BERLIN — After moving to Berlin from Honolulu, Wyatt Gordon was surprised when his new German roommate marched into his bedroom at 8 a.m. and threw open the windows.
It turned out that his cohabitant, Laura, maintained a strict ventilation regime. Three times a day, at precise times, all the windows in the apartment needed to be opened. It didn’t matter whether it was the dead of winter or a weekend morning, or if Gordon had company — rules were rules.
“I had men and women in my bed that I’d brought home from the club or wherever,” said Gordon, now 35, a city planner originally from Richmond. As is common on Berlin weekends, they would crawl into bed around dawn — “only to be woken up an hour later by a blast of ice-cold air,” he recalled. “How do you explain to the person laying in bed next to you that this is what the German culture demands of us?”
How, in other words, to explain lüften?
Lüften, meaning “airing out” or “ventilation,” is dogma in German households. Rain or shine, hot or cold (which, in Berlin winters, can be bone-numbing), windows must be opened several times a day to exchange stale indoor air for the fresh outdoor stuff.
Ventilation, of course, is part of life in much of the world. Germans, however, have codified it in an especially German way. Many apartment leases here contain a “lüften” clause, requiring tenants to open their windows multiple times a day, even — or especially — in winter. German courts have ruled that, absent specific landlord guidance, a tenant is required to open windows twice a day, morning and evening, for 10 minutes each.
German parents don’t have to teach lüften to their children, said Lukas Gesche, 34, a Berlin native and dedicated lüften practitioner. “When we’re kids, we see how our parents constantly open the windows,” he said. “It’s like learning the language — it happens automatically.”
But it’s a concept that leaves many visitors cold. And it can be a particular source of culture shock for Americans accustomed to a climate-controlled environment who previously regarded windows as mostly decorative.
Now, however, Germans are getting their own lüften shock. The trend has suddenly gone viral on U.S. social media — and, to Germans’ horror, some Americans are claiming it as their own, with a new name.
In recent months, wellness influencers on TikTok have taken to promoting the trend of “house burping,” or periodic window-opening. That’s prompted a flood of mocking response videos from Germans astounded that Americans claim to have just “discovered” lüften — and that they’re calling it house burping.
Here’s why “burping” your house each day matters: 1. Fresh air reduces indoor pollutants. Indoor air can actually be 2–5 times more polluted than outdoor air because of things like cooking fumes, cleaning products, and off-gassing from furniture. Cracking windows for even 10–15 minutes a day helps clear that out. 2. It lowers germ buildup. During colder months especially, homes are usually sealed tight, and viruses (like cold and flu) spread more easily in stagnant indoor air. Letting in fresh air helps disperse airborne germs and reduces how long they linger. 3. It balances humidity. Heated indoor air gets dry, which can irritate nasal passages and make people more vulnerable to infections. A quick air exchange can help regulate humidity levels (which lowers the possibility of mold-build up). Tips for Burping Your House: • Open windows briefly (10–20 minutes) once a day, ideally when the outdoor air quality is good. • Choose midday when it’s warmest to minimize heat loss if that’s a concern. • Open windows on opposite sides of the house for cross ventilation. #healthyliving #cleaningtips #momhacks #freshair #fluseason
Culture shock ventilation
Sarah Armstrong, 36, moved to Berlin from California in 2022 to be with her half-German, half-Dutch boyfriend. Lüften is largely responsible for the fact that they’re no longer together.
Early in their relationship, she came home to find every window in their apartment open. “I was just confused,” she said. “Had something caught fire in the kitchen? And then he explained lüften to me.”
Their rental contract, he told her, mandated daily lüften. But he didn’t stick to the minimum requirements; he insisted that every window and door be open all night, even in the winter. It was an extreme version of the widely practiced stosslüften, or shock ventilation, in which all windows are opened for a short period. (A close relative, querlüften, or cross-ventilation, emphasizes opening windows on opposite ends of a home.)
Armstrong’s Boston terrier would dive under the covers as soon as the windows were thrown open. Armstrong and her boyfriend lived in the Kreuzberg neighborhood, known for its nightlife, and the noise often kept her up. One night, three bats flew into the apartment.
“Lüften actually became one of the bigger friction points in our relationship,” Armstrong said. “One night, we were arguing in bed, and we were like, we can’t do this every night.”
She eventually moved out — into a building with no lüften requirement.
