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ECO4 Energy Company Obligation

Supplier-funded energy efficiency and heating scheme for eligible low-income, fuel-poor and vulnerable households in Great Britain.

Scheme status, eligibility rules and live programme details were checked on 22 July 2026. Historical delivery and funding figures retain the date stated with them.

ECO4 (Energy Company Obligation 4) is the fourth phase of the Energy Company Obligation, a Great Britain government energy efficiency scheme aimed at fuel poverty and carbon reduction. It places a Home Heating Cost Reduction Obligation (HHCRO) on medium and large energy suppliers, requiring them to fund energy efficiency and heating measures in low-income, fuel-poor and vulnerable households. The Department for Energy Security and Net Zero (DESNZ) sets the policy and Ofgem, the energy regulator, administers the scheme.

ECO4 runs under the Electricity and Gas (Energy Company Obligation) Order 2022 (statutory instrument 2022/875), which came into force in July 2022, and it applies to measures installed from 1 April 2022. It was originally due to end on 31 March 2026 but has been extended by nine months to 31 December 2026. At the November 2025 budget the government announced that the Energy Company Obligation would close, with no ECO5 or successor supplier obligation planned. The government published the Warm Homes Plan in January 2026. Its grant programmes use a different delivery model rather than continuing ECO as another supplier obligation.

The supplier obligation and whole-house approach

Ofgem calculates each obligated supplier’s target from its share of the domestic gas and electricity market. Suppliers meet the target by funding or part-funding measures in homes that qualify. Ofgem processes notifications of completed work, audits suppliers, runs counter-fraud checks and reports on progress. TrustMark, the government-endorsed quality scheme for domestic retrofits, handles the quality assurance side. The scheme’s stated objectives are to reduce fuel poverty, contribute to carbon reduction targets, lower the cost of meeting the renewable energy target and encourage innovation in the industry.

ECO4 uses a whole-house retrofit approach set out in PAS 2035:2019, the domestic retrofit standard, rather than the single-measure focus of earlier phases. A property is assessed as a whole and several measures are installed together. Each treated property has to improve its Standard Assessment Procedure (SAP) rating by a set minimum. A home starting at SAP band F or G must reach at least band D. A home starting at band D or E must reach at least band C.

Who qualifies for ECO4

Eligibility depends on benefits receipt, the property’s condition and the housing tenure. A household qualifies through benefits if the occupier receives at least one of the following:

  • Child Benefit
  • Pension Guarantee Credit
  • Income-related Employment and Support Allowance (ESA)
  • Income-based Jobseeker’s Allowance (JSA)
  • Income Support
  • Universal Credit
  • Housing Benefit
  • Pension Credit Savings Credit

The property has to need energy efficiency upgrades, which a retrofit assessment confirms. The occupier must own the home or have the landlord’s permission, including where the property belongs to a social housing provider or management company.

ECO4 Flex is a second route into the scheme. Local authorities, the Scottish government and the Welsh government can refer low-income or vulnerable households who do not receive the qualifying benefits but meet alternative criteria: a combined gross annual household income under £31,000, or a household member with a severe or long-term health condition made worse by living in a cold home, such as a cardiovascular condition, respiratory disease, limited mobility or immunosuppression. Energy suppliers can also refer households under ECO4 Flex where the occupier is in persistent fuel debt or is on a pre-payment meter and has repeatedly been unable to stay connected because of financial hardship.

Qualifying does not guarantee an installation. Ofgem is explicit that eligibility for ECO does not mean a supplier or installer will decide to fit measures in a given home. The decision rests with the supplier.

Measures ECO4 funds

ECO4 covers a range of measures listed in the ECO4 measures table. The list is non-exhaustive, and other measures may qualify subject to Ofgem review case by case. The main categories are:

  • Insulation: cavity wall, solid wall (external and internal), loft, underfloor and room-in-roof insulation.
  • Heating: heat pumps, boiler upgrades, electric storage heaters, first-time central heating and connections to district heating networks.
  • Solar PV panels, which appear in the scheme’s scoring matrix as a recognised measure type.

Window glazing is eligible where it replaces single glazing with double glazing, or replaces older double glazing that no longer meets current building regulations. It covers factory-made sealed window units only, not secondary glazing. New doors and window replacements that do not meet the rules are outside the scheme.

Homes that already meet the relevant efficiency rating do not qualify. On this basis owner-occupied private homes generally need an Energy Performance Certificate (EPC) rating of D, E, F or G, while private rented and social housing usually need E, F or G. ECO4 generally cannot be combined with other funding sources. Battery storage is generally not funded and usually has to be paid for separately, even where solar PV is covered.

