20% humidity in KFW 40+ new construction

I had hoped for a more technically global measure to address the problem.

Just open the window a little at night?

Simply open the window a little at night?

That would be exactly the wrong way! Wastes heating energy endlessly. And with 60% relative humidity outside currently at 0 degrees, that corresponds to 2.91g/m³. Heating this air to, say, 18 degrees then results in 19% relative humidity. Very uncomfortable and unhealthy!

This air then heated to, say, 18 degrees has then 19% relative humidity.
Very unpleasant and unhealthy!

Then we will die soon :eek:,
we also sleep with the window open and fresh air and the noise of the birds first.
We live in the house like generations before us (I know, they are already dead) and not in a bunker
PS: Heating costs 2500kwh per year, so infinitely much

That would be exactly the wrong way! Wastes heating energy endlessly.

And what if you turn off the underfloor heating in the bedroom? We are window-open sleepers and need the "cold" from outside. We will also build with controlled residential ventilation KfW55 but that would really bother me. Otherwise maybe close the air ducts?!

And what if you turn off the underfloor heating in the bedroom?

Our heating in the bedroom and storage room is constantly off

Sorry for the interjection about heating energy waste. I still believe, of course, that leaving the window open in modern houses nowadays is a no-go, but it simply has nothing to do with this topic. Let's just stick to the moisture issue here. It’s best to refer to my calculation if you think leaving the window open would do something good for the humidity!