Causes of high humidity

Proper ventilation and causes of excessive humidity

How does excessive humidity occur and what can be done about it?

High humidity can manifest itself through fogged windows, dripping pipes, or even mold growth on the walls. All of these are warning signs that you should take action. With little effort, you can monitor the condition of the rooms, where in winter, bedrooms and living areas tend to be too humid (homemade moisture from cooking, washing, showering while simultaneously reducing ventilation), and in summer, basements and archive rooms (due to the influx of warm air from outside into cooler areas). To measure the humidity in your rooms, you can use a so-called hygrometer. But what if it actually shows a too high value?

If your rooms are affected by excessive humidity and are therefore at high risk of mold, this can be dangerous for the building structure as well as for the health of your family. In this case, you should first look for the causes of the poor indoor climate. Only then can you take the optimal countermeasure.

The three most common causes of high humidity in living spaces are:

1. Lack of natural air exchange

Modern houses and apartments are increasingly better insulated. They are energy-efficient and perfectly "tight" down to the last seal on the window. This saves electricity, heating energy, and a lot of costs in this regard. However, unfortunately, this also means that the natural air exchange between indoor spaces and the outside air is lacking. As many advantages as modernizing your living spaces or moving into a new building can have, it often also brings a significant disadvantage: a poor indoor climate.

2. Incorrect or too infrequent ventilation

Excessive indoor humidity can also occur if you do not ventilate, ventilate incorrectly, or ventilate too infrequently. Especially when natural air exchange is lacking, "artificial" air exchange is particularly essential for a good and healthy indoor climate. This is especially a common cause of mold or unpleasant odors in winter or in properties that are only used occasionally.

3. Thermal bridges or inadequate insulation

And finally, construction defects, outdated, porous, or defective insulation can also be responsible for poor indoor climate. Especially in winter, the cold outside air can cool the walls to such an extent that the indoor air cools and condenses on the cold walls. This can lead to mold formation sooner or later, which usually first becomes visible on north-facing walls or behind cabinets (which are placed directly against the wall).

Countermeasures for a damp living space

Regular ventilation is an important measure against excessive moisture in the apartment, especially – but not only – in modern buildings without natural air exchange. Ventilate several times a day, especially in winter. The so-called "draft ventilation" is recommended, where you fully open opposite windows and doors. If that is not sufficient, the use of a dehumidifier can be considered as a relatively inexpensive solution to alleviate the problem. It filters the excess moisture from the indoor air and thus prevents mold formation and potential health risks. A dehumidifier also has a cleansing effect on the indoor air, as the extracted condensate simultaneously binds fine dust and washes it into the bucket.

Ventilation in a damp cellar

Especially during the warm summer months, high humidity often builds up in basements due to weather conditions, which can lead to unpleasant odors and mold. It is important to understand why this happens: warm air can hold more moisture than cold air. When warm air from outside enters a cold basement in summer, the air cannot carry as much water due to cooling as it can in the warm outdoors. The relative humidity (which is the moisture visible on the hygrometer) increases. Relative humidity indicates how much % the air is saturated with water in relation to what it can hold at the current room temperature. The same amount of water per cubic meter means a lower humidity in a warm environment than at cold temperatures. If the humidity in the basement rises too much, condensation begins to form in cooler areas. The result is damp walls and even dripping cold water pipes. Regarding ventilation, this means that a damp basement can occasionally be ventilated by cross-ventilation in summer to bring fresh air into the room. Ideally, this should be done in the evening when the outside temperature is as cool as possible. Keeping tilt windows open all day is deadly for the humidity balance in the basement, as it continuously allows moisture to be drawn into the basement. If the basement climate cannot be satisfactorily resolved with occasional cross-ventilation, a dehumidifier helps quickly, reliably, and comparatively cheaply. It protects the rooms from mold in summer and can also be used effectively in winter for faster drying of laundry.