Comment by altered_state

Yep that is a good solution that is popular as far as I've read. I've tried this as well initially but in my case this didn't work out due to the fact that the heat pump is too powerful for the house (about a factor of 2). And due to how slow the underfloor heating responds, I get huge overshoots when I use a controller like that.

So I had to figure out a way to switch it off earlier than reaching the setpoint, which lead to my poor man's solution of just calculating the house's heat loss.