I also think a [Luft-Wasser-Wärmepumpe] would definitely be the better choice... the fact that underfloor heating needs to be installed in the house is basically beyond question.
I also think an air-to-water heat pump would definitely be the better choice...it is basically undisputed that underfloor heating has to be installed in the house.
What would be the advantage compared to the Lulu? Upon inquiry, it was said back then that with the new underfloor heating you wouldn't really feel the heat anymore.
We are unsure whether we should go back to KFW 55. hmm..
It probably won't be the basement. The additional 50,000 are simply not feasible.
Yes, nowadays with very low supply temperatures and, for example, at 30°C, the underfloor heating is at best only "lukewarm". An underfloor heating system works with radiant heat, so even lower temperatures feel sufficient. 21°C with underfloor heating feels just as warm as 24°C with air heating. Just search on Google, there are many examples and information.
The advantage is precisely the efficiency... if I were to suggest heating your house with air conditioning split systems... you would tell me I am probably not quite right and that it would be too expensive... but the air-to-air heat pump is nothing else...