Improving an EPC rating does not have to mean a heat pump and a five-figure bill. Most homes climb the scale through a series of modest, well-chosen measures, and the right ones depend almost entirely on your budget and what the property already has.
This guide breaks the options into three budgets — roughly £500, £2,000 and £5,000 — and explains what each measure does and what decides how much it helps.
A quick reminder of the scale: an EPC score runs from 1 to 100 SAP points, band D starts at 55 and band C at 69. How far you have to travel depends on where your property currently sits, which is on your certificate.
Under £500: the quick wins
If your budget is a few hundred pounds, focus on lighting, controls and heat retention. None of these require structural work, and most can be done in a weekend or by a handyman.
LED lighting throughout
An option to consider where older lamps remain. RdSAP records lamp counts and types in permanent fittings, distinguishing LED, fluorescent/CFL and incandescent lamps. The effect is largest in a house that still has mostly old bulbs — and negligible in one already fully converted.
Hot water cylinder jacket
If you have a hot water cylinder with thin or no insulation, an 80mm jacket is one of the cheapest measures in existence. If your cylinder is already factory-insulated foam, or you have a combi boiler with no cylinder, this does not apply.
Heating controls
RdSAP rewards a full set of controls: a programmer, a room thermostat and thermostatic radiator valves (TRVs). Many older systems are missing the room thermostat or TRVs. A heating engineer can advise on suitable controls. The effect on the EPC depends on the system and whole-property calculation.
Draught proofing
Suitable draught-proofing can reduce uncontrolled air leakage. RdSAP records window and door draught-proofing under its conventions; not every DIY measure has a separate modelled effect. Preserve intentional ventilation.
A £500 budget does not imply a fixed point gain or a move to C. Use the assessed property and suitable installation advice to decide what to prioritise.
Under £2,000: insulation does the heavy lifting
With up to £2,000, you can do everything in the first tier and add one or both of the highest-impact insulation measures.
Loft insulation top-up to 270mm
If your loft has less than 100mm of insulation, topping it up to the recommended 270mm is one of the biggest single gains available. The materials are cheap, the labour is straightforward, and the gain is largest for properties starting with little or no insulation. We cover the details in our guide to loft insulation and EPC ratings.
Cavity wall insulation
Where the property has unfilled cavity walls, filling them is usually the largest gain in this price range. Most homes built between roughly 1930 and 1990 have cavities, and many remain unfilled. A borescope check confirms suitability, and exposure to driving rain needs assessing first. Our cavity wall insulation guide covers when it is and is not a good idea.
Putting the tier together
A common London scenario, typical of the inter-war and 1950s semis across Ealing, Croydon and Enfield: a mid-terrace rated mid-D, with unfilled cavities, 100mm of loft insulation, partial LED lighting and no TRVs. These measures may be worth investigating, but this is an illustration, not a verified case study or a prediction of cost or rating. The specific geometry, heating and installed insulation must be assessed.
For more low-cost ideas, see our roundup of the cheapest ways to improve an EPC.
Under £5,000: heating and bigger projects
Above £2,000, the options shift to the heating system and the building fabric's harder problems.
Replacing an old non-condensing boiler
If your boiler is an older non-condensing unit, replacing it with a modern condensing boiler is the standout measure in this tier, because heating efficiency is a major input to the calculation and heating usually dominates a home's energy use. If your boiler is already a condensing model, replacing it changes little — spend the money elsewhere.
Solar PV, partial install
A smaller solar array fits this budget and helps by generating electricity on site. How much depends on roof orientation, shading and array size. Solar is also one of the few measures that keeps helping beyond band C, which matters if you are aiming for B. Our guide to solar panels and your EPC rating works through how many points different systems add.
Secondary glazing
Where full double glazing is impractical or not permitted, for example in conservation areas, secondary glazing improves the modelled window performance and cuts draughts and noise. The effect on the rating is usually modest, so treat it as a comfort and compliance measure rather than a route to a new band.
