Aerated concrete exterior wall vs. Energy Saving Ordinance

They don’t build pure 24 aerated concrete.... either double-shell or ETICS.... and that’s how it will be with your BT as well – otherwise it (practically) doesn’t work. I can only agree with oleda regarding ST.

24' Ytong without ETICS definitely no longer meets the Energy Saving Ordinance. A pure 24' Ytong wall construction with triple glazing does not match. The masonry must fit the windows and vice versa, otherwise the humidity condenses on the walls. The architect's statement is questionable.

I know about something like that too.. we had an architect who said you don’t need controlled residential ventilation because the house breathes... at first I thought he was crazy. But then we visited some of his projects and talked to the owners – they really didn’t have any air quality problems. A lot of wood, lime plaster, and clay plaster etc. pp. were installed.
He also mentioned one detail – the windows are not foamed in, but stuffed with jute (?).
In the end, we asked about the heating costs:
Building from 2005, 180 sqm (15 cm perlite insulation ~0.22 W/m²K, 20 cm isofloc in the roof ~0.19 W/m²K) -> 1800 € heating costs p.a.
Building from 2006, 110 sqm (15 cm perlite insulation ~0.22 W/m²K, 20 cm isofloc in the roof ~0.19 W/m²K) -> 1200 € heating costs p.a.

User behavior aside... the heating costs - gas - do say quite a bit about the breathing. Either the inhabitants ventilate a lot or there are drafts... (don’t get me wrong – the houses were beautiful and individual)

These heating costs were achieved with double glazing from 1975, aluminum frames without insulation in the frame, and 30 cm pumice without ETICS on 240 sqm. Old building with partial basement on a slope from 1964. However, without hot water. But exactly old building uninsulated! It was also individually built.

What reason is there for 24 cm aerated concrete walls? The extra cost compared to 36 cm walls should not be too high, but the insulation value is much better. I have also never heard of houses being built with 24 cm aerated concrete.

I myself will build (have built) with 36 cm aerated concrete. I even considered 42 cm walls for a time...

-.- as an inner shell or with [WDVS] that is not so far-fetched.