#Duett mit @Aimee Goeman #Winter #stoßlüften #germans
The science behind lüften
The need for ventilation has grown as homes have been modernized and old windows replaced with new ones that are more or less airtight, said Lars Gunnarsen, an internationally recognized ventilation expert at Aalborg University in Denmark.
“The old leaky houses are not so leaky anymore,” Gunnarsen said. “And the message in relation to that is that you need to take control and do some ventilation yourself.”
Absent ventilation, Gunnarsen said, moisture buildup can lead to mold, and carbon dioxide accumulation can make you feel sluggish and less productive and cause headaches. (Unlike carbon monoxide, it won’t kill you except at unrealistically high concentrations.)
Gunnarsen’s recommendation is a form of querlüften: Open windows at opposite ends of the home to allow a strong cross-breeze, for as little as five minutes in the winter, so little energy is wasted but air is exchanged and moisture released.
But this applies only if a home doesn’t have a built-in ventilation mechanism. New multiunit buildings in Denmark are required to have ventilation systems that use fans to exchange air, Gunnarsen said. In the United States, many homes with forced-air heat and central air conditioning have built-in ventilation systems.
A typical German apartment, though, is heated through radiators. There’s no air conditioning or ductwork, and the windows are tightly insulated.
German parents harangue their children and teenagers to air out their rooms, Gesche said. “They always say, ‘Oh, the air is so stale,’ ” he said. “And that means there’s simply no oxygen left in the room. You’ve breathed it all in. You always have to open the window to get some oxygen.”
Gesche aims to open his windows three times daily, though he sometimes has to miss his midday lüften session when he’s out of the house. In the winter, each round of lüften lasts only five minutes, but the windows must be opened fully; in the summer, when air exchange takes longer, he ventilates for half an hour at a time.
It’s not just a matter of personal habit; Gesche’s apartment lease requires him to practice lüften.
“Adequate lüften and proper heating,” he read aloud from his lease contract. “In winter, both are particularly important and are prerequisites for a comfortable indoor climate. Proper ventilation means opening the window wide for 10 to 15 minutes several times a day.”
For more information, the lease refers him to a brochure titled “Proper Heating and Lüften.” It’s quite specific in its guidance: Lüften should be practiced to achieve a relative humidity of 30 to 40 percent when it’s under 5 degrees Celsius (41 degrees Fahrenheit) outside but between 22 and 24 degrees (71.6 to 75.2 Fahrenheit) inside, for example, while 50 to 60 percent humidity is acceptable when it’s up to 15 degrees (59 Fahrenheit) outside but between 19 and 21 degrees (66.2 to 69.8 Fahrenheit) inside.
Also, to avoid inhibiting airflow, the brochure says, furniture in buildings constructed before 1995 must be placed at least 10 centimeters (about four inches) from any exterior walls. In newer buildings, a five-centimeter gap is allowed.
‘The air gets disgusting somehow’
Europeans are known to have a predilection for fresh air, but the German obsession with lüften still baffles many. Mikael Wessen, 36, rents out the small guesthouse next to his home on the Swedish island of Sturko, and he picked up on a strange habit among his German guests.
“Every time we had Germans over, we noticed that they opened their windows a few times a day,” he said. “We couldn’t figure out, why do they all do it?”
His guests explained their concerns about mold and carbon dioxide in tightly insulated homes. But Wessen’s guesthouse is an “old, rustic, simple structure,” he said — “if it’s windy outside, it’s almost windy on the inside.” Still, his German visitors insisted on opening up the windows daily, even when it was subfreezing outside, not an uncommon occurrence in Sweden.
Befuddled, Wessen took to Reddit to ask why Germans are so fixated on lüften. He was barraged with indignant responses from Germans: “Like, ‘You have to lüften.’ There’s an idea that if you don’t do it, the air gets disgusting somehow.”
During the covid pandemic, lüften took on an outsize importance in Germany.
Then-Chancellor Angela Merkel promoted lüften as the “cheapest and most effective measure” to combat the virus. The federal Environment Ministry issued lüften guidance, recommending, among other things, opening the windows five times per hour in a room where people were exercising. Somewhat unhelpfully, the guidance added: “However, drafts should not occur in the room.”
Which raises a curious point: For all their fear of stale air, Germans are nearly as afraid of drafts. It’s not uncommon for someone to enter an apartment (or classroom or train or bus), remark on the stagnant air and theatrically open a window, only for someone else to complain a minute later about the draft and just as theatrically close it. After all, there is a German saying: “Many people have frozen to death, but no one has died from a bad smell.”
Then again, sometimes a house just needs to burp.
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