This would be more convincing a reason if the new builds over the last couple of decades had been fitted with good insulation and heat pumps. Since they dragge

This would be more convincing a reason if the new builds over the last couple of decades had been fitted with good insulation and heat pumps. Since they dragged their heels on that low hanging fruit, I'll suggest they've not really even tried to make it work elsewhere. (There have been some improvements so I don't want to get carried away, but there's also estimates of many Billions wasted by not doing what was obviously a good idea at the time). Also, recent real world experience suggests more older buildings than you think will work. Britain doesn't get that cold for that long and modern heatpumps and insulation techniques are pretty good.