I don’t know about “inaction”. Some of us, probably many…have taken sensible steps already, actually way before the current situation. Certainly we’ve worked on insulation and draft proofing, much was done 15 to 25 years ago. We were going to move a couple of years ago so I have a recent EPC report. We are D and could move to C with either external or internal insulation to the exterior walls. Exterior insulation is out of the question as this is a conservation area (not listed) so external cladding is not permitted. Interior insulation would I estimate cost £50k to £100k, the pure insulation costs would be a few £k, it’s fixing the the internal features and decor where the costs lie. The EPC suggests costs of £4K to £14k but this is just for cost of the additional insulation.
The house is a semi, it has 4 floors, 6 bedrooms, 4,000sq ft, 15 rooms/hall/landings/bathrooms to redecorate following the installation of internal insulation, reinstate Edwardian cornice, picture rail and skirtings.
The EPC doesn’t give us much credit for the roof insulation we installed. There’s 6 inches of the usual “wool” on the rafters and an inch of Kingspan under the breathable felt. This resulted in a huge improvement for keeping heat in and general comfort too. Previously heat rose through the house and out the roof.
I don’t believe there’s much more we can do to make a significant difference without spending serious money, the costs I foresee are in line with the Irish article.
edit…one recent improvement has been to a number of sash windows, double glazing them isn’t practical so we installed plantation shutters, these are very effective but of course need to closed so their impact is only at night.