Ytong Energy Saving Regulation 25cm stone thickness allowed - Who has experience?

I can't tell you exactly. But our consumption is within a fairly normal range...

Why would one need more hot water?? Heating certainly to some extent more, but hot water?

No, of course you don't need more hot water than with thicker walls :)

Thank you for the answers, but here you can see the problem: The suppliers for Ytongg preferably want to sell the most expensive products! "Nordlys" writes that he got it through with 30s. "hemali" managed it with 24s, so it must be possible or was her hut torn down and is she now homeless? "Scout" -> No 25s (thanks for the heating tip regarding the existing building) It is under 50m², -- that is why the battle for centimeters. "dertill" says precisely that 0.24W/m²K must absolutely be adhered to, and therefore 24s are not possible. ---- I will research the values of the stones. The costs mentioned by "Nutshell" are never really comparable, because not only the number of people matters, but also the individual lifestyles. With my 25 stones (of course normally plastered) I have lived happily for a long time and have not noticed any big differences in rough comparisons with other houses. In autumn and winter I also put on a sweater and turn down the less used rooms. As a "born cave dweller," I also shower only once a day. (yuck) :-) Of course, I have also thought about putting styrofoam outside, but the researched costs, if not "nicely calculated," have prompted me to rather think about a heat pump. (still considering, since it’s also complicated (air/water/deep drilling/shallow drilling — I will see if there is info about this here in the forum) Maybe I’ll slap styrofoam on the planned new build later, it’s not that big, but because of the boundary distance and built-up area I have to stay "small" first, as every m² counts. For this reason, I would prefer to use the 25 stones. But if it really doesn’t work, I don’t need to invest the effort in drawing and calculation if I’d have to change it afterwards. --- Which authority actually checks compliance, is it checked at all, might it differ in the (federal) states? Sorry for the questions — 20 years ago this was all simpler — Ytongg said take our 25s, — submitted, ticked off, built, and done. No wonder everything is getting more expensive! So first of all thank you, I will now get information about the stones. Back then, there weren’t so many either. Was everything really better in the past? ;-)

We built according to the Energy Saving Ordinance 2016 and with our very large, well-known main contractor it is standard. If that were not possible, it would have been noticed long ago! We had the plans checked in advance by the building expert and later explicitly asked him again whether that could be problematic. The statement was very clear: "No, it can be done"!

We built according to the Energy Saving Ordinance 2016 and with our very large, well-known general contractor it is standard.

24 cm aerated concrete with a lambda value of 0.09 W/mK results in a U-value of approximately 0.35 W/m²K

If you meet the Energy Saving Ordinance in new buildings through other better insulated components – congratulations. However, this is not possible in existing buildings, as Table 1 from Annex 3.7 of the Energy Saving Ordinance 2014 applies here. And that prescribes a U-value for exterior walls less than 0.24, i.e. 365 mm at lambda 0.09, if no additional layers (except plaster) are added. I am not aware of better insulating aerated concrete.

Regarding control, as far as I know, the authorized applicants for building permits are responsible for checking compliance with the Energy Saving Ordinance. Whether this is mandatory and whether they have to intervene there, I do not know. The whole thing is still quite uncontrolled, especially in existing buildings (for example, who checks the insulation thickness of the facade insulation I installed myself). As far as I know, it looks different when submitting a building application. Please correct me if I am wrong!

Energy Saving Ordinance, renovation of existing buildings, max 50 sqm without new heating: orientation to the existing building. Can be googled: Energy Saving Ordinance 2016 extension under 50 sqm