There are many assumptions in these numbers, and most of them are to do with cost, which is being minimised. If these were modern houses the heating requirement most of the time might well be low, say 3kW, but British weather being what it is we have snow and -20C temperatures (particularly up north or Scotland) much more often than is often realised. This means the heat pump will struggle and additional heating will also be needed. Then there are the electric vehicles, which if we all have one will need a great deal of charging power unless typical usage can also be controlled (which I hope it never can be). Then there is the cooker, washing machine etc. These figures have been pared to the absolute minimum, and I assume that load shedding will become common.

There are many assumptions in these numbers, and most of them are to do with cost, which is being minimised. If these were modern houses the heating requirement most of the time might well be low, say 3kW, but British weather being what it is we have snow and -20C temperatures (particularly up north or Scotland) much more often than is often realised. This means the heat pump will struggle and additional heating will also be needed. Then there are the electric vehicles, which if we all have one will need a great deal of charging power unless typical usage can also be controlled (which I hope it never can be). Then there is the cooker, washing machine etc. These figures have been pared to the absolute minimum, and I assume that load shedding will become common.