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.
Ventilation of this property of 1 air change per hour will need far more than Andy has allowed
You might have a point there - I had attempted to include ventilation losses at 0.5 ACH (which I think is a pretty usual target), but had missed out one factor in that calculation ? Apologies I should have spotted that earlier (one of the danger of spreadsheets over manual calculation!). My revised figures now show about 4.5kW for ventilation and about 10.6kW overall. A large new build could well incorporate mechanical heat recovery ventilation though which should easily reduce the ventilation losses by more than 70% (at the expense of a few tens of watts for running the fans and controls). As before, insulation better than minimum building regs requirements could reduce the figures very substantially still.
Building technology has moved along quite substantially in the last 15 years or so - new builds are now incorporating levels of insulation that a generation ago were thought to be physically almost impossible and increasing fuel prices and likeley future fuel scarcity are making high levels of insulation more and more attractive, especially in the self-build sector (what will you run your gas boiler on once North Sea gas runs out?).
I would hope that a reasonably prestigious new build wouldn't think of installing tacky instantaneous electric showers either - they're really just a bodge to get around getting a decent shower out of traditional UK low pressure hot water systems and inefficient boilers - they're virtually unknown in much of the rest of the world where high pressure hot water has been standard for generations. If you are heating water by electricity then a storage system giving high pressure hot water and heated off-peak usually makes a lot more sense.
Ventilation of this property of 1 air change per hour will need far more than Andy has allowed
You might have a point there - I had attempted to include ventilation losses at 0.5 ACH (which I think is a pretty usual target), but had missed out one factor in that calculation ? Apologies I should have spotted that earlier (one of the danger of spreadsheets over manual calculation!). My revised figures now show about 4.5kW for ventilation and about 10.6kW overall. A large new build could well incorporate mechanical heat recovery ventilation though which should easily reduce the ventilation losses by more than 70% (at the expense of a few tens of watts for running the fans and controls). As before, insulation better than minimum building regs requirements could reduce the figures very substantially still.
Building technology has moved along quite substantially in the last 15 years or so - new builds are now incorporating levels of insulation that a generation ago were thought to be physically almost impossible and increasing fuel prices and likeley future fuel scarcity are making high levels of insulation more and more attractive, especially in the self-build sector (what will you run your gas boiler on once North Sea gas runs out?).
I would hope that a reasonably prestigious new build wouldn't think of installing tacky instantaneous electric showers either - they're really just a bodge to get around getting a decent shower out of traditional UK low pressure hot water systems and inefficient boilers - they're virtually unknown in much of the rest of the world where high pressure hot water has been standard for generations. If you are heating water by electricity then a storage system giving high pressure hot water and heated off-peak usually makes a lot more sense.
