Ventilate basement in summer
Only good ventilation helps against musty smells in the basement. But be careful, in summer this measure can exacerbate the problem. Nevertheless, you do not have to do without fresh air in cool basement rooms during the hot season.
Problems with ventilation in summer
If you let warm outside air into a cold room, there is always the risk that the walls become damp as a result. The problem occurs both during ventilation window as well as ventilation systems.
- Warm air stores more moisture than cold air. One liter of air at 30 ° C can contain more than 30 grams of water vapor. If the air cools down to 10 ° C, it can only store a little more than nine grams of water vapor.
- On a warm, dry summer day, the outside air contains around twelve grams of water vapor per liter. If you let this air into a basement, the walls of which are only 10 ° C, the air in the area of the wall cools down quickly to this temperature.
- At this temperature it can no longer hold the entire original proportion of water, three grams condense into water droplets on the wall. The more air brushes along the cellar walls, the more water falls out. Automatic ventilation systems with a large volume of air also promote moisture in the walls.
Remember that the basement walls are still cold even after the air in the basement has warmed up. The combination of cold, wet walls and warm summer air accelerates the growth of mold significantly.
Be careful if you notice that there is a musty smell in the basement because ...
Fresh air supply in the basement
- The early morning hours are considered the ideal time for ventilation. Because the air has cooled down during the night and lost its moisture. This means that the outside air is coolest and driest in the morning.
- Landlords should install automatic ventilation systems that ensure that the room air is exchanged early in the morning and instruct tenants to keep the basement windows closed during the day.
- If you are not sure whether the outside air is too humid, do a bottle test. Bottles filled with a little liquid that are close to a cellar wall are usually at the same temperature as the wall. Now place one of them outdoors. When the glass steams up, water from the outside air condenses. Under no circumstances should you ventilate. On the bottle you can see impressively what happens mostly in secret on the cellar walls.
You should of course also ventilate the cellar in summer. Without adequate ventilation, radioactive radon collects from the ground in basements and can get into living spaces from there. You should simply never ventilate the basement during the day on warm days. At night and in the early hours of the morning there is little risk of the basement getting damp.