The Energy Company Obligation phase 4 (ECO4) is the UK's principal supplier-funded retrofit programme, running from April 2022 to March 2026. It targets low-income, vulnerable and fuel-poor households, delivering insulation, heating and renewable measures via accredited installers. This page collates ECO4 grant statistics published by Ofgem, including scheme spend, measure breakdowns, LA Flex uptake and average grant values. Where final FY25/26 figures are not yet released, we mark estimates clearly.
Total ECO4 scheme spend
ECO4 was set with a four-year supplier obligation funding pool of approximately £4.0 billion. According to Ofgem reporting through 2024-2025, supplier delivery has tracked broadly toward the obligation target but with notable annual variation:
| Financial year | Approximate ECO4 spend / measure value | Notes |
|---|---|---|
| FY22/23 | ~£0.7-0.8 bn | Ramp-up phase |
| FY23/24 | ~£1.0-1.1 bn | Steady delivery |
| FY24/25 | ~£1.0-1.2 bn (est.) | Estimated for FY24/25 from Ofgem interim data |
| FY25/26 | ~£0.9-1.0 bn (est.) | Estimated for FY25/26; scheme closes 31 March 2026 |
Source: Ofgem ECO4 quarterly reports. Scheme spend is reported as obligated suppliers' delivered measure value.
Measure breakdown
ECO4 prioritises whole-house retrofit, requiring properties to reach a minimum EPC band uplift. According to Ofgem ECO4 measure-by-measure data through 2024-2025, the approximate share of installed measures by count is:
| Measure category | Approximate share of ECO4 measures installed |
|---|---|
| Loft insulation (top-up and full) | ~25-30% |
| Cavity wall insulation | ~10-12% |
| Solid wall insulation (EWI/IWI) | ~12-15% |
| Underfloor insulation | ~3-5% |
| Heating controls / TRVs | ~10-12% |
| Boiler / first-time central heating | ~12-15% |
| Air source heat pumps | ~5-7% |
| Solar PV (linked to ECO4) | ~3-5% |
| Other (windows, doors, room-in-roof) | ~5-8% |
Solid wall insulation has grown materially under ECO4 versus prior phases, partly because it delivers larger EPC band uplifts and helps suppliers hit the scheme's whole-house targets.
LA Flex uptake
LA Flex (Local Authority Flexible Eligibility) allows councils to broaden ECO4 eligibility to households not on means-tested benefits but who meet local fuel poverty criteria. Uptake has grown substantially under ECO4:
- Approximate share of ECO4 households reached via LA Flex routes: ~30-40% by FY24/25 (up from approximately 15-20% in earlier ECO phases)
- Number of UK local authorities operating ECO4 LA Flex statements of intent: estimated at ~250-280 as of 2025
- Most active LA Flex local authorities are typically in areas with high fuel poverty rates and dense terraced housing stock
Source: Ofgem ECO4 supplier returns, individual LA Flex SoI publications.
Average grant value per household
Average ECO4 measure value per household varies sharply by measure depth. Whole-house treatments combining wall insulation plus heating upgrades carry the highest values:
| Measure profile | Approximate measure value (GBP) |
|---|---|
| Loft top-up only | £500-£1,200 |
| Cavity wall insulation | £700-£1,800 |
| External wall insulation (full house) | £9,000-£15,000 |
| Internal wall insulation (full house) | £5,000-£9,000 |
| First-time central heating system | £3,500-£5,500 |
| ASHP installation (under ECO4) | £9,000-£14,000 |
| Whole-house package (typical) | £12,000-£25,000+ |
Figures are typical mid-range estimates from accredited ECO4 installer cost data.
Qualifying household profile
ECO4 eligibility centres on specific means-tested benefits or LA Flex declarations. Typical qualifying household profiles include:
- Recipients of Pension Credit, Universal Credit, Income-based JSA, Income-related ESA, Income Support, Working Tax Credit or Child Tax Credit (subject to thresholds)
- Households declared eligible by a local authority under LA Flex (typical thresholds: household income under approximately £31,000, or specific health/vulnerability conditions)
- EPC bands D, E, F or G eligible; private tenure properties with EPC F/G face additional minimum standards under MEES
- Properties off the gas grid see priority routing for first-time heating systems
- Owner-occupiers, private tenants (with landlord consent), and certain housing association properties are eligible
Successor scheme: ECO5 and beyond
ECO4 closes on 31 March 2026 and government has consulted on the design of a successor obligation often referred to informally as ECO5. Approximate parameters under consultation as of 2025:
- Successor scheme term: typically 4 years (e.g. April 2026 - March 2030)
- Indicative budget envelope: approximately £3-5 billion over the four-year period
- Continued whole-house focus expected, with tighter ventilation and moisture risk requirements
- Higher minimum energy efficiency targets; possible PAS 2035:2023 mandatory uplift
- Continued LA Flex eligibility routes, possibly with national consistency improvements
- Potential introduction of low-carbon heat-specific obligation pathways alongside CHMM
Final scheme design is subject to consultation outcomes and ministerial decisions; transition arrangements between ECO4 and the successor obligation will be critical for installer pipeline continuity.
