OK, it's almost a passive house, so needs very little in the way of heating. It's heavily insulated all the way round, in the case of the walls the construction is part of the insulation (40mm fibreboard externally, then 140mm I beam filled with warmcel, then 18mm OSB). The whole thing is extremely airtight, airflow is controlled via a whole house MVHR system. We have a small gas boiler running a very low temp underfloor heating system (cuts out at screed temp of 27C) and in one room (the posh one for mums and dads) we've got the lowest rated woodburner we could find (old parents like a visible heat source).

I don't know if we'll ever need to run the heating, it's been warmer in there since December with no heating than our existing house with heating on.

Lighting is mostly LED with some CFLs