The standard supply for a new house seems to be circa 18KVA single-phase. I have a client who needs to make application for a supply for a new build house at 400m2 with the only certain information being that an air source heat pump is to be used for heating. The client simply does not know what the electrical loading might be. The house is only coming out of the foundations but the DNO supply may take many months as the house is in a relatively remote rural location, thus loading details are required before the DNO will consider progressing the proposal. It is a big house, but that is what it is, just a big house. I am inclined to advise a standard supply but 3-phase as with a large AS heat pump, maybe shower, cooking and perhaps an EV or two, 18KVA wouldn't be long being gobbled up. As we move towards a higher reliance on electric as a power source for some heavy current-using equipment, it might be that 18KVA is no longer a realistic standard supply for even the smaller property.
Even with good insulation 400 square meters would probably require at least a 24Kw gas boiler, or say 12 Kw of electricity for a heat pump.
I reckon that's rather pessimistic. I've done some very rough heat loss calculations for a 400m² building (with a lot of assumptions and guesses of course) based on some L1A U values (0.3 for walls, 2 for windows etc), and come out with a figure of less than 6.4kW total for -5 degrees outside. If it's a self-build for someone interested in keeping their running costs down, insulating to something closer to PasivHaus standard could half that figure. That's just space heating so add a bit for DHW of course - but it's still a lot less than 12kW never mind 24kW.
Even with good insulation 400 square meters would probably require at least a 24Kw gas boiler, or say 12 Kw of electricity for a heat pump.
I reckon that's rather pessimistic. I've done some very rough heat loss calculations for a 400m² building (with a lot of assumptions and guesses of course) based on some L1A U values (0.3 for walls, 2 for windows etc), and come out with a figure of less than 6.4kW total for -5 degrees outside. If it's a self-build for someone interested in keeping their running costs down, insulating to something closer to PasivHaus standard could half that figure. That's just space heating so add a bit for DHW of course - but it's still a lot less than 12kW never mind 24kW.
