Online communities are discovering a simple German trick that’s taking the hassle out of tackling damp and mould.
The UK’s consumer rights authority, Which?, known for assessing products and services, has shared the hack through their social media channels. Demonstrating the Stoßlüften technique in an Instagram reel, Which? showed how opening all windows in the home for five minutes twice daily can effectively combat mould. ‘
Stoßlüften combines the words ‘shock’ and ‘ventilation’, reflecting the technique’s abrupt approach to airing out spaces. This method provides a swift, straightforward, and economical solution to household mould issues.
In their Instagram video, the spokesperson from Which? explained: “Have you got a damp house? Well this is what the Germans would do about it and it’s basically free.”
They continued to underline alternative approaches, saying: “Some ways of conquering damp can be expensive or require a fair bit of DIY. Germans have a great habit that anyone can get into: Stoßlüften, literally shock ventilation.”
To further advise on the process, they suggested: “Wrap up warm, run around the house and open all your windows wide for five minutes twice a day. Yes, even in the freezing cold!”
Adding detail, he noted: “The warm, damp air in your home will quickly get replaced with cold, dry air. When you’re sealed back up again the temperature should quickly get back to comfortable but now the moisture in the air is banished and won’t be condensing in damp patches on your walls and windows.”
The tip, shared on Instagram, has received significant attention with 3.5 million views, 37,000 likes, and nearly 1,000 comments. One user commented: “What great advice. I have a German/Dutch brother in law and a very good German friend and they always sleep with the bedroom window open.”
Another added: “The lung clinic at my chronic asthma hospital team also recommend this – get them windows open!” A third individual, who has successfully used this method, stated: “Done this for years, in a council block, that has huge issues with damp and mould. Works perfectly and really is a life saver.”
Multiple users in the comments section shared similar success stories after trying Stoßlüften. A woman residing in a cottage mentioned: “I open my windows every day all year. I live in a very old cottage with no damp proof course. And no damp at all inside. So it works. I’ve always needed fresh air. Glad I’m doing something right.”
Nevertheless, some UK-based users expressed skepticism, citing that the “air in England isn’t dry, it’s damp, especially at the minute” with many others agreeing with this sentiment. One individual has debunked this common misconception, stating: “A lot of people in the comments seem to mistakenly believe that the cold air outside their house is as humid (or even more humid) than the warm air inside their house. This isn’t true: cold air has a much lower carrying capacity: it can’t hold as much water vapour as warm air.”
They further explained: “When you open your windows, the dense cold air flows into the house replacing the less dense warm air (which is driven outside). This means that you have replaced warm air with a high moisture content with cold air with a lower moisture content.”
The person added: “As that cold air warms up inside your house it absorbs moisture from surfaces and materials. Doing this multiple times a day will therefore move moisture from inside your house to outside your house.”
Consumer watchdog Which? also responded to those who argued that the UK’s damp air would render window-opening ineffective against mould. In a follow-up video, a spokesperson clarified the “confusion between relative humidity and absolute humidity.”
Using two glasses of water for illustration, one small and full, the other larger but less filled, he said: “This very full glass is like the air outside on a cold day. It’s at 95% capacity. It is holding as much water as it’s capable of holding but warm air can actually hold almost twice as much in a house compared to the cold air outside.”