> I think these challenges will get better over time but that is probably why governments aren't keen to make large improvements in energy-efficiency regulations.

This is probably true but it's still backwards. The state should want to improve the affordability of housing and should consult with industry on which measures can be introduced but ultimately the state must introduce the new regulations to help drive the market in the direction of continuous improvements to the housing stock's long-term affordability. I think if they shirk this then they simply aren't doing the job properly.