The government should enforce energy efficient building standards and tax those who don’t comply.
Forcing existing landlords to retrofit to new building standards isn't even done for safety purposes, so it certainly isn't going to happen for energy efficiency.
And calling for this to now be a thing, well, I can't think of a better way to get entrenched interests to suddenly lobby hard against every single new building reg.
No, but habitability standards do (or, technically, in general affect the legal ability to charge rent for units in existing buildings.) So, user those of your concern is recalcitrant landlords.
> Forcing existing landlords to retrofit to new building standards isn't even done for safety purposes
Yes, this is done (not always, but it does happen), through habitability standards beifn updated along with building standards (or referencing them.)
And the only example I can think of for the latter was for asbestos. If being as horrible as asbestos is the bar you have to clear, regulation isn't a viable option and we're stuck with market solutions.