Which wall structure is meaningfully vapor-permeable?

What I see is the gain in comfort. We still have to air out sometimes to get rid of cooking fumes or something similar, the controlled residential ventilation should be able to do that as well.

Correct. I had already written that too. You = uncontrolled / Controlled residential ventilation = controlled (comfortable) What matters is that ventilation happens. And if I can't or don't want to spend money on a controlled residential ventilation, then I'd rather have the drafty window ;-) I'm with you on that.

I have already seen too many filthy controlled residential ventilation systems with central units in my profession,... and I deal with broken tech gadgets every day. The Somfy technician is a speed dial number for me. I am close to converting our own house to door knockers. :D

What is Somfy?

Mainly a manufacturer of motors for roller shutters and the like - including smart home. It is new to me that they also install ventilation systems.

Oh, I don't know that, only newcomers here have [Rollläden]. In summer, when it never gets dark, we simply close curtains in the bedroom. Then it's dark enough to sleep. You do it by hand, and if the sliders don't glide, a bit of Teflon spray helps, presto, it slides again.

No, roller shutters are also seen here more and more often, we got to know them when we lived in Franconia for a few years and definitely wanted to have them on the house. On the other hand, we were strongly advised against [Außenraffstores] because in S-H the wind often causes problems there.

Our general contractor is Specht GmbH, Bisdorf Fehmarn. They only build here. Finesse? I don't know any off the top of my head. It ventilates by itself anyway. In addition, our bedroom window is usually tilted open.

That’s exactly the annoying thing with us in the KFW70 semi-detached house as well: windows constantly tilted open, because it’s just not cool (or is it after all? ;) ) to ventilate every 2-3 hours with a burst of fresh air. I’m just looking forward to a proper controlled residential ventilation system in our new build. But of course, one always defends what one already has ;)