Looks like that trial's currently not accepting new participants, but thanks for the link - I'll keep an eye on it in case that changes.
The retrofit plan that an eco-retrofit architect is currently drawing up for me indicates that the biggest benefits are on the "windows=>triple-glazing" (3->2 tonnes Co2e/year) and "external-wall-insulation" (2->1.1 tonnes CO2e/year) steps, but I don't have cost data to establish a cost-benefit ratio for them yet. I'd always suggest that someone who's looking to make their house slightly more efficient start with good triple-glazed windows, though - single glazing and some types of older double glazing can be really surprisingly lossy. The airtightness and MVHR work is spread out among several stages, so is harder to analyse, but older houses leak like sieves and anywhere you can feel a breeze in the winter you can be fairly sure that you're paying to heat air that's escaping the house.
"What works best" is really a bit of a rabbithole. The standards I'm working to are here: https://aecb.net/aecb-retrofit-standard/ and the AECB site in general is full of information though it can be quite dense and jargonized. You may also find https://passivhaustrust.org.uk/news/detail/?nId=867 interesting - it's a report on retrofitting an entire block of flats by stripping and rebuilding the interior using /Internal/ Wall Insulation instead of the more common EWI - it's less popular because it can be a pest to do electrical and plumbing work around, but it's an option. The three strong pillars of eco-retrofit, at least as I've seen them to be so far, are airtightness (and ventilation!), wall insulation and triple-glazing, and competently made and installed glazing will be the easiest sell to the management company I imagine (if you don't already have it). The other two are more involved.
Thanks for the very comprehensive info. I think external wall insulation would be a hard one to get all the tenants to sign up for, but we're definitely due replacement windows in the next few years, so I'll push for triple glazing. Good luck with your retrofit!
The retrofit plan that an eco-retrofit architect is currently drawing up for me indicates that the biggest benefits are on the "windows=>triple-glazing" (3->2 tonnes Co2e/year) and "external-wall-insulation" (2->1.1 tonnes CO2e/year) steps, but I don't have cost data to establish a cost-benefit ratio for them yet. I'd always suggest that someone who's looking to make their house slightly more efficient start with good triple-glazed windows, though - single glazing and some types of older double glazing can be really surprisingly lossy. The airtightness and MVHR work is spread out among several stages, so is harder to analyse, but older houses leak like sieves and anywhere you can feel a breeze in the winter you can be fairly sure that you're paying to heat air that's escaping the house.
"What works best" is really a bit of a rabbithole. The standards I'm working to are here: https://aecb.net/aecb-retrofit-standard/ and the AECB site in general is full of information though it can be quite dense and jargonized. You may also find https://passivhaustrust.org.uk/news/detail/?nId=867 interesting - it's a report on retrofitting an entire block of flats by stripping and rebuilding the interior using /Internal/ Wall Insulation instead of the more common EWI - it's less popular because it can be a pest to do electrical and plumbing work around, but it's an option. The three strong pillars of eco-retrofit, at least as I've seen them to be so far, are airtightness (and ventilation!), wall insulation and triple-glazing, and competently made and installed glazing will be the easiest sell to the management company I imagine (if you don't already have it). The other two are more involved.