Summary table
Measures roughly cheapest-first. What each one does, and what decides how much it helps your particular property:
| 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 |
| Hot water cylinder jacket | Cylinder insulation type and thickness are recorded | Whether the cylinder is bare, thinly insulated or already foam-insulated |
| Heating controls | Controls affect calculated heating efficiency | Which of thermostat, programmer and TRVs already exist |
| Draught proofing | Reduces uncontrolled heat loss | Existing air-tightness and where the gaps are |
| Loft insulation top-up | Reduces heat loss through the roof | Existing depth, roof construction, whether it can be inspected |
| Cavity wall insulation | May reduce wall heat loss where walls are suitable | Wall construction, whether the cavity is already filled, geometry |
| Condensing boiler | Heating efficiency is a major input | The existing system, its age and type, and the fuel |
| Secondary glazing | Improves modelled window performance | Existing glazing, and how much of the property is covered |
Installation costs vary materially by property, specification, access, installer and location, so get quotes from suitably qualified installers. We carry out the EPC assessment — we do not quote for or install this work.
The honest caveats
Before you build a spreadsheet from the table above, four things to keep in mind.
Gains depend on your starting point. The same measure can matter a great deal in an uninsulated 1930s semi and barely register in a 1990s flat. The lower your starting rating, the bigger the gains tend to be, because the model rewards fixing the worst problems first.
Points are not simply additive. RdSAP models the whole dwelling, so measures interact. Insulating the walls reduces heating demand, which in turn shrinks the benefit of a more efficient boiler. Two measures will usually deliver less together than they would apart. If you need to hit a specific band, ask an assessor to model the combination rather than adding up estimates.
Check current funding. GBIS ended on 31 March 2026. ECO4 ends on 31 December 2026, and funded work has to be finished by then; eligibility and actual availability must be checked with a supplier or local authority. See the official scheme update.
Recording a changed property. Improvements do not automatically invalidate an existing EPC. A fresh assessment can record the completed work and establish the resulting rating; no particular outcome is promised.
Where to start
Start with the certificate, not the chequebook. Your current EPC's recommendations section, or a fresh assessment if the certificate is old, tells you which of these measures apply to your property and roughly what each is worth. Then work up the budget tiers in order: the under-£500 measures first, insulation second, heating last.
L&D Energy provides Elmhurst and Quidos accredited EPCs across all 32 London boroughs with guide prices from £65 — see full pricing here. Standard lodgement is within 72 hours, or the same day for £15 extra, and every report comes with a clear improvement list you can plan and budget against.
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 much does it cost to improve an EPC from D to C?
There is no reliable D-to-C price without assessing the building and obtaining installation quotes. The current score, construction and existing systems all matter; no budget guarantees a band.
What is the cheapest way to gain EPC points?
LED lighting throughout is usually the cheapest measure, and a hot water cylinder jacket is excellent value where the cylinder is uninsulated. Their effect depends on what is already present, the property and the assessment methodology. How much either moves your particular rating is shown in the suggested improvements on your EPC.
Do EPC points from different measures add up?
Not in a simple way. RdSAP models the whole property, so measures interact. For example, improving insulation reduces the heating demand, which changes the impact of a more efficient boiler. Do not rely on generic point gains, and ask an assessor to model your specific property if a target rating matters.
Can I get any of these improvements funded for free?
GBIS ended on 31 March 2026. ECO4 ends on 31 December 2026, and funded work has to be finished by then; eligibility and actual availability must be checked with a supplier or local authority.
Do I need a new EPC after making improvements?
Improvements do not automatically invalidate an EPC. A new assessment and lodgement are needed to record a new rating; the old certificate remains historical on the register after replacement. A new rating is not guaranteed to be higher.
In your area
Ratings from EPCs lodged for existing homes, 01/01/2023 to 12/10/2026, from the GOV.UK register.
Sources
- 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.
- 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.
Crown copyright material is used under the Open Government Licence v3.0.
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