Controlled residential ventilation and still open windows at night

@Alex Helios. But there are also other comparable companies.

on the go

A ventilation system is designed to bring fresh, unused, oxygen-rich air into the house.

... with heat recovery and preferably also with moisture recovery. The rest of your post, in my opinion, compares apples and oranges (ventilating via controlled residential ventilation vs. not ventilating at all?) using a very unusual example (-20 °C); in my opinion not very sensible, although I appreciate many of your other posts.

Yes, air is a poor conductor of heat.

Nitpicking mode: Here it sensibly referred to heat capacity, not heat conduction. I don't want to comment on the rest of his calculation, I have not understood it (it could be correct, but does not have to be; was moisture taken into account?).

My thoughts are thus:
- From the perspective of dryness, controlled residential ventilation seems mercilessly oversized to me.
- Shouldn't turning it down then bring improvement?
- But 2x air exchange per day is not that much now. 2x window ventilation is also 2x air exchange but retains more moisture?!
- I am afraid that manual ventilation might become too little and is sometimes skipped due to time constraints, but controlled residential ventilation seems to go too far in the opposite direction, there should be something reasonable in between (for KfW5)

1. Moisture recovery or humidifier or not ventilating (dry air during the heating period has nothing to do with whether a controlled residential ventilation system is installed, but only with whether ventilation occurs at all). Possibly, however, run the controlled residential ventilation at a lower setting (higher humidity, higher CO2 content).
2. Yes, regarding moisture, not regarding "good" air.
3. It depends.
4. You can run the controlled residential ventilation at any level you choose. Generally, the rated capacity fits, the standards are not that unreasonable.

So the installer told us that after a hot steamy shower one should even open the window...

We refrain from doing so (opening the window, not showering), it is apparently not necessary with our controlled residential ventilation. Disclaimer: Anyone who wants to can and may of course open the window!

When I shower in the basement bathroom without a window, it gets "normal" again relatively quickly.

If necessary, use the [Kacketaster]

We have exhaust air in the bathrooms and kitchen, and supply air in the other rooms, i.e. in these exhaust rooms the throughput (because of less area compared to the other rooms) is significantly higher in relation and therefore there are few problems with moisture/odor.

von unterwegs

So when Madame has blasted about 150 liters of water that feels scalding hot to me through the showerhead in winter, you can't see anything in the bathroom anymore at first. Surely the ventilation would eventually manage it too, but I prefer to open the window...

Dimension ventilation correctly and/or adjust