Construction costs are currently skyrocketing

Insulation measures in existing buildings are usually a money-losing business without strong subsidies; making them mandatory is socially unfair and also ecologically questionable

Do you mean economically? Ecologically, insulation is absolutely sensible; it saves many times the amount of oil used. I have something between 10-20 times in mind, but don’t hold me to the exact number.

The obligation to carry out energy-related renovations within 2 years after acquisition has actually existed for a long time… it's just that nobody monitors it…

Simply nationalize energy completely, that is supply, production, consumption, but also renovation measures. Then there will at most be disputes about quotas (who is allowed to consume how much). But then you can choose accordingly.

The obligation to energetically renovate something within 2 years after acquisition has actually existed for a long time

Although I would not call that "renovation," but rather cosmetic retouching. What needs to be done? - Insulate uninsulated pipes in unheated rooms - Insulate roof/top floor ceiling if the minimum thermal protection is not given - Replace heating if too old – although this expressly does not apply to low-temperature or condensing units In the end, it’s trivial and actually only rarely done completely. And I have indeed never seen an inspection – because no one (chimney sweep) gets paid for the inspection, so no one is motivated.

That's exactly right! There was once an inquiry to the responsible ministries of the states about how often this was checked. Most did not respond, in BaWü it was apparently 6(!) transfers of ownership. In other words: Laws and regulations must be put into practice, otherwise they are useless.

We are now getting things moving with the EU renovation. Among other things, a narrow wall is supposed to be demolished and then re-erected in a different position. A structural engineer is coming at the beginning of January. Are there any comparable values here, has anyone had something like this done and still remembers how much the structural engineer cost?

I am also extremely curious about the estimate from the interior fitter, as quite a bit is supposed to be done. Mainly interior plaster, floor insulation, underfloor heating, screed, and a few small things.