IIRC this flawed arrangement is in common with Japan, and often leads to sick notes made for days or more just to make sure the patient doesn’t have to go get one sick leave note per day, meaning unexpected vacations, commonly.
So already knowing how that works, is this just performative politics by Merz?
A working link / definition of a ground-source, residential heat pump might help. WP has a page: https://en.wikipedia.org/wiki/Ground_source_heat_pump
I guess followup Q’s would be like: how practical are they across Europe?, what types of situations would they work best work in and where might they be impractical? How much can they scale to larger buildings?