Select Committee · Public Accounts Committee

Faulty energy efficiency installations

Status: Open Opened: 10 Jul 2025 19 recommendations 20 conclusions 1 report

The Energy Company Obligation 4 (ECO4) and the Great British Insulation Scheme (GBIS), both funded via energy consumers’ bills, are government schemes for the installation of energy-efficiency improvements in people’s homes, such as insulation. Not-for-profit quality assurance company TrustMark identified issues with both schemes, with government announcing in January 2025 issues including insufficient ventilation, missing …

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Reports

1 report
Title HC No. Published Items Response
62nd Report - Faulty energy efficiency installations HC 1229 23 Jan 2026 39 Responded

Recommendations & Conclusions

12 items
13 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Installer suspension and reinstatement process insufficient for widespread insulation failures

To limit further faulty installations, the Department asked the certification bodies and scheme providers, via TrustMark, to suspend installer businesses based on their failure rate. By the end of January 2025, 38 installers had been suspended, preventing them from carrying out new work of this kind under government schemes.22 The …

Government response. The response addresses a different recommendation regarding a blanket ban on external/internal wall insulation installations, not the specific issues raised in this conclusion about the suspension and reinstatement of installers.
HM Treasury
15 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Delays in fixing faulty installations increase property damage and health risks

Delays in finding and fixing these homes increase the risk of damage to the property, including damp and mould, and leave people in homes with unaddressed health and safety risks.29 We asked the witnesses how they would make sure the remaining faulty installations would be found and fixed in a …

Government response. The response addresses a different recommendation regarding a blanket ban on external/internal wall insulation installations, not the specific issues raised in this conclusion about delays in finding and fixing faulty installations.
HM Treasury
16 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Provide regular six-monthly updates to the Committee on external wall insulation remediation progress.

The Department and TrustMark told us that TrustMark would oversee a find-and-fix process for homes with external wall insulation. It would offer audits to all homes with external wall insulation installed through ECO4 or GBIS, provide direct oversight to ensure the work is corrected, and work with local communities to …

Government response. The response addresses a different recommendation regarding a blanket ban on external/internal wall insulation installations, not the specific issues raised in this conclusion about the TrustMark find-and-fix process and optimistic timescales.
HM Treasury
17 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Current plans for identifying faulty internal wall insulation lack proactive detection of hidden defects.

The Department told us that it plans to identify faulty internal wall insulation through existing audit processes. First, TrustMark and the certification bodies continue to conduct business-as-usual audits. Second, households with concerns can contact their installer and certification body, or the ECO contact centre run by Ofgem, through which calls …

Government response. The response addresses a different recommendation regarding a blanket ban on external/internal wall insulation installations, not the specific issues raised in this conclusion about identifying faulty internal wall insulation.
HM Treasury
18 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

TrustMark's registration process fails to adequately assess installer businesses' financial stability and liquidity.

The original installer is liable for fixing the installation to meet the relevant standards. However, the National Audit Office reported that not all installers are complying with the remediation process.38 We asked TrustMark whether the process for installer businesses to become TrustMark-registered (and therefore be able to do work under …

Government response. The response addresses a different recommendation regarding a blanket ban on external/internal wall insulation installations, not the specific issues raised in this conclusion about the financial stability of installer businesses.
HM Treasury
20 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Households lack trust in original installers for defect repairs, despite Departmental competency assurances.

Written evidence submitted to us by the Green Homes Group highlighted how some people are unlikely to trust the original installer to fix the issues they created.42 The Department said it is providing assurance to households by ensuring the installer is appropriately certified as competent to do the work, and …

Government response. The government states that all EWI and IWI measures installed under ECO4 and GBIS schemes should have a guarantee that lasts for 25 years.
HM Treasury
21 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Guarantees cover remediation costs up to £20,000, excluding compensation for health issues.

