We have a passive-class house where the net heating requirement to keep the house warm in the coldest winter months is approximately 1kW.  The only heating system for doing this an underfloor heating (UFH) system base on 3 ~100m UFH loops buried in our passive slab.  That's it; no upper floor systems; no towel rails; nothing.  The reason for this is that our timber framed house is super insulated and air tight so there is very little temperature variation throughout the house, but that's all bee