to prevent the adhesion of moisture. However, chemical agents should be avoided, as they are harmful to health and, secondly, do not fight the causes. Even if the moisture on the window can not be reflected it is still present. The water will collect on the windowsill or deposit on walls. There is only a shift of the problem. The high humidity is still present and must be eliminated. Chemicals should be avoided as much as possible, as they cause long-term and spontaneous damage to health.

Tips for quick readers

  • 3 to 5 times every day
  • open all windows for about 10 minutes
  • Remove condensation from the window
  • Condensation leads to mold growth
  • Install coated and insulated windows
  • Reduce humidity
  • Insert dehumidifier
  • electric dehumidifier / dehumidifier with granules
  • avoid chemical agents
  • Tilting the window is not enough
  • constant room temperature
  • at least 20 degrees Celsius room temperature
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