If the installer has ceased to trade or fails to fix the issues, remediation costs up to £20,000 should be covered by a guarantee.44 TrustMark confirmed in follow-up correspondence that these policies do not cover compensation for ill health or loss of earnings that might arise as a consequence of …

Government response. The government states that all EWI and IWI measures installed under ECO4 and GBIS schemes should have a guarantee that lasts for 25 years.
HM Treasury
22 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

The guarantee market for solid wall insulation is notably limited to only three providers.

TrustMark told us that three organisations provided the bulk of the cover.47 In written evidence provided after the oral evidence session, the Department confirmed that the guarantee market for solid wall insulation is limited to three companies: QualityMark Protection, which provides regulated insurance-backed guarantees through SafeWorld; and SWIGA and CIGA/IAA, …

Government response. The government states that all EWI and IWI measures installed under ECO4 and GBIS schemes should have a guarantee that lasts for 25 years.
HM Treasury
23 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Guarantee invocation processes are complex and lengthy, delaying resolution of serious defects.

We asked the witnesses whether they had analysed the guarantee policy wording to ensure they did not include excesses or complex issues that render them useless in practice, or had reviewed the balance sheets of the 39 Q 64 40 C&AG’s Report, para 16 41 Qq 59, 60 42 FEE023 …

Government response. The government states that all EWI and IWI measures installed under ECO4 and GBIS schemes should have a guarantee that lasts for 25 years.
HM Treasury
24 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Remediation costs for severe installation defects can significantly exceed the £20,000 guarantee limit.

Where guarantees are invoked, the repairs will likely in some cases cost more than the £20,000 covered by guarantee. TrustMark advises it should normally cost between £250 and £18,000 per home to correct the faulty installations, if it can be done before major damage occurs. However, in the worst case …

Government response. The government states that all EWI and IWI measures installed under ECO4 and GBIS schemes should have a guarantee that lasts for 25 years.
HM Treasury
31 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Department acknowledges current quality assurance system is too layered and fragmented.

The Department told us it designed the consumer protection and quality assurance system in response to the 2016 Each Home Counts review, introducing a single quality mark (delivered by TrustMark) and higher standards that consider multi-measure retrofits in the context of the whole home.69 It told us that the new …

Government response. The response addresses a different recommendation, regarding an annual report on retrofit schemes, and not the conclusion about the complex consumer protection and quality assurance system.
HM Treasury
32 Conclusion 62nd Report - Faulty energy efficiency … Not Addressed

Organisations within the system failed to adequately warn Department about risks and flaws.

We asked the witnesses why no-one warned the Department about the risks or flaws with the system it had designed, or considered whether the system as a whole was protecting consumers.72 While TrustMark accepted it should have done much more, Ofgem highlighted their limited role within the flawed system. • …

Government response. The response addresses a different recommendation, regarding an annual report on retrofit schemes, and not the conclusion about lack of warnings about the risks or flaws of the system.
HM Treasury

Oral evidence sessions

1 session
Date Witnesses
13 Nov 2025 Clive Maxwell CB CBE · Department for Energy Security and Net Zero, Deborah Chittenden · Department for Energy Security and Net Zero, Jeremy Pocklington CB · Ministry of Defence, Jonathan Brearley · Department for Energy Security and Net Zero, Jonathan Brearley · Ofgem, Kiera Schoenemann · Ofgem, Matt Gantley · United Kingdom Accreditation Service (UKAS), Simon Ayers MBE · TrustMark View ↗

Correspondence

6 letters
DateDirectionTitle
21 May 2026 From cttee Letter to the Permanent Secretary at the Department for Energy Security and Net…
23 Feb 2026 To cttee Letter from the Interim Permanent Secretary at the Department for Energy Securi…
12 Jan 2026 To cttee Letter from the Chief Executive Officer of the Installation Assurance Authority…
8 Dec 2025 To cttee Letter from the Chief Executive of the UK Accreditation Service relating to the…
8 Dec 2025 To cttee Letter from the Interim Permanent Secretary at the Department for Energy Securi…
1 Dec 2025 To cttee Letter from the Chief Operating Officer at TrustMark relating to the Committee’…