Me: Let’s open the windows and get some fresh air in.
American partner: But it’s cold outside!
We love to air out our homes – and remember, a lot of Germans do not have air-conditioning, or air filters, or 500 varieties of air fresheners. If you get too cold, just leave the room, close the door, and wait till the “lueften” (airing out) is over. Also, many German homes are smaller than their American counterparts, thus the air does get stuffier more easily.
And don’t forget: fresh air is medicinal, or so we believe in Germany (and probably other parts of Europe, too). Why else would there be the term “Luftkurort“, whose English equivalent “climate spa” or “climate health resort” is not really a familiar concept? Ideally, you go to the mountains or the seaside, and breathe, breathe deeply. If you can’t afford this, just open your windows once a day, that’s better than nothing. Should the season happen to be winter, remember Friedrich Nietzsche : “Was uns nicht umbringt, macht uns staerker.”
Funnily, one typical situation of windows NOT being opened is during car rides. You might be stuck, with Germans, on a very hot day, in a car, and they will not let you roll down the windows. If you did, you and everybody inside would be exposed to the much-feared DRAFT. But that’s another story.