Negative coverage about solid wall insulation (SWI) risks deterring people from insulating the UK’s 8.5m solid-wall homes, which we need to do to meet targets for reducing greenhouse gas emissions, and also to install heat pumps efficiently (Almost all external insulation fitted under Tory scheme needs repair or replacing, report finds, 14 October).

True, SWI is a high-risk retrofit measure since poor-quality installs can have catastrophic outcomes, but we have known this for a decade at least – we need better-quality SWI and better training for installers.

Your report says: “Almost all the external insulation fitted under the previous government’s energy efficiency scheme was installed so poorly it will have to be repaired or replaced.” But Ofgem and the Department for Energy Security and Net Zero know of 60,000 SWI installs with government funding and wrote to all of them. However, only 5,900 of them responded – suggesting that only 10% thought that they had a problem.

The article cites the National Audit Office report, which confuses failure to meet PAS 2035 (a very tough standard for retrofit measures) with “defects”. Other research also shows that SWI is often installed well.

True, solid wall insulation can go very wrong. Like with roof repairs, poor workmanship or cutting corners can be very costly to correct. However, this is no reason to abandon solid wall insulation – just as it is no reason to abandon roof repairs.
Jason Palmer
Senior research fellow, UCL Energy Institute