Currently, two favorites have emerged: Gas +Controlled Residential Ventilation+ST might possibly be feasible after all, as well as the well heat pump.
For the latter, we will soon receive an offer from a respective company that has already built one at a distance of 200m.
: Thanks for your ideas. Unfortunately, our GCs do not seem to be very creative in this regard so far, or have not yet installed these. And intuitively, I would prefer to use something that at least our construction companies are already familiar with.