Heat pump is air conditioner

[Everyone]

Air vents should be able to both cool and warm - powered by heat pump (both cool and warm) or AC (just cool).
Radiators should not be powered by a heat pump.
Heat pump might have a downside of being less efficient when it's bellow -15C or so.

It's more intuitive to when game does not invent new physics, especially when the result does not matter much (place things and forget).