EPC Improvements by Budget: £500, £2,000 and £5,000

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 realistic budgets, £500, £2,000 and £5,000, with typical UK costs and the SAP point gains you can reasonably expect. All figures are ranges, because every property is different, and we explain the caveats honestly at the end.

A quick reminder of the scale: an EPC score runs from 1 to 100 SAP points. Band C starts at 69, band D at 55. So a mid-D property at around 60 points typically needs 9 or more points to reach C.

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: £50-£150, typically 1-4 points

The single best pound-for-pound improvement. The EPC records the proportion of fixed lighting outlets with low-energy bulbs, so swap every remaining halogen and incandescent for LEDs. In a house that still has mostly old bulbs, this alone can be worth several points.

Hot water cylinder jacket: £25-£50, typically 1-2 points

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: £150-£450, typically 2-3 points

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. Adding the missing pieces is a small job for a heating engineer and reliably lifts the score.

Draught proofing: £100-£250, typically 1-2 points

Sealing gaps around windows, doors, letterboxes and floors reduces the modelled heat loss. The point gain is modest, but the comfort improvement is immediate and tenants notice it.

Spend the full £500 across these and a property starting in the low 60s can realistically pick up 4-8 points, sometimes enough to cross into C on its own.

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: £400-£700, typically 4-8 points

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: £550-£1,500, typically 5-10 points

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. Cavity fill plus a loft top-up plus the tier-one measures will typically move a property like this comfortably into band C. In our experience, many typical London D-rated homes can reach C for under £2,500 without touching the heating system at all.

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: £2,000-£3,500, typically 5-12 points

If your boiler is a pre-2005 non-condensing unit, replacing it with a modern condensing boiler is the standout measure in this tier. The efficiency jump from around 70% to 90%+ translates into a large SAP gain, particularly in homes where heating dominates the energy use. If your boiler is already a condensing model, replacing it gains little; spend the money elsewhere.

Solar PV, partial install: from around £3,000-£5,000

A smaller solar array (for example 1.5-2.5 kWp) fits this budget and adds points by generating electricity on site. Gains depend on roof orientation, shading and array size. Solar is also one of the few measures that keeps adding value beyond band C, which matters if you are aiming for B.

Secondary glazing: £1,500-£4,000 depending on coverage

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 EPC gain is usually modest, typically 1-3 points, so treat it as a comfort and compliance measure rather than a points machine.

Summary table

All figures are typical UK ranges and depend on property size, access and starting condition.

The honest caveats

Before you build a spreadsheet from the table above, four things to keep in mind.

Gains depend on your starting point. A measure that adds 8 points to an uninsulated 1930s semi might add 2 to 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 worth 6 points each will usually deliver less than 12 together. If you need to hit a specific band, ask an assessor to model the combination rather than adding up ranges.

Free funding may be available. ECO4 funds insulation and heating measures for eligible lower-income and vulnerable households, and the Great British Insulation Scheme covers single insulation measures for homes in lower council tax bands with poorer ratings. Check eligibility before paying privately, because the same loft top-up or cavity fill might cost you nothing.

You need a fresh EPC afterwards. Improvements only count once a new assessment is lodged on the register. Budget for a new EPC at the end of the project to evidence the rating you have paid for.

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-accredited EPCs across all 32 London boroughs from £49, with full pricing here. Standard delivery is 72 hours, or next-day for £12 extra, and every report comes with a clear improvement list you can plan and budget against.