The basic equation is ROI on insulation and other energy efficiency investment, which is directly dependent on energy prices. We know very well how to implement really good insulation (eg passive houses in -20C climates), heat recovery for ventilation, and non fossil heating sources. But fossil energy is too cheap and regulated incentives lacking to improve building energy efficiency.

Let's hope the EU policy in the works[1] will fix some of this and not get gutted by the anti-green populist factions.

[1] https://www.eceee.org/all-news/news/news-2021/new-report-epb...