[aoner]

We ditched our gas and have an air to water heat pump, costed around €6000 ex subsidies (I live in Amsterdam so not the coldest weather, we also have solar thermal and PV).

However air to water heat pumps are also applicable in cold climates. If you're interested here is an example datasheet[1] of an air to water heat pump (2018) (using Celsius here):

Mitsubishi PUHZ-SHW112YAA Guaranteed operating range (outdoor): Heating: -28 to +21 Domestic hot water: -28 to +35

On page 108 you can find the actual co-efficient of performance (COP) for different outside temperatures and inside water heating temperatures. As an example: at -10 and an water temperature for heating at 25 you still get a COP of 3+. That means that 100% electricity moves 300% of heat into your house.

[1]: https://www.mitsubishi-les.info/database/servicemanual/files...