Masonry from Ytong 24 or 30 for single-family house?

Is that a typo or do you actually mean 42.5?
I wouldn't have expected any compromises regarding sound insulation here.

No, we have a 42.5 external wall (Lambda 0.08) with a U-value of 0.18 W/m2K. We are very satisfied. Sound insulation could be better, but we live on a play street, so there is not much going on.

Regards

No, we have 42.5 cm exterior walls (Lambda 0.08) with a U-value of 0.18 W/m2K. We are very satisfied. Sound insulation could be better, but we live on a play street, so there isn’t much going on.

Regards

We built with 0.07 Ytong at the aforementioned city/country and 36.5 cm. U-value 0.21.
Sound insulation is really important for the garden because of the decentralized ventilation holes in the walls. Well, it’s not really that loud here, it could be much worse.
With a child, the sources of noise are now more inside, haha.
We don’t have damp walls either. By the way, KFW55. Back then still gas/solar hot water – meanwhile, a 4-split air conditioning system, i.e. air-to-air heat pump, has been added. Perfect for temperatures around 0-10 degrees like now. In summer too, of course. Ytong hardly stores any heat/cold and the screed is also decoupled because of underfloor heating. In the home office, it often gets up to 26 degrees or more by noon.

For air heat pumps, one should not exceed a wall U-value of 0.20 W/m2K. This is not without reason the recommendation in the BEG, and the building energy law will still adjust accordingly if Germany now wants more heat pumps in residential construction. The SCOP values and crucial annual performance factor values are simply too poor given the rising electricity costs.

The disadvantage of aerated concrete is component activation as a buffer and storage mass. Every sand-lime brick with 17.5 plus ETICS is unbeatable there.

In Germany, the cooling load is becoming increasingly important compared to the heating load. Simply enter the location at the Federal Heat Pump Association and then see how many annual hours at which temperatures occur.

For those who don’t find it right away: Climate map under Norms and Technology and then enter the ZIP code there - Cool thing

And here you can also see whether the correct standard temperature was assumed for the static heating load calculation according to DIN 12831 at all.

Phew. When I look at all the things that can go wrong with ETICS, there are some great YouTube series by experts. I'm quite happy with a 36.5 cm aerated concrete wall, even if it "only" has 0.23 as a U-value.

This U-value nonsense for masonry is ridiculous anyway, beyond a certain point. The windows, which make up about 1/5 of the facade area, lose more heat than the masonry, with a U-value of 0.23.

That means a 10% lower U-value does not save 10% energy, but only 5%. If you don't consider the floor slab and the roof, a lot of energy is lost there too.

Therefore, the notion that a wall needs 0.2 or less for a heat pump is nonsense. The entire thermal envelope must be considered.

By the way, for those who complain about the load-bearing capacity of aerated concrete, I wish them good luck when they want to install an awning or a somewhat heavier lamp on their ETICS facade someday. Then you can talk about load-bearing capacities. But not with aerated concrete.
You just glue in wall anchors and that's it.

As if that Poroton stuff with its countless tiny air chambers holds better. Once you drill in with a hammer drill, the brick inside is just rubble. And then? Glue? Wall anchors? Where should it grab hold? In the brick dust?