24 cm Ytong + insulation or 36.5 cm Ytong

It also makes no energetic sense to apply thermal insulation from the outside only to heat the entire masonry.

What nonsense!

The highly praised glass wool in the air layer absorbs water and transfers it to the sand-lime brick masonry.

What water is it supposed to absorb? Glass wool absorbs nothing because it has no capillary action!

There are whole puddles behind the clinker on the Z foil.

Then the Z foil is not installed correctly!

The highly praised glass wool in the air layer

... does not belong there - the air layer is not called air layer for nothing. It can border an insulation layer but should not be filled with it (except by blowing in, since the air layer does not necessarily have to be "solid").

It also makes no energetic sense to apply the thermal insulation from the outside only to then heat the entire masonry.

What nonsense!

... has no business there – the air gap is not called air gap without reason. It can adjoin an insulation layer, but should not be filled with it (except by blowing in, because the air gap does not necessarily have to be "massive").

Well. What else is cavity insulation than an air gap filled with mineral wool?

On the topic of WDVS insulation. Yes, it is hazardous waste that most disposal companies no longer accept. The stuff is usually so low quality that you can watch it crumble; everything always has to be cheap. What most don't know is that these materials become liquid when heated and run down the walls. Temperatures as low as 50°C, which can be reached in Germany with direct sunlight and a dark facade, are enough. It is certainly a slow process and not visible, but it does happen. Furthermore, the insulation materials are not as durable as monolithics. Many building experts claim that they lose their insulating value after 20 years and become useless. And just as described, there are only disadvantages regarding constructive properties. You cannot attach anything or only with difficulty. If the child has once thrown a metal chip at the wall, the facade has a mark; once with the toy tractor at the corner - also a mark.

On the topic of WDVS insulation.

Just now we were still talking about two-shell masonry with cavity insulation, weren't we? Otherwise, I basically agree with you on the topic of WDVS.

What is cavity insulation other than an air layer filled with mineral wool?

Cavity insulation, precisely. That's not a bad thing, but it is something different. An air layer has a purpose; it was designed with something in mind. It can classically fulfill its purpose as a hollow layer, occasionally also with blown-in insulation materials that remain within it, i.e., that pass through it. If you revise your thinking and prefer to fill the space of the hollow layer solidly, you can repurpose the air layer. However, its old name then no longer makes sense, as air is virtually a constructive component of an air layer. Air is more than "nothing"; as a "cushion," it can serve a function.

In the current insulation craze, the earth is once again understood as flat; only solid matter is attributed defined properties. Where there is believed to be a need for retrofitting, insulation materials are introduced into former air layers. In common parlance, the name of the layer remains, even if the technical meaning is changed. In this respect, you may view it as nitpicking if I point out a difference there.

Those who installed air layers 20 or 30 years ago did not do so out of stupidity. Currently, other methods are in vogue; filling a former air layer does not always serve the intended purpose.