Be careful when saving heating costs – beware of the risk of mold

Not only because of the sharp rise in energy prices, but also because of climate protection, saving energy and heating costs is becoming increasingly important. Checking your own heating behavior is a good start. Tips for saving energy are now being given everywhere, cool rooms are almost de rigueur. However, you should be careful not to overdo it with the savings. Rooms that are too cold carry the risk of mold growth. But if you take a few things to heart when heating and ventilating, you can prevent this and still save.

How does mold develop?

Mold needs moisture and nutrients to grow and thrive. Mold finds the nutrients in houses and apartments in the form of wallpaper, plaster, fabrics or wood. Mold needs a humidity of over 60 percent, below which it does not feel comfortable. Moisture in apartments and houses can develop quickly, especially in bathrooms and kitchens, but also in bedrooms (people exhale around 1 liter of liquid per night).

Proper ventilation

Around twelve liters of water evaporate every day in a four-person household. Especially with very tight windows and doors, it is therefore necessary to air them regularly so that the humidity is always between the lower and upper limit of 30 percent and 60 percent. For this reason, the room should be aired with the windows wide open for around ten minutes at least twice a day, better three times a day.

Ideally, you should also open a window on the opposite side of the house to ensure a short-term draft. A high air exchange rate can only be achieved through this so-called cross ventilation. This is the best way to exchange the used air for fresh air. Incidentally, the air exchange rate indicates how much air of the volume is exchanged in a room within one hour. With an air exchange rate of 2/h, the entire air volume of the room would be replaced twice with fresh air.

The heating should be turned off via the thermostats while the room is being aired, since the inflow of cold air would otherwise cause the radiators to be heated up extra. Incidentally, the energy loss during ventilation is not as high as some fear. Masonry and furniture have a significantly higher heat capacity than air, so they retain heat.

Having the window permanently tilted is by no means an alternative to forced ventilation. The exchange of air then takes much longer – up to 75 minutes. Since the walls also cool down a lot during "continuous ventilation", the risk of moisture infestation increases. Last but not least, constant ventilation is counterproductive if you want to save on heating costs. It takes a lot of energy to reheat a room that has cooled down too much.

Having the window permanently tilted is by no means an alternative to forced ventilation. The exchange of air then takes much longer – up to 75 minutes. Since the walls also cool down a lot during "continuous ventilation", the risk of moisture infestation increases. Last but not least, constant ventilation is counterproductive if you want to save on heating costs. It takes a lot of energy to reheat a room that has cooled down too much.

In bedrooms, on the other hand, around 16 degrees is sufficient. The same applies to the kitchen. The thermostat is set to level 2 (usually). In little-used rooms, such as hallways, corridors or unused guest rooms, the thermostat setting can even be set to 1. However, it is important that the temperature does not drop below 14 degrees.

By the way: In addition, around a quarter of the energy that is consumed each year is used for heating. If you lower the temperature by just one degree, you can save around six percent on heating costs. So if you manage with 20 degrees instead of 24 degrees, that means a saving of 24 percent.

Too cool rooms

The temperature in rooms should not fall below 14 degrees. On the one hand, it takes too long to bring these rooms up to a higher temperature again. In rooms that are permanently too cold or that are never properly heated, there is also a risk of mold as the moisture condenses on the cold walls. Depending on the type of mold, the infestation can become visible after just four days. In addition, in less heated rooms, such as bedrooms, the doors should remain closed.

Because with the heat, moisture also penetrates into the cool room. The latter can condense on the cooled walls, which in turn promotes mold growth.