During my first summer in the Netherlands, I constantly left the windows open to let in a breeze — the best I could manage without central air conditioning. But, to my surprise, I also had a natural inclination to open the windows in the winter. Sometimes, the house just seemed stuffy or as though it was lacking oxygen, and I knew I needed fresh air, no matter how cold it was. And when I looked outside, I noticed some of my neighbors, with their windows left ajar, had the same urge. It turns out that this practice is even more common among our neighbors to the southeast.
In Germany, there’s a word — lüften — that succinctly describes the act of airing out or ventilating a space. Sure, we have similar concepts in English, but in Germany, lüften is an everyday activity, similar to bathing or brushing your teeth. There — as well as in other parts of Europe, such as Spain, Croatia, Denmark, and, yes, the Netherlands — some people do lüften every day. And that includes in the winter.
Opening doors and windows for lüften allows fresh air to come in and clears old, recycled air out. When done quickly, with windows opened for just a few minutes, the practice is called “stoßlüften,” or shock ventilation. You’ll often find that European windows are designed to accommodate both types of lüften, with a mechanism to open fully and another to allow the window to remain only slightly tilted. Even if you live in a place where wintertime lüften isn’t the norm, there are several reasons to adopt this German life hack.
Why you should open your windows in the winter
In some countries outside of Europe (and even within Europe), home HVAC systems passively circulate the air so you don’t have to open your windows, which might explain why lüften isn’t as common in places like the U.S. Still, opening the windows in your home, at least for a few minutes each day, can offer a range of benefits, regardless of where you live and the type of ventilation system you have.
One of the biggest reasons Germans swear by lüften is that it can reduce humidity and keep mold at bay. If your house is feeling a little steamy from hot showers, food cooking on the stove, and wet laundry hanging to dry, opening the windows can release some of that extra moisture and prevent mold from growing. Of course, this works best when the humidity outside is drier than the humidity inside — so lüften could backfire if it’s a rainy winter day.
Many Germans also say that fresh air helps them sleep better — and they have the support of those from other countries, such as Norway. Norwegians are known to embrace snoozing in the cold, which is why they sometimes place babies outside in the frigid air to nap (the same is done in other Scandinavian countries, too). Likewise, research shows that one in three Norwegians prefer to keep their bedrooms colder than 12 degrees Celsius1 (about 54 degrees Fahrenheit). While that might seem frigid, there’s scientific evidence that warm temperatures are linked to fatigue and poor sleep,2 while a cool room promotes rest.3
There are also some pretty obvious reasons to try lüften. For one, it reduces stale smells and indoor pollution from things like cooking, fireplaces, and perfumed products. Opening the windows may also eliminate some airborne viruses, cutting your chances of getting that pesky winter flu. Finally, lüften can bring some much-needed oxygen into your space and help clear out carbon dioxide, which is produced every time you exhale. CO2 from breathing might not sound like a big deal, but too much of it in your home can trigger symptoms such as fatigue and headaches.4
How to lüften for better air quality (without freezing)
Lüften can be as easy as opening your windows to air out your space, but there are a few things to keep in mind. First, make sure the outdoor humidity level is on the low side to keep your home from getting too muggy — 60% or lower is ideal. It’s also a good idea to check the air quality in your area before letting in outdoor air. Surprisingly, air quality tends to be best during the day, not at night, though this can vary by region.
Remember that you don’t have to keep your windows cracked all day, every day to reap the benefits. Many Germans prefer stoßlüften, where the windows are left open for five or 10 minutes. This allows new air to cycle in without completely cooling the space (and driving up your energy bill). For the best effect, create a cross breeze by fully opening windows on opposite sides of your home for a few minutes.
If the air outside isn’t too chilly and you want to keep the windows open longer, make sure they’re secure (read: not accessible to strangers) and covered with screens to keep bugs and other debris out.
- https://www.sciencenorway.no/forskningno-norway-sleep/these-are-our-sleep-habits/1447295 ↩︎
- https://www.sciencedirect.com/science/article/abs/pii/S001393511500033X?via%3Dihub ↩︎
- https://news.uthscsa.edu/a-cold-room-not-a-warm-bath-encourages-sleep/ ↩︎
- http://www.peterboroughpublichealth.ca/your-health/home-health-and-safety/carbon-dioxide-co2/ ↩︎