With UK energy bills having risen significantly since 2021, improving your home's insulation is one of the smartest financial decisions you can make. A well-insulated home retains heat more effectively in winter and stays cooler in summer, reducing reliance on heating and cooling systems. The Energy Saving Trust estimates that a typical uninsulated UK home loses around 25% of its heat through the roof and 35% through walls.
The UK government continues to offer substantial grants through ECO4 and the Great British Insulation Scheme to help households reduce their carbon footprint and energy bills. In 2026, eligible households can receive insulation entirely free of charge.
| Insulation Type | Annual Saving | Install Cost | Payback Period | EPC Improvement |
|---|---|---|---|---|
| Loft (0 to 270mm) | £150-£300 | £300-£600 | 1-3 years | 1-2 bands |
| Cavity Wall | £250-£400 | £800-£1,800 | 2-5 years | 1-2 bands |
| Solid Wall (External) | £400-£700 | £8,000-£25,000 | 15-40 years | 2-3 bands |
| Solid Wall (Internal) | £350-£600 | £4,000-£12,000 | 8-25 years | 2-3 bands |
| Underfloor (Suspended) | £65-£150 | £400-£2,000 | 5-15 years | 0-1 bands |
| Draught Proofing | £25-£65 | £100-£350 | 2-6 years | 0-1 bands |
The Energy Company Obligation 4 (ECO4) scheme obligates large UK energy suppliers to fund insulation and heating improvements for vulnerable and low-income households. You may qualify if you receive: Universal Credit, Pension Credit, Child Tax Credit, Working Tax Credit, Housing Benefit, Income Support, or income-based JSA or ESA.
Under ECO4, qualifying households can receive loft insulation, cavity wall insulation, solid wall insulation, and even new boilers entirely free of charge. Contact your energy supplier's ECO4 team or use the government's Simple Energy Advice service to check eligibility.
Running alongside ECO4, the Great British Insulation Scheme (GBIS) targets homes in council tax bands A-D with an EPC rating of D-G. Unlike ECO4, you do not need to be on benefits to qualify - households with higher incomes may still receive subsidised insulation. The scheme focuses on single measures (typically loft or cavity wall insulation) and aims to improve approximately 300,000 UK homes.
An Energy Performance Certificate (EPC) rates your home on a scale from A (most efficient) to G (least efficient). EPCs affect you in several important ways:
Poorly installed insulation can cause damp, condensation, and structural problems. Always verify your installer holds:
Always request a written quote, a pre-installation survey, and a guarantee certificate before any work begins. Get at least 3 quotes for work costing over £1,000.
Installing 270mm of loft insulation in a home with no existing insulation can save £150-£300 per year on energy bills. For a typical semi-detached house, savings average around £215 per year. Installation costs £300-£600, giving a payback period of 1-3 years - one of the best return-on-investment home improvements available. If you already have 100mm of loft insulation, topping up to 270mm can still save £50-£100 annually.
ECO4 (Energy Company Obligation 4) obligates large energy suppliers to fund insulation and heating improvements for low-income and vulnerable households. You may qualify if you receive means-tested benefits (Universal Credit, Pension Credit, Housing Benefit, Income Support, Tax Credits) or have a low household income, or live in a property with an EPC rating of D-G. Contact your energy supplier directly or use the government's Simple Energy Advice service at simpleenergyadvice.org.uk to check eligibility and apply.
Yes, for most properties with unfilled cavity walls, cavity wall insulation is excellent value. It costs £800-£1,800 and can save £250-£400 per year on energy bills, giving a payback period of 2-5 years. Properties built between 1930-1990 typically have suitable cavities. A CIGA-certified installer will survey your walls to confirm suitability - cavity walls are not appropriate for all properties, particularly those in high-exposure locations or with pre-existing moisture issues.
The Great British Insulation Scheme (GBIS) provides funding for single insulation measures to households in council tax bands A-D with an EPC rating of D-G. Unlike ECO4, you do not need to be on benefits - it targets the broader population of households in less energy-efficient homes. Qualifying homeowners can receive loft or cavity wall insulation either free or heavily subsidised. The scheme is delivered through energy suppliers and local authorities.
External solid wall insulation costs £8,000-£25,000 for a typical house (it requires rendering or cladding the entire exterior and is usually done street-by-street through area-based schemes). Internal wall insulation (dry lining) costs £4,000-£12,000 but reduces room size slightly. Despite the high cost, solid wall insulation can save £400-£700 per year. For pre-1920 solid-wall properties, it is the primary way to significantly improve energy efficiency. ECO4 may cover all costs for eligible households.
Insulation is one of the most effective ways to improve your EPC rating. Adding loft insulation typically improves your rating by one band (e.g., E to D). Cavity wall insulation may improve it by one to two bands. Solid wall insulation can improve ratings by two to three bands. A higher EPC rating can unlock better mortgage rates through green mortgage products, is required by law for private landlords (minimum EPC E), and adds demonstrable value at the point of sale.
Check your installer holds TrustMark registration (government-endorsed quality scheme), CIGA certification for cavity wall work (providing a 25-year guarantee), PAS 2030 certification for any ECO scheme-funded work, and NIA or INCA membership for solid wall insulation. For ECO4 and GBIS-funded work, PAS 2030 and PAS 2035 certification is a legal requirement. Always request a pre-installation survey, written guarantee, and obtain at least 3 quotes for larger jobs.