Well with all these cold houses there's really no need for taking off jackets, so, win win 😉
I wish the Other stories bomber was cropped, then it would work well for me as a blazer of sorts indoors. Speaking of cropped jackets, I'm desperately in lust with this one, despite usually being allergic to sequins. The price is putting me off aside from probably not having too many occasions to wear it (but I'm convinced it can be worn casually).
I don't know what it's like in other countries, but as all homes here are sold with energy certificates there tend to be a lot of engineering companies specialised in making assessments and advising what's sensible to improve energy ratings. It's not my area of expertise and since each home is different they're the best to consult IME. Industry does still tend to lean to advising impermeable solutions as the efficiency is higher and the cost is lower and it's not necessarily bad, but risk of major issues are higher if something isn't done right somewhere along the way. It might be worth waiting a few years for permeable solutions to catch up in terms of price/efficiency if you're not in a hurry. The manufacturers of some permeable solutions also are able to give good advice, they'll engage with consumers even if they don't sell to them and can often direct you to reliable people to engage with.
Extensions always tend to be on the colder side as they're single story rooms with usually at least two outer walls, and if they placed any insulation in the 90s it probably had deteriorated with time to the point it was probably as good as useless. You end up with that weird effect you sometimes get with unheated toilet blocks at service stations that seem to be colder inside than out as they're just radiating cold from all surfaces.