It's not apples-to-apples though due to the difference in heating efficiency. If you use N kWh to heat your house with a gas boiler, you'll use N/P to heat it with a heat pump. P is something like 3 or 4, depending on various factors (and who you ask).

Plus housing insulation. So many British houses are still almost entirely uninsulated. That's not an exaggeration, the roof of my house had zero insulation, solid brick walls, no under floor insulation and single glazing. The only gesture to efficiency was some secondary glazing over the windows.

It absolutely ripped though gas just to keep a couple of rooms warm enough to live in, and it was still two jumpers and thermal trousers indoors. God only knows how the pensioner who lived there before managed.

Potentially bigger. There are a lot of old non-condenser boilers out there, with a typical efficiency of about 70%. And even condensers are often not much better than 75-80%; to hit the faceplate 90%+ efficiencies the system needs to be balanced such that the return temperature is in quite a narrow range.

I don't see many heat pumps in the wild - I do see plenty of resistive heaters and electric "power showers" still.

As long as they're powered by "clean" electricity it doesn't really matter though.

Depends on the context; if you are presently using x kWh of electricity for non-heating plus 2x kWh of gas for heating, your options for electrical heating are either to 3x your electricity demand by "upgrading" to resistive, or 1.5x (or whatever) your demand by upgrading to a heatpump.

There's other stuff you can also do, but costs are all over the place, e.g. my 110 ish sqm house in Berlin is so well insulated (and has heat pump) that even while it's snowing outside it's hot enough indoors to be naked, for an electricity bill that's lower than that of my 37 square meter apartment in the UK, despite German electricity prices being much higher.

Yep, just checked and my gas is just under double my electricity for 2025.

9,000kWh for electricity vs 16,000kWh for gas

That’s with charging an EV too.

If your gas boiler were replaced with a heat pump with an average COP of 4 it would only require around 4,000kWh of electricity to provide the same amount of heating.

Electric cars are similarly 3-4x more efficient than petrol cars on a kWh of fuel basis.

So while we should expect increased electricity demand as transport and heating are electrified, the increase in electricity usage will be far less than the decrease in kWh of fuel.

Sadly for me my gas is 1/4 the rate of electricity so it would cost the same. Ironically it’s the gas marginal rate that keeps the electricity cost high.

Rolling the heat pump into the overnight battery calculation could work to offset the cost of install of the heat pump but I can’t stomach the thought of replacing my radiators and pipes.