zlacker

It’s worse if you live in a well insulated energy-efficient building. In winter it’s cold so nobody wants to open the windows. The lack of ventilation means that the moisture has nowhere to go and just accumulates.

>>zarzav+(OP)
We're in central Europe. A few degrees colder than London in Winter, I doubt it matters. I've done it in houses built a hundred years ago (though they were modernized since, obviously) and ones that were build recently with high degrees of insulation (almost but not quite passive). Not an issue. I usually did open the windows for a couple of minutes.

>>zarzav+(OP)
Shouldn't be if your building was designed properly, with a proper Heat Recovery Ventilator (HRV) e.g. [0]. The long and short of it, fresh air is slightly heated by stale outgoing moist air.

[0] https://www.nrcan.gc.ca/energy-efficiency/products/product-i...