A scandal broke in October following a National Audit Office report showing that 98% of external wall insulation (EWI) fitted under the government ECO4 grant scheme has major problems. If not fixed, the householders will suffer from unhealthy damp and mould. This affected about 23,000 British homes of which over a thousand faced immediate health and safety risks. Internal Wall Insulation (IWI) had fewer defects with 27% of homes found to have major problems, but that’s still very bad for the people in those homes! ECO4 was a grant scheme, funded by the Energy Companies, for households on low income or with someone on benefits. An update last month from the Public Accounts Committee of MPs called for major system improvements and an investigation by the Serious Fraud Office into some of the companies involved.
These insulation problems were caused by bad installation. It was poorly supervised and badly managed at many levels. For example if rainwater gets in between the top of normal EWI and the wall, it can’t escape and soaks into the wall, making the inside damp and mouldy, resulting in a colder, unhealthy home. Good installations prevent this by protecting the top of the insulation with a roof extension or properly fitted aluminium capping. One victim of bad ECO4 work told BBC Radio 4 that the top of their EWI was waterproofed with tape!
I have more faith in the current Warm Homes Local Grant (WH:LG) scheme in Cambridgeshire, now including Peterborough, because it uses only 5 carefully vetted contractors, shown to have relevant expertise and qualifications. Some of their work is also independently assessed.
At Cambridge Carbon Footprint we notice from questions and comments that public trust in home energy improvements generally has been badly undermined by this scandalous bad work. We need more well trained installers working carefully for the right results.
Since 2010 Open Eco Homes (OEH) has showcased local exemplar homes with free in-person and online tours. We’ve featured 56 older homes, each with a Case Study giving details, including the installers for their energy efficiency measures. These include 40 homes with IWI or EWI that homeowners have been happy to show visitors. They find that well-installed insulation, draft proofing and heat pumps are brilliant for home comfort and cutting energy bills. With solar panels and batteries, where possible, these homes help tackle climate change and will be resilient into the future.
The photos here are of Kim and Charlie’s Cambridge 1930s home, fitted with EWI in 2015. It cost £9.4k, of which £6k was met by a grant from Action on Energy, Cambridgeshire. (2015 prices!) Later in 2015 they showed their home to visitors in OEH, including the Cambridge MP, Daniel Zeichner.
I love the benefits of EWI and SWI that we’ve had fitted over the years in our mid-terrace home. We recently completed this with IWI at the front, with none of the problems mentioned above. It also helps keep the home cool in heatwaves. Watch out for it in OEH this autumn.
By Tom Bragg, CCF volunteer
Shorter version published in The Cambridge Independent, 18/2/2026 as: “The benefits of wall insulation – when done well”