Here is a more detailed description of my assumptions: I assume that today we use 30 kWh/d/p on making hot air and 10 kWh/d/p on hot water (including cooking). I assume that by insulating buildings we reduce the heat loss so that the heat required for hot air is reduced from 30 to 20. I assume that this 20 is delivered by 5 from wood and 15 from heat pumps, of which 5 was originally electricity and 10 was "free" pumped heat. As for the hot water (still 10) I assume that this 10 comes from solar HW (1); heat pump (4, of which 2 comes from electricity and 2 comes from "free" pumped heat), and 5 units of plain electricity (electric water heaters, electric hobs and electric ovens, for example). The total electricity required is thus 5+2+5=12. The amount of (free) pumped heat is 10+2=12. With 1 unit of solar and 5 of wood, we end up with 30 units of heat delivered to our buildings.