Free or subsidised insulation is one of the most effective ways to cut heating bills without taking on expensive works yourself. In 2026, two main government schemes are running — ECO4 and the Great British Insulation Scheme (GBIS) — alongside a patchwork of local authority grants. This guide explains what each scheme covers, who qualifies, and how much you can realistically expect to receive.
ECO4: The Flagship Fully-Funded Scheme
ECO4 (Energy Company Obligation 4) runs until March 2026 and requires the six largest energy suppliers to fund home energy improvements for lower-income and vulnerable households. If you qualify, works are fully funded — you pay nothing.
What ECO4 covers:
- Loft insulation (top-up or first-time)
- Cavity wall insulation
- Solid wall insulation (internal or external)
- Underfloor insulation
- Flat roof and room-in-roof insulation
Eligibility is means-tested. You typically qualify if you receive one of the following:
- Universal Credit (with an income cap of around £31,000 net earnings)
- Pension Credit
- Child Tax Credit or Working Tax Credit
- Income Support or income-related Employment and Support Allowance
- Housing Benefit
Your home also needs to have an Energy Performance Certificate (EPC) rating of D, E, F, or G. Properties rated A, B, or C are generally excluded unless you live in a rural or off-gas-grid area.
[!tip] EPC Requirement If you don’t have a current EPC, your installer can arrange one as part of the assessment — it’s free under ECO4.
Typical ECO4 insulation values:
| Measure | Average installed cost | Funded by ECO4 |
|---|---|---|
| Loft insulation (270mm, semi-detached) | £300–£600 | 100% |
| Cavity wall insulation | £500–£1,500 | 100% |
| Solid wall insulation (external) | £8,000–£22,000 | 100% |
| Underfloor insulation (suspended) | £800–£2,000 | 100% |
Great British Insulation Scheme (GBIS)
GBIS is broader than ECO4 — it targets the least energy-efficient homes rather than only low-income households, meaning many owner-occupiers and private tenants who don’t qualify for ECO4 can still access help.
How GBIS works: Energy suppliers are required to fund a set number of insulation measures per year. They typically work through approved installers or local council referral schemes.
Eligibility — two tracks:
- Low-income track: Households receiving means-tested benefits (similar to ECO4), EPC D–G. Likely to receive full funding.
- General track: Any household in an EPC D–G property, regardless of income, in council tax bands A–D in England (A–E in Scotland and Wales). Partial funding is typical — you may contribute £500–£3,000 depending on the measure and your circumstances.
GBIS focuses on single-measure installs. Unlike ECO4, which often funds a package of measures, GBIS is designed to deliver one insulation improvement per home.
Typical GBIS grant levels (2026):
| Measure | Estimated grant | Typical homeowner contribution |
|---|---|---|
| Loft insulation top-up | Full cost (£300–£600) | £0–£100 |
| Cavity wall insulation | £400–£1,200 | £0–£500 |
| Solid wall insulation | £5,000–£12,000 | £2,000–£8,000+ |
| Flat roof insulation | £400–£1,000 | £0–£300 |
Note: Solid wall insulation rarely receives 100% GBIS funding on the general track. If your home has solid walls (pre-1920 brick or stone), ECO4 eligibility is worth checking first.
Local Authority Grants and Blended Funding
Many councils operate their own top-up grants or act as intermediaries for Warm Homes: Local Grant funding. These can be stacked with GBIS or ECO4 contributions. Examples from 2025–2026:
- Some London boroughs offer an additional £2,000–£5,000 toward solid wall insulation for fuel-poor households
- Several rural councils top up GBIS for off-gas homes with air source heat pump packages
- Warm Homes: Local Grant (successor to the Home Upgrade Grant) offers up to £15,000 for off-gas properties with EPC D–G in England
Check your local council’s website directly or use the Simple Energy Advice (SEA) service at simpleenergyadvice.org.uk.
How to Apply
- Check your EPC rating — find it at the GOV.UK EPC register (England, Scotland, or Wales versions differ).
- Use the eligibility checker on simpleenergyadvice.org.uk or call the Energy Saving Advice Service on 0800 444 202.
- Contact an approved installer — look for Trustmark-registered and PAS 2030:2019 certified contractors. ECO4 and GBIS installers will handle the supplier referral on your behalf.
- Get at least two quotes for any co-funded works.
[!warning] Avoid Cold Callers Legitimate ECO4 and GBIS works are never initiated by unsolicited door-knocking. If someone appears offering “free insulation” without prior contact, verify them against the Trustmark register before allowing access.
What the Savings Look Like
Energy bill savings vary significantly by property type and existing insulation state. Indicative annual savings based on typical UK semi-detached homes (2026 energy prices):
| Measure | Estimated annual saving |
|---|---|
| Loft insulation (none → 270mm) | £180–£300 |
| Cavity wall insulation | £150–£350 |
| Solid wall insulation (external) | £300–£600 |
| Draught-proofing (often bundled) | £50–£100 |
Payback on fully-funded measures is immediate — you’re saving from day one. For co-funded solid wall insulation, a homeowner contribution of £5,000 with £400/year savings implies a 12–15 year payback before energy price changes.
What ECO4 and GBIS Do Not Cover
- Properties with an EPC of C or above (unless rural/off-gas exceptions apply)
- New-build homes
- Holiday lets or empty homes
- Listed buildings (restrictions on external solid wall insulation apply — internal lining may still qualify)
- Insulation-only improvements in homes that already have reasonable insulation (GBIS prioritises homes with EPC D or worse)
Building Regulations
Insulation installed under ECO4 or GBIS must comply with Part L of the Building Regulations (Conservation of Fuel and Power). Cavity wall insulation must meet BS EN ISO 9229 standards and be certified by the British Board of Agrément (BBA) or equivalent. Solid wall insulation must achieve a U-value of 0.30 W/m²K or better for external, 0.29 W/m²K for internal. Your installer is responsible for notifying Building Control if required, though most cavity wall and loft work is exempt from formal notification under the Competent Persons Scheme.
