For a while after that, the government funded insulation top-ups in order to get an impressive sounding number of installs they could brag about, but those had much worse return on investment and that program was killed off a few years later. The thing is that we have an election coming up and a lot of the British press want the party that was in power back then and still is to lose, so they've pushed the narrative that cancelled insulation program would've achieved a lot more than it could've in reality and that people would've been saved from high energy bills if the government hadn't cancelled it for being too woke. There's been similar nonsense about other things like onshore wind for the same reason.

Anyway, at least in the UK the problem is that almost all of the easy, high-return on investment insulation upgrades have been done, and the only way to have a substantial impact is through ones that have payback times in the decades. If the era of zero interest rates is over permanently, that's basically equivalent to saying they'll never pay back the cost in many cases.