The short answer
ECO4 is the fourth phase of the Energy Company Obligation, a UK scheme that requires larger energy suppliers to fund energy-efficiency improvements — including external (solid) wall insulation — in low-income and vulnerable households. It is overseen by Ofgem and delivered by suppliers through TrustMark-registered installers working to PAS 2030/2035. ECO4 takes a fabric-first, whole-house approach: rather than funding one measure in isolation, it aims to lift a property up the EPC bands, so solid wall insulation is usually delivered as part of a package. Eligibility is based on receiving certain benefits or, via a local authority route, being on a low income or vulnerable. Check current rules on gov.uk or Ofgem, as the scheme is periodically reviewed.
ECO4 is the main route through which solid wall insulation gets funded for eligible UK households. Here is how it works and who it reaches.
ECO4 at a glance
- Full nameEnergy Company Obligation (phase 4)
- Overseen byOfgem
- Delivered byObligated energy suppliers
- ApproachFabric-first, whole-house
- StandardsPAS 2030/2035, TrustMark
How ECO4 works
ECO is an obligation, not a grant pot you apply to directly. The government requires larger energy suppliers to deliver a set amount of energy savings by funding improvements in qualifying homes, and Ofgem regulates and audits that delivery. For wall insulation, this means a supplier (or a contractor working on their behalf) funds the installation of solid wall (external or internal) insulation where it is appropriate, carried out by a TrustMark-registered installer to the PAS 2030/2035 retrofit standards, following a retrofit assessment of the property.
| Element | ECO4 detail | Note |
|---|---|---|
| Funding source | Energy suppliers | obligation, not a direct grant |
| Regulator | Ofgem | sets and audits rules |
| Approach | Whole-house, fabric-first | aims to raise EPC band |
| Wall measure | Solid wall insulation | external or internal |
Indicative ECO4 structure, 2026. Confirm current rules on gov.uk or Ofgem.
Fabric-first and the whole-house approach
A defining feature of ECO4 is that it is fabric-first and whole-house. Rather than fitting a single measure, the scheme looks at the property as a whole and aims to improve its overall EPC rating, often by combining measures such as insulation, heating improvements and controls. For a solid-walled home, external wall insulation can be a major part of that package because the walls are usually the largest heat-loss surface. This approach means EWI under ECO4 is typically part of a planned retrofit, not a standalone job.
Who qualifies for ECO4
ECO4 targets low-income and vulnerable households. The main route is receiving certain means-tested benefits — for example Universal Credit, Pension Credit, Income Support and several others. There is also a flexible eligibility route, sometimes called LA Flex, where a local authority can refer households that are on a low income, vulnerable to the cold, or living in poor-quality housing, even if they are not on a listed benefit. Priority is generally given to the least efficient properties (lower EPC bands) where the improvement potential is greatest.
Because the precise benefit list and eligibility criteria are set by the scheme rules and updated over time, the reliable way to check is through the official gov.uk eligibility pages, Ofgem, or your energy supplier. A local authority's website will set out its flexible eligibility criteria if it operates that route.
How to access ECO4 funding
The factual process is straightforward and involves no sales steps. You check eligibility through gov.uk, your energy supplier, or a local authority flexible-eligibility scheme. If you appear to qualify, an approved installer carries out a retrofit assessment of the home to confirm which measures are appropriate. Where solid wall insulation is recommended, it is then installed to PAS 2030/2035 by a TrustMark-registered installer, funded under the scheme. You should receive documentation and a guarantee for the installed measure.
Two cautions apply. First, only deal with official channels and registered installers — not doorstep callers promising free insulation. Second, the scheme is time-limited and periodically reviewed, so confirm the current rules and whether the scheme is open before relying on it. For households that do not qualify, privately paid EWI still benefits from 0% VAT on installed energy-saving materials in Great Britain under the relief running to 31 March 2027.
How ECO4 fits alongside other schemes
ECO4 does not operate in isolation, and understanding where it sits helps you find the right route. It runs alongside the Great British Insulation Scheme (GBIS), which is also delivered by obligated energy suppliers but opens a route based on the property's EPC and council tax band rather than benefits — useful for households on ordinary incomes who would not pass ECO4's means test. The two schemes can overlap, and a supplier or installer delivering both will usually point you to whichever you qualify for. ECO4 tends to fund the deepest, whole-house retrofits for the least efficient homes, while GBIS more often funds a single measure such as wall insulation.
The devolved nations also have their own advice and funding routes layered over the UK-wide supplier obligation. In Scotland, Home Energy Scotland advises on funded support including Warmer Homes Scotland; in Wales, the Nest / Warm Homes programme plays a comparable role; and local authorities across the UK run their own area-based schemes that may channel ECO funding street by street. Because these programmes change and are periodically refreshed, the dependable approach is to start with the official gov.uk and Ofgem pages, or your nation's energy advice service, and let them direct you to the scheme that fits your home and circumstances. ECO4 is a major part of that landscape for solid wall insulation, but it is rarely the only option worth checking.
It also helps to keep the timescale in mind. ECO operates in defined phases — ECO4 being the current one — each with its own start and end dates, budget and rules, so a scheme that is open and funding solid wall insulation now may be revised or replaced in a future phase. The practical implication is to act on the current guidance rather than older articles, confirm directly that the scheme is still running when you check, and not assume that criteria you read about a year or two ago still apply. If you qualify, it is generally worth proceeding while funding is available rather than waiting, because budgets are finite and demand for the deepest measures such as external wall insulation is high.
Frequently asked questions
What is the ECO4 scheme for wall insulation?
ECO4 is the fourth phase of the Energy Company Obligation, requiring larger energy suppliers to fund energy-efficiency improvements — including solid wall insulation — in low-income and vulnerable UK homes, regulated by Ofgem and delivered to PAS 2030/2035 standards.
Does ECO4 pay for external wall insulation?
Yes, where appropriate. ECO4 can fund solid wall insulation, which includes external wall insulation, usually as part of a whole-house, fabric-first package aimed at lifting the property's EPC rating, rather than as a standalone measure.
How do I know if I qualify for ECO4?
Eligibility is based on receiving certain means-tested benefits or being supported through a local authority's flexible eligibility route. Check the current criteria via gov.uk, Ofgem or your energy supplier, as the rules are periodically updated.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation.