[Valgrim]

The source of heating is not what's the most important (in any case an (electrical) heat pump is always going to be more energy efficient, everything else pales in comparison).

Insulation is really the most important thing to reduce a building energy consumption (some buildings are even built with zero heating: https://en.wikipedia.org/wiki/Zero_heating_building), along with air-tightness and heat_recovery_ventilation.

[brtkdotse]

Seriously. Modern insulation + heat pump/heat recovery ventilation makes it possible to heat a 140m2 house in the far north of Sweden for a whole year with a few thousand kWh.