Is controlled residential ventilation necessary with expanded clay and KFW55?

Careful. Lefts of any kind are prohibited :-(

Just take a moment to think about what the developer is saying there. And dismiss the whole story as complete nonsense. Of course, it’s rubbish, what role should the masonry play. However, if you plan a pink toilet bowl, then the controlled residential ventilation can probably be omitted.

And then you think, "they know what they're doing". (to refer to the attic in the neighboring thread)

If we still insist on a controlled residential ventilation system, the additional costs are about €15,000 for the device (Pluggit) and €8,000 for raising the walls on the upper floor and the screed on the upper floor.

P.S.: I hope you are using the term builder incorrectly and mean a general contractor whom you can choose freely. Does this builder maybe only build with this one wall structure and only know the others by hearsay? I interpret "raising the walls" as complete ignorance regarding controlled residential ventilation (his ceiling supplier apparently cannot handle it, so he needs build-up height on the floor for the ducts, ergo he only knows controlled residential ventilation by hearsay as the central variant). Since according to your self-assessment your diagnosis is "slot ventilator or controlled residential ventilation, you definitely need one of them," I advise you to change the construction contractor. He obviously lacks competence. Or maybe several?

And then you think, "they know what they’re doing." (to point to the attic in the other thread)

Please tell me the post number, I couldn’t find it right now in the other thread of the original poster.

P.S.: I hope that you are using the term developer incorrectly and mean a general contractor, whom you can choose freely.

No, the term developer is correctly used. In this particular case, there is no option due to the property.

No, the term Bauträger is correctly chosen. There is no choice in this specific case due to the property.

Oh dear, I feel sorry for you. It's not nice when you have to hammer competence into a general contractor with an expert first. Then you have to take this general contractor because of the developer unfortunately, and make the best out of it: expanded clay is okay, ETICS is known not to be my favorite but there are worse things than that, and you apparently have to avoid central controlled residential ventilation with him. So I see the (in my opinion to be clarified by you personally due to the lack of absolute truths) trade-off as being whether you want RegelAir or decentralized controlled residential ventilation.

I see the (in my opinion, only to be clarified by you personally due to lack of absolute truths) trade-off as whether you want RegelAir or decentralized controlled residential ventilation.

I feared that. I can only partially come to terms with both variants.

With decentralized controlled residential ventilation, I have several core drillings in the insulation. Is heat recovery and filtering even possible with this variant?

With window rebate ventilation (Regel-Air), I have a certain discomfort cutting into the brand-new seals of the windows.