@Appelmoesje @givenup Fridges do actually do better with small deltas. If you've ever done a grocery run at a beach condo, you'll know what I'm talking about. Most of the time a fridge is working against 60-80°F surrounding air. Geothermal heat pumps typically have COPs of 3 to 5, AKA 300-500% net efficiency. Ground water doesn't freeze in most habitable zones, so you just tap into that instead of trying to pull from the cold air. Some systems will actually run the water loop into the well to get more constant temps. Not trying to argue with you but geothermal is amm separate animal from hippy nonsense heat pumps.