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I think you can also ensure a healthy indoor climate if you choose a wall construction that can absorb and release moisture, for example.

What should the wall construction then look like and where should the wall release the moisture if the house is airtight?

Hello, for example, certain building materials can have moisture-regulating effects... for example clay bricks or also sand-lime bricks... at least several experts in my circle of acquaintances have explained it to me that way. If the house is completely sealed on the outside, for example by an ETICS, that of course doesn't work. But if you use a diffusion-open insulation (cavity insulation), then the wall can "breathe" and still insulate.

Hello everyone,
so whether the operating costs are just laughable, I don't know.
After all, the ducts of a controlled residential ventilation system also need to be cleaned, right?

Yes, if you don't use filters. Otherwise, you might only need to clean them every 10 years or so...

I read in a report that a poorly maintained controlled residential ventilation system can become a real breeding ground for germs.

The purpose of the report was to make you believe that

Filters also need to be replaced quite frequently.
I do think you can quickly end up spending 200 - 300 € per year. Without electricity!

The costs are relative. One person signs a maintenance contract with a craftsman and has the filters replaced regularly by them. Another buys the filters and replaces them themselves. Yet another buys fabric by the meter, cuts it to size themselves, and also replaces the filters themselves. The costs vary here from a few euros up to a few hundred euros. There are, of course, no limits upwards and it depends on the client

I think you can also ensure a healthy indoor climate if you choose, for example, a wall construction that can absorb and release moisture.

The wall still needs to be invented. Usually, people who think that show up again a few years later with "little problems."

Hello,
for example, certain building materials can have moisture-regulating effects... for example, clay bricks or sand-lime bricks... at least that is what several experts in my circle of acquaintances have explained to me.

If the house is completely sealed to the outside, for example by an ETICS, that of course does not work. But if you use a diffusion-open insulation (core insulation), then the wall can "breathe" and still insulate.

The moisture that diffuses out through your clay and sand-lime bricks is in the per mille range of what occurs inside the house. You can only get rid of moisture by ventilation!!

Hello,
for example, certain building materials can have moisture-regulating effects... for example, clay bricks or sand-lime bricks... at least several experts in my circle of acquaintances have explained it to me that way.

If the house is completely sealed on the outside, for example by an ETICS, that of course doesn't work. But if you use a diffusion-open insulation (core insulation), then the wall can "breathe" and still provide insulation.

Unfortunately, the egg-laying wool-milk-sow has not been invented yet.

Certainly, the costs are relative, but nowadays you quickly lose the warranty if you don't take out a maintenance contract! So I do think that if you consider the building physics, you can manage quite well in a building without controlled residential ventilation. Unfortunately, it is often the case today that many general contractors/project managers do not pay attention to the performance of the building materials but to the price. Then, of course, you have to install controlled residential ventilation to remedy the situation. I have some acquaintances who have dealt with construction for many years (from civil engineers to architects to university professors for building construction) and almost all of them have told me that for our building project we can easily do without controlled residential ventilation... if we choose the right building materials. However, we will not build cheaper because of that!