Cheapest Ways to Improve Your EPC Rating: Top 5 Under £500

The five cheapest EPC improvements, LED lighting, draught-proofing, a hot water cylinder jacket, heating controls, and loft insulation, collectively cost under £500 for many London homes and can add 8–15 SAP points. For properties at the top of band D, this is often enough to reach C.

Why cheap improvements matter

Most of the marketing attention around EPC improvements focuses on heat pumps, external wall insulation, and solar panels, measures that cost £5,000–£20,000. These are important for reaching band B or A, but for the majority of London landlords and homeowners who need to move from E to D, or D to C, the cheap measures are where to start.

The logic is simple: do the cheap things first. They often deliver enough points. If they don't, you've made the building more efficient before the expensive measures, which maximises their effectiveness.

The five best improvements under £500

1. LED lighting throughout, £50–£150, adds 1–4 SAP points

RdSAP 10 credits the proportion of light fittings that are low-energy. If all your fixed fittings are LED, you get maximum lighting credit. If none are, you get minimum credit.

The difference is worth 2–4 SAP points for a typical 3-bed house with 15–20 light fittings. The cost to replace 20 GU10 halogen downlights with LED equivalents: roughly £60–£100 for the bulbs. Replacing older bayonet or Edison screw fittings: similar cost.

Tip: The assessor counts fixed light fittings (ceiling roses, wall lights, downlights). Plug-in lamps on tables don't count. Ensure all fixed fittings have low-energy bulbs in place at the time of the assessment.

The point gain is highest if you're replacing halogens (GU10 spotlights), these are treated as high-energy fittings. A property where all halogens are replaced with LED equivalents can gain 3–4 points.

2. Loft insulation to 270mm, £400–£600, adds 4–8 SAP points

If you have an accessible pitched loft with less than 270mm of insulation, topping it up is the single highest-impact action under £500 (or free under ECO4/GBIS, see below).

The assessment credits insulation depth, measured at the time of the visit. Ensure the loft is accessible for the assessor and the insulation is freshly laid and at depth.

Free routes:

• ECO4: Fully funded for benefit-receiving households in D–G properties
• GBIS: Funded for properties in council tax bands A–D without benefit requirement

If you qualify for either scheme, this is effectively free and should be your first action. Apply through your energy supplier.

3. Draught-proofing, £80–£200, adds 1–2 SAP points

Draught-proofing reduces the measured air leakage rate used in the SAP calculation. Gaps around windows, doors, skirting boards, loft hatches, and pipework all allow cold air in and warm air out.

RdSAP 10 doesn't separately survey draught-proofing as an installation item, it's captured as part of the overall air permeability assessment. However, draught-proofing is listed as a recommended improvement on most EPCs for pre-1980 properties, and its presence is noted by an assessor.

What to tackle:

• Loft hatch: fit a 25mm insulated board cover (£15–£30 DIY)
• External doors: fit brush or rubber seal strips (£5–£10 per door)
• Sash windows: fit brush strip around the frame (£15–£25 per window)
• Chimney (if unused): fit a chimney balloon or draught excluder (£20–£30)
• Letterbox: fit an insulating cover (£5–£10)

Total for a typical London 3-bed terrace: £100–£200 DIY, or £150–£300 with a draught-proofing installer.

4. Hot water cylinder jacket, £15–£25, adds 1–2 SAP points

If your property has a separate hot water storage cylinder (rather than a combi boiler which heats water on demand), a well-insulated jacket dramatically reduces standing heat loss.

An uninsulated cylinder loses 2–4 kWh per day to the surrounding air, useful heat wasted. RdSAP 10 assesses cylinder insulation separately and adds points for adequate jacket depth (80mm+ mineral wool is the threshold for full credit).

Check:

• Does your cylinder have a jacket? (A white or silver foil-wrapped jacket around the outside)
• Is it 80mm thick? (Check by feel, a thin jacket is 25mm, a proper one is 80mm+)

If not insulated or under-insulated: a new cylinder jacket costs £15–£25 from a DIY store and takes 30 minutes to fit. This is the highest point-gain-per-pound improvement available.

5. Heating controls, £150–£350 installed, adds 1–3 SAP points

RdSAP 10 separately credits three control types:

• Room thermostat: The main heating is controlled by a thermostat in the living area (not just a timer). Adds 1 point if absent.
• Programmer (timer): Heating is on a timed programme, not manual-on-permanent. Adds 0.5–1 point.
• Thermostatic radiator valves (TRVs): Each radiator can be individually controlled. Adds 0.5–1 point.

If all three are already present, there's nothing to add. If any are missing, adding them contributes points.

Smart thermostats (Nest, Hive, tado) qualify as room thermostats in RdSAP 10, they don't receive additional credit beyond standard room thermostat credit, but they do qualify.

Installation:

• Smart thermostat + programmer: DIY or £100–£200 installed by a heating engineer
• TRVs (replacing manual valves): £10–£20 per radiator DIY, or £150–£250 for a plumber to do the whole house

Combining the five measures

For a 3-bed London property currently rated D60:

This example crosses into C with just loft insulation and LEDs, the additional measures provide margin and comfort benefits. For a property already at D65 or above, LEDs and loft insulation alone are likely enough.

If loft insulation is funded through ECO4 or GBIS, the remaining measures total under £500.

What won't make the list cheap enough

These are commonly suggested but won't fit under £500 in most cases:

• New boiler: £2,000–£4,000. Very high point gain if replacing old non-condensing, but well above £500.
• Cavity wall insulation: £400–£800 on average, just over the £500 boundary for most properties, but close, and free under ECO4.
• Solar PV: £5,000–£9,000. Transformational for band B, not cheap.
• Double glazing: Window replacement costs £3,000–£8,000 and adds zero points in most London properties (which already have double glazing).

For a full ranked list of all improvements with costs and point gains, see our complete EPC improvement guide. For landlord-specific compliance planning, see our EPC for landlords 2026 guide.

Book an EPC assessment to get your exact SAP score and a personalised improvement plan. We cover all London boroughs, including Hackney, Islington, Ealing, Bromley, Enfield, Croydon, and 28 others, with fixed prices from £49.