A few years ago, a building contractor told me a story that scared me enough to change my habits:
“I worked with a young couple recently who fully remodeled an old house. They both worked full-time. Every morning, they both got up, took showers, got dressed and left for work, to return again late in the evening. Within three months, mold had taken over in multiple rooms of their house and they spent a fortune to have the problem fixed. Not once in those three months did they air out after taking a shower, and all the moisture just built up in there.”
After hearing this story, you can bet I open the windows and air out the bathroom after a shower! And for good air quality in your house, to prevent mold, and to increase heating efficiency in the winter, you should also air out (lüften) your home regularly.
German buildings are not typically built with extensive ventilation systems and don’t use forced-air heat the way many homes in the US do. Most buildings here are fairly air-tight and have no ventilation except the windows and doors, and heat is radiant, whether from radiators or in-floor heating.
According to the brochure available online from the Verbraucherzentrale Energieberatung, a four person household will create about twelve liters of moisture per day. Regularly opening your windows and airing out your apartment will regulate the humidity inside – and should be done two to four times daily, plus after showering, cooking, or mopping the floors.
German windows are fantastic: they open fully for easy cleaning, and they have the “kipp” (tilt) mechanism which allows you to let just a little air in. However, when you are doing your big lueften, you should open the windows all the way – opening them just a crack will actually cause condensation around the window and could cause mold. Plus, getting a full exchange of air in a few minutes’ time by opening all the windows is a more efficient energy use than leaving a window cracked and letting the heat escape over a longer period of time.
So as you head into this winter, keep in mind that a healthy house is an aired-out house, and keep things fresh instead of stuffy!
I can vouch that the homes in Germany can be air tight! When my girlfriend and I lived in an apartment near Munich, our bathroom had no windows…only a fan. Luckily, we never had a mold problem in the bathroom. Of course, the steam evaporated and went to the main windows in the livingroom, and that’s when I then found mold around the window panes. A little bleach with water took care of the problem. As Ruth pointed out, opening the window wide open is recommended to let out the moisture and stuffy air. Just remember to close the window after a certain period of time to make sure your heat is not going out the window during this winter time.
This is one advantage of forced-air heating, common in the USA: It reduces indoor moisture (which can also be a disadvantage!). Since most homes and apartments in Europe have hot-water/steam radiation heating, moisture can build up inside. I experienced this problem when I was living in Berlin: mold behind bookshelves. As Ruth says, regular airing (with wide-open windows) is important.
It’s really depressing to, after feeling not quite warm enough all day (because hey, it’s winter), to FINALLY warm up to heavenly levels in the shower, only to have to get out and immediately let the freezing cold air into your apartment through all windows for a minimum of five minutes.
But, it’s the price you have to pay to live in a country with enough vacation time and reasonable health care coverage, I guess…..