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.
This guide is about moving up a band, including from D to C. For what band D itself means and the SAP scores behind every band, see EPC ratings explained.
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), rentals within scope must be rated E or have a valid registered exemption. The confirmed higher standard for 1 October 2030 still requires implementing legislation. 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
| Measure | Why it can affect an EPC | What determines the impact |
|---|---|---|
| LED lighting | Lamp counts and types in permanent fittings are recorded | Existing LED, fluorescent/CFL and incandescent lamps |
| Heating controls | Controls affect calculated heating efficiency | What controls exist now, and the heating system type |
| Draught-proofing | Reduces uncontrolled heat loss | Existing air-tightness and where the gaps are |
| Hot-water cylinder insulation | Cylinder insulation type and thickness are recorded | Whether the cylinder is currently uninsulated or thinly insulated |
| Loft insulation | Reduces heat loss through the roof | Existing depth, roof construction, and whether it can be inspected |
| Cavity wall insulation | May reduce wall heat loss where the walls are suitable | Wall construction, whether the cavity is already filled, property geometry |
| Boiler replacement | Heating efficiency is a major input | The existing system, its age and type, and the fuel |
| Solid wall insulation | Addresses the largest heat-loss element in a solid-wall home | Wall area relative to the dwelling, and internal vs external approach |
| Solar PV | On-site generation offsets calculated energy use | System size, orientation, shading and roof area |
| Heat pump | Changes the heating system and its fuel entirely | What it replaces, the fuel it displaces and the dwelling fabric |
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:
- Cavity wall insulation, where the cavity is unfilled and suitable
- Top up loft insulation
- 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.
Funding for suitable insulation may be available, but check current eligibility and delivery capacity. GBIS has ended. 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)
GBIS ended on 31 March 2026. ECO4 ends on 31 December 2026, and funded work has to be finished by then. Check eligibility and actual funding availability with a supplier or local authority before committing to work.
Great British Insulation Scheme (GBIS)
GBIS ended on 31 March 2026. It is not a current application route.
Boiler Upgrade Scheme (BUS)
The scheme offers £7,500 towards an eligible air-to-water heat pump. EPC C is not a general eligibility requirement. Check the current GOV.UK eligibility rules and speak to an MCS-certified installer about suitability and the application.
What the EPC calculation considers
The software models the whole dwelling: construction and insulation, dimensions, heating and controls, hot water, ventilation, glazing, renewables and lighting. There is no universal ranking that predicts the effect of an improvement for every property.
Cosmetic decoration does not itself improve the recorded energy features. For energy upgrades, use the property-specific assessment and suitable installation advice.
Getting a new EPC after improvements
Improvements do not automatically invalidate an existing EPC. A new assessment can record completed work when there is a reason to update the rating. Keep supporting evidence; the new result is not guaranteed to be higher.
An assessment does not itself create energy savings. See our guide prices and decide whether an updated certificate is needed. We cover all London boroughs and typically turn around certificates within 72 hours of the visit. Book here.
What it costs
An EPC is priced by the home’s internal floor area. Guide prices:
- Up to 40 m²Studios and compact flats£65
- 41–55 m²1-bedroom flats£75
- 56–75 m²2-bedroom flats and small homes£85
- 76–95 m²2–3-bedroom homes£95
- 96–115 m²3–4-bedroom houses£105
- 116 m² and overLarge homes, 4+ bedroomsfrom£120
A floor plan at the same visit saves up to £35. Same-day lodgement is £15 extra, and a next-day visit with the EPC lodged that day is £35 extra. Your exact price is confirmed before you book.
See every priceFrequently asked questions
How many SAP points do I need to move from D to C?
Band D runs from 55 to 68 SAP points and band C starts at 69, so the gap depends entirely on where your property sits within D. Your EPC shows the exact current score and an indicative rating after the recommended measures for that specific property, which is the figure to work from rather than any general rule.
Can I improve my EPC rating without spending much?
Yes. LED lighting, heating controls and draught-proofing are the low-cost starting points, and their effect depends on the property and the methodology used for the assessment. How much they move a particular rating is calculated from the whole dwelling, so check the indicative figures in the suggested improvements on your own EPC rather than assuming a fixed gain.
Does a new boiler improve my EPC rating?
It can, where the existing boiler is an older non-condensing type — heating efficiency is a significant input to the calculation. If the boiler is already a modern condensing unit, replacing it is unlikely to change the rating much, and insulation is usually the better use of the money. The actual effect is property-specific.
How do I know if my walls are cavity or solid?
Properties built after 1920 and before roughly 1990 typically have cavity walls. Victorian and Edwardian buildings (pre-1919) generally have solid 9-inch brick walls. Measure wall thickness at a window reveal, under 260mm indicates solid brick; 280–330mm indicates cavity construction.
Will solar panels improve my EPC rating?
It can, because on-site generation offsets the calculated energy use of the dwelling. Solar PV is often the measure with the largest single effect where a property has suitable roof area and orientation, and it is frequently the practical route for solid-wall homes where wall insulation is difficult. How much it moves a particular rating depends on system size, orientation, shading and the dwelling itself.
In your area
Ratings from EPCs lodged for existing homes, 01/01/2023 to 12/10/2026, from the GOV.UK register.
Sources
- Apply for the Boiler Upgrade Scheme: what you can get, GOV.UK. Checked 29/10/2026.£7,500 towards an air source or ground source heat pump; £5,000 towards a biomass boiler.
- Extending the ECO4 end date: government response, GOV.UK (DESNZ). Checked 29/10/2026.ECO4 extended by 9 months to end on 31 December 2026; GBIS ended on 31 March 2026.
Crown copyright material is used under the Open Government Licence v3.0.
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