How to Improve Your EPC Rating: Costs and Point Gains

The most cost-effective path to a better EPC rating generally starts with LED lighting and loft insulation, then cavity wall insulation where the property is suitable. Solid-wall properties are considerably more expensive to improve, because the cheap wall measure is not available to them.

Why improving your EPC rating matters in 2026

An EPC rating affects three things directly: legal lettability, saleability, and energy bills. Under the Minimum Energy Efficiency Standards (MEES), rental properties must be rated E or above today, and the proposed upgrade to band C — phased, with an aim of 2030 — is close enough that landlords acting now avoid the future rush. See our EPC for landlords guide for the full compliance picture.

For sellers, the rating is one of the things buyers and their advisers look at, and a better rating is one less question to answer during a sale. See our EPC for selling guide for pre-sale strategy.

What each measure does, and what decides its impact

Measures are listed roughly cheapest-first. Actual installation costs vary materially by property, specification, access, installer and location, so get quotes from suitably qualified installers rather than working from a published range.

D-to-C paths for common London property types

Victorian and Edwardian terraces (pre-1919, solid walls)

The hardest property type to upgrade affordably, because solid brick walls cannot be cavity-filled and the wall is usually the largest heat-loss element.

If the boiler is an older non-condensing type, replacing it is usually the largest single lever available, because heating efficiency is a major input. Combined with loft insulation, heating controls and LED lighting, that is the cheapest package for this property type.

If the boiler is already a modern condensing unit, that lever is largely spent. What remains is the fabric — wall insulation — or on-site generation such as solar PV. Both are substantially more expensive, and external wall insulation may need planning consent, or be restricted entirely in a conservation area.

For inner-London Victorian stock in Hackney, Islington, Lambeth and Wandsworth, the practical question is usually whether solar PV is viable, since it avoids touching protected elevations.

1930s–1970s semis (cavity walls)

Usually the most straightforward London properties to upgrade, because an unfilled cavity is comparatively cheap to insulate. Common in Ealing, Croydon, Bromley, Enfield and Barnet.

The usual order of works:

1. Cavity wall insulation, where the cavity is unfilled and suitable
2. Top up loft insulation
3. LED lighting throughout

This is normally the cheapest combination available to this property type, which is why these homes tend to have the shortest route to a higher band.

Cavity wall insulation and loft insulation may both be free under ECO4 or GBIS for eligible households. See our cavity wall insulation guide and loft insulation guide for details.

Post-war flats (1945–1980, Tower Hamlets, Newham)

Purpose-built flats from this era often have concrete construction and communal or district heating. The EPC depends heavily on the heating system:

• Electric storage heaters: typically D or E, replacing with a gas combi or modern heat pump is the highest-impact single measure
• Communal gas: often C already; individual leaseholders have limited room for improvement
• District heating: varies enormously by scheme vintage

For leaseholders, speak to your freeholder about communal system upgrades and check what individual measures, glazing upgrades, cylinder insulation, are within your control.

Free and subsidised schemes in 2026

ECO4 (Energy Company Obligation)

ECO4 funds insulation and heating upgrades for eligible households:

• Households receiving means-tested benefits (Universal Credit, Pension Credit, Housing Benefit)
• Private tenants or owner-occupiers in D–G-rated properties
• Some local authority referral routes (check your borough council)

Covered measures: loft insulation, cavity wall insulation, external wall insulation, heat pump installation, all fully funded. Apply through your energy supplier or a registered ECO4 installer.

Great British Insulation Scheme (GBIS)

Broader than ECO4: covers properties in council tax bands A–D without requiring benefit receipt. Funds a single insulation measure (loft or cavity wall). Apply through your energy supplier.

Boiler Upgrade Scheme (BUS)

£7,500 grant toward an air source heat pump. Requires an in-date EPC rated C or above. If your property is rated D or E, improve the fabric first, commission a new EPC, then apply for BUS.

What RdSAP actually weights most

Understanding how the software scores each factor helps prioritise:

1. Heating system efficiency, the single largest factor. A heat pump scores far better than storage heaters.
2. Fabric heat loss, wall, roof, and floor U-values.
3. Hot water efficiency, insulated cylinder with modern boiler scores well; immersion heaters score poorly.
4. Renewable generation, solar PV directly reduces modelled energy demand.
5. Lighting, proportion of low-energy (LED) fittings.

The software does not credit cosmetic changes, repainting, or general refurbishment. It does not significantly credit new double glazing when the property already has double glazing, window replacement rarely makes a meaningful difference to the rating in most London homes.

Getting a new EPC after improvements

Any improvements since your last EPC was issued warrant a new assessment. The new certificate replaces the old one on the government register. There's no minimum waiting period, commission as soon as works are complete.

For most single-measure improvements, the cost of a new assessment (guide prices from £65 at L&D Energy) is recovered within the first month of energy savings. We cover all London boroughs and typically turn around certificates within 72 hours of the visit. Book here.