Insulation is the highest-impact energy upgrade most UK homes can make — and it's often partly or fully funded for households on lower incomes. The ECO4 and Great British Insulation Scheme (GBIS) programmes channel hundreds of millions into loft, cavity wall and solid wall measures every year. This guide explains who qualifies and what to expect.
ECO4 (Energy Company Obligation, phase 4) targets households on income-related benefits living in homes with poor energy efficiency. Qualifying benefits include Universal Credit, Pension Credit, income-based ESA/JSA, Income Support and Child Tax Credits.
The home generally needs to be EPC band D, E, F or G. Owner-occupiers and private tenants with landlord permission qualify; social tenants are generally covered through their landlord.
The Great British Insulation Scheme covers single-measure insulation upgrades and uses different criteria: Council Tax band A-D (England/Scotland) or A-E (Wales), and EPC band D-G.
GBIS doesn't require benefits, broadening access to many low-income working households who fall outside ECO4. Funding levels vary by measure and provider — typically 50-90% of cost.
The simplest measure: top up to 270mm of mineral wool. Typical cost £400-£600 unfunded, often free under ECO4/GBIS. Saves around £180/year on heating in a typical 3-bed semi.
If your loft is currently un-insulated, payback is under 3 years even at full cost. If you have 100-150mm already, top-up payback is longer (5-8 years) but still worthwhile.
Around two-thirds of UK homes have cavity walls (built after 1920). Filling them with mineral wool, polystyrene beads or polyurethane foam typically costs £600-£1,500 unfunded.
Saves £200-£400/year. Beware of rare cases where damp-prone or coastal homes have suffered from inappropriate cavity fill — always insist on a CIGA guarantee and a pre-installation survey.
About a third of UK homes (mostly pre-1920) have solid walls. Internal Wall Insulation (IWI) costs £4,000-£12,000; External Wall Insulation (EWI) £8,000-£20,000. ECO4 sometimes funds EWI fully for qualifying homes.
Annual savings of £400-£700 are possible but EWI changes the appearance significantly and requires planning consent in some areas. IWI reduces internal floor area slightly. Get specialist advice on damp risk before proceeding.
Use TrustMark-registered installers and check for PAS 2030 certification. ECO4/GBIS work must use approved installers.
Be cautious — legitimate scheme installers don't usually cold-call. Apply via your energy supplier's ECO portal or a council scheme directly.
Yes — written landlord permission is required for any structural insulation work.
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