For off-gas premises the ECO4 Order sets a hierarchy of heating measures, with a minimum level of insulation required before certain heating measures can be installed. A household cannot simply choose a preferred upgrade. The retrofit assessor identifies which measures would benefit the property, and suitability for a given measure such as solar PV depends on the property, including factors like roof condition.

How measures are scored

Each measure or project receives a score based on the annual bill saving it achieves in an eligible home, and that score sets how much it counts towards the supplier’s Home Heating Cost Reduction Obligation. There are two scoring pathways. Full project scores apply to whole-house retrofits that meet the minimum SAP improvement. Partial project scores apply to individual measures or projects that fall short of the full improvement. The methodology also allows innovation measure uplifts of 25% or 45% above the standard score, increases for building fabric repairs and penalties for late completion.

Suppliers can meet up to 10% of their obligation through Innovation Measures (IMs), and no more than 5% through any single innovation product. Because scores drive how a supplier hits its target, the packages a supplier chooses to fund tend to follow where the scores are highest, which is part of why eligibility alone does not secure an installation.

Installer registration and retrofit standards

Every ECO4 installer must be a TrustMark-registered business, with the sole exception of installers of district heating connections that are not linked to a shared ground loop. Ofgem uses data shared by TrustMark to check compliance against the scheme rules.

Projects follow the domestic retrofit process in PAS 2035:2019, and measures are installed to PAS 2030:2019. A 2025 update to the ECO4 Order moves these references to the 2023 versions of both standards. Each project starts with a pre-retrofit assessment that establishes the property’s starting SAP rating and identifies the measures that would benefit it.

The 2025 insulation quality failures

Ofgem reported 243,900 homes upgraded under ECO4 to the end of March 2025, and the government expects ECO4 and the Great British Insulation Scheme together to deliver around £280 million in annual bill savings. Alongside that delivery, serious quality problems surfaced.

TrustMark alerted DESNZ to suspected fraud in April 2024, then to high rates of non-compliant external wall insulation in October 2024 and internal wall insulation in November 2024. In January 2025 DESNZ suspended 39 businesses from installing new solid wall insulation. The National Audit Office (NAO) published its report on the schemes in October 2025.

The NAO found that 98% of homes fitted with external wall insulation (EWI) under ECO4 and the Great British Insulation Scheme had major issues needing remediation, along with 29% of homes fitted with internal wall insulation (IWI). Between 22,000 and 23,000 homes need EWI remediation and between 9,000 and 13,000 need IWI remediation. More than 1,000 homeowners were living with faults posing an immediate health and safety risk, including exposed live electrical cabling and blocked boiler ventilation. By mid-September 2025, only about 8% of the EWI homes and 10% of the IWI homes identified for remediation had been fully repaired. Ofgem estimated that businesses had falsified claims for installations in up to 16,500 homes, potentially claiming between £56 million and £165 million from energy suppliers.

The NAO traced the failures to an under-skilled workforce, businesses cutting corners, uncertainty over which standards applied to which jobs, weak oversight and a fragmented system with responsibilities split across DESNZ, Ofgem and other bodies. DESNZ’s most senior official told parliament there had been failures at every level of the system, and the energy minister called the failings unacceptable and systemic. The government committed to full remediation at no cost to affected homeowners, along with tighter controls and clearer accountability in future schemes.

Closure and the Warm Homes Plan

The November 2025 budget announced the closure of the Energy Company Obligation as part of a plan to cut household bills, quoted at an average of £150 a year, funded partly by ending the levy on bills that supports ECO. ECO4 itself was extended to 31 December 2026 so existing projects can complete. The Great British Insulation Scheme, a single-measure insulation scheme that ran alongside ECO4, ended on 31 March 2026 as planned and was not extended.

The government has said there will be no ECO5 or further supplier obligation. Some installer websites describe an “ECO5” scheme launching after ECO4, but the confirmed government position is that the ECO framework ends and grant funding takes over. The Warm Homes Plan was published on 21 January 2026. One of its live programmes is the Warm Homes: Local Grant, delivered by participating English local authorities from April 2025 to March 2028. It supports energy-efficiency and low-carbon-heating work in low-income, privately owned homes. The overall plan carries a £15 billion commitment, including £4.4 billion for low-income-home grants; £500 million is allocated to the Local Grant.

Applying before the December 2026 deadline

The scheme is open until 31 December 2026, and applications take time to move from assessment to installation. Some funders and installers have paused new work following the announced closure, so availability may be limited even while the scheme technically remains open.

Cold callers and leaflet drops from companies with no verifiable online presence are a known risk. Legitimate ECO4 installers are TrustMark-registered and can be checked against the TrustMark register. Given the scale of the faults the NAO identified, a household weighing up an offer has good reason to confirm the installer’s registration and the standard the work will be carried out to before agreeing to anything.

Applies to

Solar, Battery, Heat

Last reviewed

22 Jul 2026