[mjd89]

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).

[georgefrowny]

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.

[rsynnott]

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.

[blitzar]

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

[lm28469]

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