Which central ventilation system?

Thank you! Then I should keep an eye on the humidity to see if it also rises with increasing temperatures. Currently, it hovers around just under 30%, which I personally do not find uncomfortable.

I suspect that this will lead to long-term problems - if it's only a few days/weeks per year, it will hardly cause real problems in the [Massivhaus].

It's different with, for example, the rare but occurring [Massivholzhaus] - according to my uncle (carpenter), one should avoid that.

For a piano or grand piano, 30% RH over a long period is deadly... Other wooden instruments the same. Also for antique furniture, etc.. not ideal.

<= Helios with enthalpy exchanger - but not yet in operation. All rooms with KNX humidity sensors; if the humidity is too high, the bypass is simply activated.

With the ventilation system, you should make sure that the filters can be procured cheaply and replaced easily. With us, there was no choice; we now have to use such cassettes. The advantage is that you can't do it wrong. The disadvantage is that they cost significantly more than a meter of this filter fleece.

We once lived for a day without the ventilation system because I forgot to plug it back in after cleaning. You immediately noticed how everything became damp; water collected on the inside of the windowpane and the climate wasn't very good either. It seemed strange to me, so I checked what was going on. Plugged it in, ran it full blast for a few hours, and everything was great again.
We dry our soaking wet laundry completely in the upstairs bathroom without ventilation. The room is always dry except for the freshly hung laundry. After a few hours of hanging fresh laundry, I open the window for 1-2 minutes; the moist warm air disappears in a rush, and then it doesn't get damp again.

I wouldn't build without such a system anymore!

So I have already read and heard quite a bit about Hoval. Two friends have installed one or will install one. In my case, it will also come down to a Hoval, even if it will probably be more expensive.

What is the amount of your offer for how many square meters?

What about the parquet and the ventilation system? It's probably not that great either..