ECO4 carbon and energy savings
ECO4 obligations are denominated in lifetime carbon and energy savings (the cost score), which suppliers must deliver. Approximate cumulative scheme outcomes through end-2024:
- Cumulative ECO4 lifetime carbon savings (CO2): approximately ~14-18 MtCO2
- Cumulative ECO4 lifetime energy savings: approximately ~50-65 TWh
- Average lifetime savings per measure: typically 2-15 tCO2 depending on measure depth
- Average lifetime savings per whole-house package: typically 20-50 tCO2
Carbon and energy savings are scored using SAP-based methodologies prescribed by Ofgem; the actual realised savings depend on installation quality, occupancy and use patterns.
ECO4 contractor and installer base
ECO4 measures must be installed by TrustMark-registered installers who hold the relevant scheme accreditation (PAS 2030/2035 for retrofit measures). Approximate ECO4 installer market:
- TrustMark-registered businesses delivering ECO4 measures: approximately ~2,500-3,200
- Insulation-only installers: approximately ~1,200-1,600
- Heating system installers operating under ECO4: approximately ~700-900
- Multi-measure (whole-house) installers: approximately ~600-900
- Average annual measures per installer: highly variable, typically 40-200 measures per business
Installer churn under ECO4 has been notable, partly driven by PAS 2035 compliance costs and the operational complexity of whole-house retrofit. Ofgem and TrustMark have published guidance on common audit findings to help installers maintain accreditation.
ECO4 supplier obligation distribution
ECO4 obligations are placed on the ten largest licensed energy suppliers, with each supplier's share of the obligation set in proportion to their domestic customer count. Approximate share by major obligated supplier (typical recent reporting period):
| Obligated supplier | Approximate share of ECO4 obligation |
|---|---|
| Octopus Energy (incl. Bulb portfolio) | ~24-26% |
| British Gas / Centrica | ~18-20% |
| OVO Energy (incl. SSE retail) | ~13-15% |
| EDF Energy | ~10-12% |
| E.ON Next | ~10-12% |
| ScottishPower | ~7-9% |
| Other obligated suppliers | ~6-10% |
Shares fluctuate with customer migration; figures are approximate annual averages.
ECO4 measure delivery channels
ECO4 measures are delivered through three principal channels:
- Direct supplier-managed delivery: obligated suppliers run their own retrofit programmes via in-house teams or framework contractors. Approximate share: ~35-40% of measures.
- Aggregator-led delivery: third-party aggregators source eligible households, manage installer networks and sell measure packages to obligated suppliers. Approximate share: ~45-55% of measures.
- Local Authority partnership: councils and housing associations partner with suppliers and installers to deliver measures across geographic catchments. Approximate share: ~10-15% of measures.
The aggregator channel has been the largest delivery route under ECO4, although Local Authority partnerships have grown in importance as LA Flex routes have expanded.
ECO4 EPC band uplift requirements
ECO4 mandates a minimum EPC band uplift per treated property, with whole-house outcomes prioritised. Approximate share of ECO4 measures by EPC starting band:
| EPC starting band | Approximate share of ECO4 properties treated | Typical target uplift |
|---|---|---|
| D | ~35-40% | up to band C |
| E | ~35-40% | up to band D minimum |
| F | ~15-18% | up to band D minimum |
| G | ~5-8% | up to band D minimum |
The whole-house focus has materially increased the average measure depth per property versus prior ECO phases, contributing to higher per-property delivery costs.
Great British Insulation Scheme (GBIS) overlap
The Great British Insulation Scheme (GBIS), launched in 2023 alongside ECO4, broadens insulation eligibility to lower-EPC owner-occupiers and private tenants without strict means-testing. Although a separate scheme, GBIS is delivered by the same obligated suppliers and installer base. Approximate GBIS metrics through end-2025:
- GBIS scheme budget: approximately £1.0 billion over 2023-2026
- Cumulative GBIS measures installed by end 2024: approximately ~120,000-140,000
- Estimated cumulative GBIS measures by end 2025: approximately ~200,000-230,000
- Average GBIS measure value: approximately £1,100-£2,000
- Most common GBIS measures: loft insulation, cavity wall insulation
Data caveats
The following caveats apply to ECO4 data:
- Ofgem reports ECO4 progress against the supplier obligation; some measures install in one financial year but are reconciled in another.
- FY24/25 and FY25/26 figures are estimated from Ofgem interim data; the final annual report typically lags scheme close by 6-12 months.
- Measure counts can include partial measures (top-ups) which may not deliver a full EPC band uplift on their own.
- Average measure values are mid-range estimates and individual project costs vary by property type and region.
- LA Flex uptake numbers are aggregated from individual local authority Statements of Intent and may slightly under-count councils with lapsed SoIs.
- GBIS data is reported separately from ECO4 although delivered by the same supplier base; some properties qualify for both schemes.
ECO4 has materially shifted UK supplier-funded retrofit toward whole-house solid wall and low-carbon heating measures, with LA Flex pathways now accounting for roughly a third of household uptake. The parallel GBIS scheme has expanded insulation reach beyond strict means-tested eligibility. As ECO4 closes in March 2026 and the successor obligation begins, ECO4 data is the baseline against which any future scheme will be measured. Use this data freely with attribution to ecosavinghub.co.uk. Last updated: 2026-05-08.
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