Controlled residential ventilation yes - heat recovery no - justification in the text!

So the air conditioning doesn't have to fight against the controlled residential ventilation?

On the contrary, the controlled residential ventilation cools the incoming air with the heat exchanger (if it is cooler inside than outside), so you are not ventilating warm outside air into the house. Therefore, the condensate drain of the controlled residential ventilation should definitely be connected; it is also important that the bypass that some controlled residential ventilations have is then deactivated (bypass = air flows past the heat exchanger).

We will probably install the controlled residential ventilation.

Retrofitting is not possible and controlled ventilation should definitely be included. In the worst case, the controlled residential ventilation can be converted into an exhaust system, but I just hope that everything works as promised. I would never opt for purely manual ventilation in a new house. For me, it was more a question of a central exhaust system with decentralized supply air or a central supply and exhaust system with heat recovery.

Thank you for your answer. However, I will probably decide against it. Not because of one central point, but because of several things. Since I want to build with bricks and mineral plaster inside and outside, there should be no problems without a ventilation system just because of the humidity. It is, of course, different with diffusion-tight systems like aerated concrete + Styrofoam or airtight prefabricated houses.

Your bricks and plaster are basically just as much a barrier to moisture as other building materials. Try blowing through bricks. It doesn’t work even if you put your mouth right up to them. They are just as airtight as other building materials (fortunately, because that is mandatory). The diffusion resistance is orders of magnitude too high to transport moisture out of the house. Otherwise, it would get quite damp when it rains (because it works both ways!). The idea that walls breathe is more of a myth. If anything, it happens through gaps or holes. The truth lies somewhere in between, but not where you suggested.

Bricks and lime plaster do not help you at all with today's new buildings. And they also do not bring 30-40 m3 of fresh air per person per hour inside, which every person needs. A brick house is just as airtight as a prefabricated wooden house.

An old building has a natural air exchange rate of over 1, there are no problems (joints, windows, etc.). Such old buildings come to values of over 10 in blower door tests, as I have read somewhere. Today's new buildings have a natural air exchange rate of partly under 0.1 depending on the wind (blower door test mostly under 1.0).

If you build without any kind of ventilation, then prepare yourself to ventilate by shock/through ventilation at least 5 times a day and that this is just enough to avoid mold, but good air is gone even an hour after the last ventilation.

At least take a central exhaust system with outside air inlets. But from there it is not far to controlled residential ventilation.

Your bricks and plaster are basically just as much a barrier to moisture as other building materials. Try blowing through bricks. It doesn’t work even if you put your mouth very close to them. They are just as airtight as other building materials (fortunately, because that is required). The diffusion resistance is orders of magnitude too high to transport moisture out of the house. Otherwise, it would also get pretty wet when it rains (it works both ways!) The idea that walls breathe is more of a myth. If anything, it happens through gaps or holes. The truth lies somewhere in between, but not at the point you suggested.

Of course, that alone is not enough, but together with proper cross-ventilation, there should be no moisture problems at all. Moreover, an estimated 80% of people here build like that (yes, I know that doesn’t mean much )

I might also add a decentralized system like BluMartin.

Bricks and lime plaster won’t help you at all with today's new buildings. And they also don’t bring anywhere near 30-40 m³ per person per hour of fresh air indoors, which every person needs. A brick house is just as airtight as a prefabricated wooden house.

An old building has a natural air exchange rate of over 1, there are no problems (gaps, windows, etc.). Such old buildings reach values of over 10 in blower door tests, as I once read. Today’s new buildings, depending on wind, sometimes have a natural air exchange below 0.1 (blower door test usually below 1.0).

If you build without any kind of ventilation, then prepare to open windows for shock or cross ventilation at least 5 times a day, and that’s barely enough to avoid mold, but good air quality is gone an hour after the last ventilation.

At least take a central exhaust system with outdoor air inlets. But from there, it’s not far to controlled residential ventilation.

I’m not even in the planning phase yet, just reading up. I will probably change my opinion, we will see. My statement referred only to moisture. That the recommended air exchange rate can hardly be achieved by manual ventilation alone is clear to me. However, I think 0.3 is also easily sufficient there. Controlled residential ventilation achieves this value roughly even when operated at level 1, which many users do.

Good evening,

..., but together with proper cross-ventilation, there should be absolutely no moisture problems at all.

3 to at most 5 times a day - every day - for the first two years?

Besides, an estimated 80% build like this here (yes, I know that doesn't have to mean anything )

Because many builders save in the wrong places; sometimes it doesn't weigh as heavily though, because one partner is on parental leave and consequently runs through the house several times a day

I might also add a decentralized system like BluMartin.

Good choice; even though I would call it more of a hybrid than a decentralized system.

Happy New Year!