EPC Improvement Costs 2026: The Complete Price Guide for Every Upgrade

This is the definitive price guide for every EPC improvement available to UK landlords in 2026. For each measure, we list the realistic cost range, the typical SAP point gain, and the cost per SAP point — the metric that matters most when you are working within the £10,000 cost cap and need to maximise every pound spent.

All costs include installation and reflect 2026 pricing in England and Wales. VAT on qualifying energy-saving materials is currently 0% (until at least March 2027). SAP point gains are typical ranges — your actual gain depends on the property’s starting condition, construction type and existing measures.

How to read this guide

Each improvement is listed with three key numbers:

• Cost: The typical installed price range for a standard residential property in 2026
• SAP gain: The typical number of SAP points added to the property’s energy performance score
• Cost per point: The cost divided by the SAP point gain — lower is better. This tells you which improvements give you the most compliance progress per pound spent.

We have organised improvements into four tiers by cost, from cheapest to most expensive. For landlords facing the October 2030 deadline, the strategy is simple: start at the top and work down until you reach 69 SAP points (Band C).

Quick wins: under £500

These are the improvements with the lowest absolute cost and often the best cost-per-point ratio. Every landlord should consider these first, regardless of budget.

Hot water cylinder insulation

• Cost: £20–£50
• SAP gain: +1–2 points
• Cost per point: £15–£35

A simple insulation jacket for an uninsulated or poorly insulated hot water cylinder. Only applicable to properties with a hot water tank (not combi boilers). This is the cheapest EPC improvement that exists — a £20 jacket from a DIY store can add a full SAP point.

Pipe insulation

• Cost: £50–£100
• SAP gain: +0.5–1 point
• Cost per point: £50–£200

Insulating exposed hot water pipes in unheated spaces (loft, under floor, garage). Small gain but very cheap and easy to do yourself.

LED lighting

• Cost: £50–£200
• SAP gain: +1–2 points
• Cost per point: £30–£150

Replacing all remaining halogen or CFL bulbs with LEDs. The SAP model considers lighting energy, and LEDs use 80–90% less than halogens. For a typical 3-bedroom property, replacing 10–15 non-LED bulbs costs under £100 and can add 1–2 points. Many properties have already been upgraded, so check your EPC recommendations first.

Draught proofing

• Cost: £100–£300
• SAP gain: +1–3 points
• Cost per point: £50–£150

Sealing gaps around doors, windows, loft hatches, letterboxes and floorboards. The SAP model accounts for air permeability, and reducing draughts in an older property can deliver meaningful gains. Professional draught proofing of all doors and windows in a 3-bed terrace typically costs £200–£300.

Loft insulation top-up

• Cost: £300–£500
• SAP gain: +4–7 points
• Cost per point: £50–£100

Topping up existing loft insulation to 270mm (the current building regulation standard). Many older properties have 100mm or less. This is consistently one of the best-value EPC improvements available. If your property has a loft and it is not at 270mm, this should be your first call.

Mid-range: £500–£2,000

These improvements require professional installation but remain well within the £10,000 cost cap. They deliver substantial SAP point gains and are typically the core of a compliance strategy.

Heating controls and TRVs

• Cost: £200–£500
• SAP gain: +2–4 points
• Cost per point: £75–£175

Adding or upgrading a programmer, room thermostat and thermostatic radiator valves (TRVs). If the property has a boiler but no programmer, or has a basic timer but no room thermostat, upgrading the controls can add meaningful SAP points. Smart thermostats (Nest, Hive, tado) count the same as conventional programmable thermostats in SAP, but will score higher under the future Smart Readiness metric.

Floor insulation

• Cost: £500–£1,500
• SAP gain: +2–4 points
• Cost per point: £175–£500

Insulating suspended timber floors from below (via a cellar or crawl space) or laying insulation over a solid floor. The gain varies with floor type and area. Properties with accessible underfloor voids are cheaper to treat. Solid concrete floors require overlay insulation, which raises floor levels and may affect door clearances.

Cavity wall insulation

• Cost: £800–£1,600
• SAP gain: +5–8 points
• Cost per point: £130–£250

Filling empty cavity walls with mineral wool, polystyrene beads or foam. This is one of the highest-value improvements for any property built between the 1930s and 1990s with unfilled cavities. The installation is typically completed in a single day by drilling small holes in the external wall and injecting the insulation material.

Secondary glazing

• Cost: £1,200–£1,800
• SAP gain: +1–3 points
• Cost per point: £500–£1,200

Adding a secondary layer of glazing inside existing windows. Primarily relevant for listed buildings or conservation areas where replacing windows is restricted. The SAP gain is modest compared to full double glazing, but secondary glazing is significantly cheaper and may be the only option where planning constraints apply.

Major works: £2,000–£10,000

These are significant investments that deliver substantial SAP point gains. They are typically needed for properties starting at Band E or below, or Band D properties where cheaper measures are not sufficient to close the gap.

New condensing boiler

• Cost: £2,000–£3,500
• SAP gain: +2–5 points
• Cost per point: £500–£1,200

Replacing an old non-condensing gas boiler with a modern A-rated condensing boiler. The SAP gain depends on the age and efficiency of the existing boiler. If the current boiler is already condensing, the gain will be minimal. Note: under the new four-metric EPC system, a gas boiler alone will not satisfy the Fabric Performance metric — consider whether a heat pump might be a better long-term investment.

