Construction method: 36.5 cm aerated concrete or 17.5 cm + 14 cm external thermal insulation composite system (ETICS)

Folding ventilation means that where the profiles of the window frame and the window sash meet (and a gap is unavoidable in two dimensions), targeted channels for air flow are constructed. The window is thus quasi "intentionally leaky" to compensate for disadvantages of "too" good insulation. Simplified, this means making the insulation just imperfect enough so that it does not "cause harm."

Eine Frage hätte ich dann doch noch, macht es einen Unterschied wenn ich Blähton 15 - 20 cm mit WDVS wähle ?

Yes and no. Every stone has slightly different properties, but this does not change the fundamental decision between "stone" or "thinner stone plus ETICS."

So that means if I choose the thicker stone wall, a rebate ventilation in the windows is not necessary and simple ventilation is theoretically sufficient?

The insulation has nothing to do with the airtightness. Whether with or without [WDVS], some form of ventilation should be provided.

So if I choose the thicker stone wall, a rebate ventilation in the windows is not necessary and simple airing theoretically suffices?

I think it has already been said. Nowadays, buildings must be airtight, no matter what. It doesn’t matter whether with thick stone or thin stone, ETICS or monolithic, calcium silicate brick or cheap aerated concrete... it is and remains airtight.

The decision for or against a ventilation system or window rebate ventilators (which I also think are pretty stupid) therefore does not depend on the wall structure.. invest the money in a ventilation system, you won’t regret it. The living comfort increases enormously... always fresh air, after getting up, in the rooms of pubescent teenagers, with farting dogs, etc. And the annoying airing by opening windows disappears if you don’t feel like it.

Here worlds collide, Clash of Civilizations. With us, the bedroom window is at most ever closed during frost weather. The bathroom is always tilted open. And in the morning, the first thing is the terrace door in the kitchen open, and outside in any weather except deep snow a few squats in the t-shirt, then coffee and listening to the birds. And let the cat out, or in, if she was outside at night. Never, never would such an artificial ventilation system come into my house.

So the air from outside is artificial? Interesting... the quality is really getting better and better.