Construction report single-family house 1200 €/m²

The energy source would first have to provide a high temperature, which is then artificially lowered again for the underfloor heating --> efficiency down the drain ;)

That's exactly how it is.

..The usually installed underfloor heating is a low-temperature system (due to energy efficiency), which is not compatible with the water-carrying towel radiator. This usually requires a significantly higher supply temperature.

And then what does the underfloor heating heat with: raspberry juice, aloe vera gel, ...???

We don't have this issue here for the first time either.

In a heating circuit, it's doubly bad because usually the water gets dirty due to the corrosion of the radiators, which is bad for underfloor heating.

Basically not so great, because as mentioned, radiators require a higher flow temperature. With gas, maybe not so dramatic because it already has higher system temperatures, but with a heat pump it's not elegant at all because then the heat pump has to provide flow temperatures of 40-50 degrees just because of the radiators, even though the underfloor heating is content with 35 degrees or even significantly less.

Where does the hot water for showering, etc., come from when using a heat pump?

Where does the hot water for showering etc. come from when using a heat pump then?

The heat pump temporarily produces higher temperatures for separate DHW charging.

That doesn't mean it can't do it... it just becomes inefficient then.

Bathroom and toilet on the ground floor because these are the two critical rooms with the highest ratio of heating load to floor area.

Water-carrying towel radiators have no place in new buildings anymore.

How does wall heating work? Are the pipes of the underfloor heating just laid closer together to heat the wall? What build-up height is needed approximately?