Seemingly many people don't usually, I think it depends on the country/tradition/habits, in the thread I linked to: https://news.ycombinator.com/item?id=253329

Seemingly many people don't usually, I think it depends on the country/tradition/habits, in the thread I linked to: https://news.ycombinator.com/item?id=25332981 https://news.ycombinator.com/item?id=25332981 there are quite a few replies of people that reported how they were not familiar with the concept. And I have to underline how the evolution of building practices (again that depends greatly on different countries/local uses) generally speaking tends to make houses more airtight than before, so that ventilating should be more needed nowadays (with the exception of mechanically ventilated houses).