Great British Insulation Scheme

Scheme status and closure details were checked on 22 July 2026. Historical budgets, delivery and remediation figures retain the date stated with them.

The Great British Insulation Scheme (GBIS) funded a single insulation measure in some of the least energy-efficient homes in Great Britain. Ofgem ran it on behalf of the Department for Energy Security and Net Zero (DESNZ). It was announced in March 2023, launched the following month and closed to new installations on 31 March 2026. In legislation it is ECO4A, a strand of the Energy Company Obligation (ECO) that ran alongside the main ECO4 scheme, and it was first trailed under the name ECO+. The three-year budget was £1 billion, and the aim was to improve the least efficient homes to help cut bills and tackle fuel poverty.

Eligibility: the general group and the low-income group

GBIS split applicants into two groups.

The general group covered a property with an Energy Performance Certificate (EPC) rating of D to G that sat in council tax bands A to D in England, or A to E in Scotland and Wales. A home in this group could get one insulation measure and might have to pay something towards the cost.

The low-income group covered households receiving qualifying benefits, such as Universal Credit, Pension Credit, Child Benefit, Housing Benefit or income-related Employment and Support Allowance. This group could get insulation plus secondary heating controls, and could receive more than one measure.

Local authorities could also refer low-income, fuel-poor or vulnerable households through flexible eligibility, known as Flex. Around 8,000 measures had been delivered through Flex by August 2025. Social housing in EPC band E, F or G qualified for measures; band D social housing qualified for innovation measures only.

Insulation measures and heating controls

The scheme funded nine primary insulation measures: cavity wall insulation including party walls, loft insulation, solid wall insulation (external, internal or hybrid), room-in-roof insulation, pitched roof insulation, flat roof insulation, underfloor insulation, solid floor insulation and park home insulation.

The low-income group could also get secondary heating controls, such as thermostatic radiator valves (TRVs), a boiler programmer and a room thermostat.

Changes announced in June 2025 loosened the single-measure limit. Homes could then receive up to two insulation measures, smart thermostats were added for owner-occupied low-income households, and obligated suppliers were allowed to move some of their ECO4 delivery towards the GBIS target.

Work was meant to meet the retrofit standards PAS 2030 and PAS 2035 and be carried out by a TrustMark-registered installer. From 1 April 2025 the required versions were PAS 2030:2023 and PAS 2035:2023. Unlike ECO4, GBIS set no minimum improvement in a home’s Standard Assessment Procedure (SAP) rating.

Delivery against the 300,000-home target

The scheme was expected to treat around 300,000 homes, with published targets ranging from roughly 300,000 to 315,000. Delivery came in well below that. By August 2025, 102,200 measures had been installed across 78,600 households, and 66,400 of those households had received only one measure. Cavity wall insulation was the most common measure at 40%, followed by loft insulation at 28% and heating controls at 22%. About half the measures went to the low-income group.

A treated home was estimated to save £300 to £400 a year on energy bills, and the scheme was expected to cut non-traded greenhouse gas emissions by 0.65 million tonnes of carbon dioxide equivalent.

The 2025 National Audit Office findings on wall insulation

In October 2025 the National Audit Office (NAO) reported serious quality problems with wall insulation installed under ECO4 and GBIS. It found that 98% of external wall insulation (EWI) installations needed repair, affecting an estimated 22,000 to 23,000 homes, and that 29% of internal wall insulation (IWI) installations had major issues, affecting 9,000 to 13,000 homes. About 6% of EWI installations, roughly 3,000, posed an immediate health and safety risk. Common faults included insufficient ventilation, missing or exposed insulation, damp and mould risk, blocked ventilation and exposed electrical cabling. Remediation costs ranged from £250 to £18,000 per property, with extreme cases reaching £250,000.

The NAO put the failures down to weak government oversight and a fragmented system, with roles split across DESNZ, Ofgem and others, and a consumer protection system that did not flag the problems to the department until late 2024. Installers could be certified by more than one body, which let some of them work around the audit process. The report also estimated suspected fraud affecting 5,600 to 16,500 homes, worth between £56 million and £165 million. By September 2025, only about 8% of the EWI homes and 10% of the IWI homes identified for repair had been fully fixed. The responsible minister described the findings as unacceptable systemic failings. Thirty-eight installers were suspended.

Getting a GBIS installation checked and repaired

Ofgem wrote to around 65,000 households whose insulation might be affected. A home that had external wall insulation fitted under ECO4 or GBIS can get a free audit through TrustMark’s Find & Fix service, which arranges any repairs needed at no cost to the homeowner. Ofgem’s letters carry a Unique Measure Reference Number (UMRN) that identifies the specific installation for the audit. Some affected homeowners have been unable to remortgage or sell while an insulation problem is unresolved.

What GBIS insulation means for a heat pump

GBIS funded insulation on its own, not as part of a coordinated heating plan. A heat pump is sized to a home’s heat loss, so better insulation lowers the heat demand and can reduce the capacity, and the running cost, of the system a home needs. Insulating first is the fabric-first principle that heat pump sizing relies on.

The quality failures cut the other way. Damp, mould and blocked or insufficient ventilation are the problems a heat pump installer would need resolved before designing a system, because they affect both the fabric performance the sizing assumes and the ventilation the home depends on. A poorly installed GBIS measure could add remediation work to a heat pump project rather than remove it. Anyone moving from GBIS insulation towards a heat pump should confirm the insulation is sound first, and if the measure was external wall insulation, the free audit is there to use if there is any doubt.

GBIS and ECO4

GBIS and ECO4 are separate strands of the Energy Company Obligation. GBIS, the ECO4A strand, funded single insulation measures and had the wider eligibility, with the general group qualifying on EPC and council tax band alone. ECO4 is a whole-house retrofit scheme for low-income households, and it can fund heat pumps, solar panels and boiler upgrades as well as insulation. ECO4 also requires a minimum improvement in a home’s SAP rating, which GBIS did not. Both schemes were caught by the same NAO quality findings. GBIS closed on 31 March 2026; ECO4 runs until 31 December 2026.

What remains now GBIS has closed

The Budget of 26 November 2025 confirmed the end of GBIS. The central referral service had already shut, with some suppliers processing existing applications for a period afterwards. Other support continues, but under different schemes. ECO4 remains open until 31 December 2026. The Home Upgrade Grant has closed and GOV.UK now directs households to the Warm Homes: Local Grant, an England-only programme delivered through participating local authorities. The Boiler Upgrade Scheme continues to support eligible heating installations in England and Wales. The wider Warm Homes Plan was published in January 2026, so it should no longer be described as an unconfirmed future scheme.