[ashayh]

Aero barrier and/or spray foam for an existing home should work well. But they are not long lasting and are often not environmentally friendly. You can also look into exterior insulation.

If possible and if you have the funds, try to do a retrofit: https://ekobuilt.com/2019/04/24/retrofitting-an-older-home-t...

https://www.buildwithrise.com/stories/passive-house-retrofit...

You don't have to do all the the things to improve performance -- you can pick and choose.