Double glazing

• Cost: £3,000–£8,000
• SAP gain: +2–6 points
• Cost per point: £700–£2,000

Replacing single-glazed or old double-glazed windows with modern double glazing. The cost varies enormously with the number of windows and the property size. A 2-bed flat might cost £3,000–£4,000; a 4-bed detached house could reach £8,000. The SAP gain is moderate relative to the cost, making this one of the less efficient improvements on a cost-per-point basis. However, glazing contributes directly to the Fabric Performance metric under the new EPC system.

Solar PV

• Cost: £5,000–£8,000
• SAP gain: +4–8 points
• Cost per point: £750–£1,500

A 4kW rooftop solar PV system. The SAP gain depends on roof orientation (south-facing is best), pitch and shading. Solar PV adds long-term value to the property through Smart Export Guarantee (SEG) payments and tenant appeal, but it is not the cheapest route to SAP points. Best deployed as a supplementary measure after insulation and heating improvements.

Premium works: £10,000+

These improvements are the most powerful in terms of SAP point gains but carry high absolute costs. Grant funding (particularly the £7,500 BUS voucher for heat pumps) can bring the landlord’s net cost within the £10,000 cap.

Air source heat pump

• Cost: £13,200 average installed (£10,000–£18,000 range)
• After BUS grant: ~£5,700 (£2,500–£10,500 range)
• SAP gain: +10–20 points
• Cost per point (after grant): £200–£700

Replacing a gas or oil boiler with an air source heat pump. This is the single most impactful EPC improvement available. A 15-point gain can move a property from Band D to Band C in one step, or from Band E to high Band D. With the £7,500 BUS grant, the net cost is often comparable to a premium gas boiler installation.

For full details on heat pumps for landlords, see our heat pump EPC improvement guide.

External wall insulation (EWI)

• Cost: £8,000–£15,000
• SAP gain: +8–15 points
• Cost per point: £700–£1,300

Cladding the exterior walls with insulation boards and a render finish. This is the primary option for solid-walled properties (pre-1930s) that have no cavity to fill. EWI delivers large SAP gains and dramatically improves thermal comfort, but it is expensive and changes the property’s external appearance. Planning permission may be required in conservation areas.

Ground source heat pump

• Cost: £15,000–£30,000
• After BUS grant: £7,500–£22,500
• SAP gain: +15–25 points
• Cost per point (after grant): £400–£1,200

More efficient than air source but requires garden space for ground loops or a borehole. Rarely cost-effective for standard rental properties due to the high installation cost, but may be suitable for rural properties with large gardens or where air source heat pumps would cause noise issues.

Cost-per-SAP-point ranking

This table ranks every improvement from cheapest to most expensive per SAP point gained — the key metric for maximising your £10,000 budget:

The message is clear: cheap fabric improvements (insulation, draught proofing, lighting) deliver far more SAP points per pound than expensive measures like glazing or solar PV. Start from the top of this list and work down.

The £10,000 cost cap: how to prioritise spending

The cost cap means you are only required to spend up to £10,000 of your own money on qualifying improvements. If the property still cannot reach Band C after £10,000, you can register an exemption. This makes prioritisation essential — you need to extract the maximum SAP point gain from your budget.

A model compliance strategy for a Band D property (SAP 58):

• Loft insulation top-up: £400 → +5 points (SAP 63)
• Draught proofing: £200 → +2 points (SAP 65)
• LED lighting: £100 → +1 point (SAP 66)
• Heating controls/TRVs: £350 → +3 points (SAP 69 — Band C)

For properties starting at Band E (SAP 39–54) or Band F (SAP 21–38), the quick wins alone will not be sufficient. These properties typically need mid-range measures (cavity wall insulation) and potentially major works (heat pump or external wall insulation) to reach Band C. The cost cap provides a backstop: if £10,000 of qualifying spend cannot get you there, the exemption route is available.

For the cheapest route from Band D to Band C specifically, see our dedicated guide: EPC D to C: the cheapest route to compliance.

How grants reduce your out-of-pocket costs

Grants do not count towards the £10,000 cost cap because they are not your money. This effectively stretches your compliance budget well beyond £10,000:

• BUS grant (£7,500): A £13,200 heat pump costs you £5,700 after the grant. Only £5,700 counts towards your cap.
• ECO4: Fully funded insulation through energy company obligation. £0 from your pocket, £0 towards your cap.
• Warm Homes: Local Grant (first property): 100% funded. £0 from your pocket.
• Warm Homes: Local Grant (subsequent properties): 50% funded. You pay 50%, and only that half counts towards your cap.

The optimal strategy: exhaust all grant funding first (ECO4 if your tenant qualifies, Warm Homes: Local Grant, BUS), then self-fund the remaining improvements in cost-per-point order. For a complete guide to every available grant, see home energy grants UK 2026.

For properties with cavity walls and a gas boiler, the combination of ECO4-funded cavity wall insulation and a BUS-funded heat pump can deliver 15–28 SAP points at minimal personal cost. Add self-funded loft insulation (£400) and LED lighting (£100) and you have a comprehensive upgrade for under £500 out of pocket. For properties that need loft insulation specifically, see our loft insulation guide for landlords. For cavity wall insulation details, see our cavity wall insulation guide.