Oh that's interesting. What I've heard is that changing the heating system from radiators that use water heated by gas (as is common in German gas heating systems) to a heat pump is difficult because heat pumps don't give you such high temperatures. So you'd need a lot more surface area to heat adequately with the lower temperatures provided by your heat pump, i.e. you'd need to switch to underfloor heating, which means ripping open all your floors. Glad to hear that there are apparently simpler ways. We need to switch almost all buildings over to heat pumps over the next two or three decades after all.