Whether you're a homeowner trying to cut energy bills or a landlord meeting minimum EPC requirements, the first question is always the same: how much will it cost?
EPC improvements range from under £50 for a hot water cylinder jacket to over £15,000 for a heat pump or external wall insulation. The right combination depends on your property, your current rating, and how far you need to move.
This guide covers every common EPC improvement, with realistic 2026 UK prices, expected SAP point gains, and practical advice on where to start. Use our EPC checker to see your current rating and the specific recommendations for your property before you plan any work.
Master cost table: every EPC improvement at a glance
This table summarises the most common EPC improvements, what they typically cost, and how many SAP points they can add. The "Best For" column shows which EPC bands benefit most from each measure.
| Improvement | Typical Cost | EPC Points Gain | Best For |
|---|---|---|---|
| LED lighting | £50–£200 | 1–3 | All bands |
| Draught proofing | £100–£300 | 1–3 | All bands |
| Hot water cylinder jacket | £20–£50 | 1–3 | E, F, G |
| Loft insulation (top-up to 270mm) | £300–£600 | 3–8 | D, E, F, G |
| Loft insulation (new, 270mm) | £400–£1,200 | 5–15 | F, G |
| Heating controls (TRVs, stat, programmer) | £200–£500 | 3–8 | D, E, F |
| Cavity wall insulation | £1,000–£2,500 | 5–15 | D, E, F |
| Floor insulation | £2,000–£6,000 | 1–5 | D, E, F |
| New condensing boiler | £2,000–£4,000 | 5–15 | D, E, F |
| Double glazing | £4,000–£8,000 | 3–8 | E, F, G |
| Solid wall insulation (internal) | £5,000–£10,000 | 10–20 | E, F, G |
| Solid wall insulation (external) | £10,000–£20,000 | 10–20 | E, F, G |
| Air source heat pump | £8,000–£15,000 | 10–30 | C, D, E |
| Ground source heat pump | £15,000–£30,000 | 15–40 | C, D, E |
| Solar PV (4kW system) | £5,000–£8,000 | 5–15 | All bands |
| Solar thermal | £3,000–£5,000 | 3–8 | C, D, E |
Costs are typical installed prices for 2026 in the UK. Actual prices vary by region, property size, and installer. SAP point gains depend on the property and what's already in place — these are representative ranges.
Low-cost improvements: under £500
These are the first improvements to consider. They're affordable, often quick to install, and can be enough to push a property into the next band if you're close to the threshold. For a deeper look at budget options, see our guide to the cheapest ways to improve your EPC.
LED lighting (£50–£200 | 1–3 SAP points)
Replacing all halogen or CFL bulbs with LEDs is one of the simplest EPC wins. The SAP calculation considers the proportion of fixed lighting that uses low-energy bulbs. If your EPC report says less than 75% of your lighting is low-energy, upgrading the remaining fittings should gain you points.
The cost depends on how many fittings you need to replace. In most homes, £50–£200 covers the full house. This is worth doing regardless of your EPC band.
Draught proofing (£100–£300 | 1–3 SAP points)
Draught proofing covers sealing gaps around windows, doors, letterboxes, chimneys, and pipework. Self-fit draught strips cost as little as £30–£50 in materials, but a professional job covering the whole house typically runs £100–£300.
The EPC impact is modest (1–3 points), but it stacks well with other low-cost measures. It also makes the home noticeably more comfortable.
Hot water cylinder jacket (£20–£50 | 1–3 SAP points)
If you have a hot water cylinder (tank) with no jacket or a thin, damaged one, a new 80mm British Standard jacket is one of the cheapest improvements available. At £20–£50, this is almost always worth doing. The SAP score penalty for an uninsulated cylinder is surprisingly high.
This only applies if you have a cylinder. Homes with combi boilers don't have one and won't benefit from this measure.
Heating controls upgrade (£200–£500 | 3–8 SAP points)
Heating controls include thermostatic radiator valves (TRVs), a room thermostat, and a programmer or timer. If your EPC report lists any of these as missing, adding them is highly cost-effective.
- TRVs on all radiators (except the room with the thermostat): £100–£250 installed
- Room thermostat: £80–£150 installed
- Programmer/timer: £80–£150 installed
- Smart thermostat (e.g. Nest, Hive): £150–£300 installed
Moving from "no time or temperature control" to a full set of controls can gain 5–8 SAP points. Even partial upgrades help.
Loft insulation top-up (£300–£600 | 3–8 SAP points)
Many homes already have some loft insulation, but it may only be 100mm or less. The current standard is 270mm of mineral wool. Topping up from 100mm to 270mm typically costs £300–£600 for a standard loft and can gain 3–8 SAP points.
If your loft is accessible and not boarded, this is one of the best-value upgrades available. See our loft insulation guide for more detail on when it works and when it doesn't.
Medium-cost improvements: £500–£2,000
These improvements require more investment but often deliver the biggest gains per pound for properties rated D, E, or F.
Loft insulation — full new installation (£400–£1,200 | 5–15 SAP points)
If your home has no loft insulation at all, a full 270mm installation can deliver a substantial SAP boost — often 10–15 points for previously uninsulated properties. This is one of the most impactful single measures available.
The cost is slightly higher than a top-up because it involves laying the full depth from scratch, but it's still one of the cheapest high-impact upgrades.
Cavity wall insulation (£1,000–£2,500 | 5–15 SAP points)
Cavity wall insulation is injected into the gap between the inner and outer walls through small holes drilled from the outside. It typically takes a day to complete and costs £1,000–£2,500 depending on the size of the property.
This is one of the most effective single measures for homes built between the 1930s and 1990s that have unfilled cavities. It can gain 5–15 SAP points, sometimes moving a property up a full band on its own. Not all properties are suitable — older solid-wall or narrow-cavity homes may need a different approach.
High-cost improvements: £2,000–£10,000
These are significant investments, but they address the biggest energy-loss factors in most homes: heating efficiency and wall insulation.
Floor insulation (£2,000–£6,000 | 1–5 SAP points)
Insulating a suspended timber floor from below (if there's crawl space access) or adding insulation above the floor typically costs £2,000–£6,000. The SAP impact is more modest than walls or loft (1–5 points), but it can be the difference when you're a few points short of the next band.
Floor insulation works best in combination with other measures. On its own, the point gain may not justify the disruption for homes that only need a small rating improvement.
New condensing boiler (£2,000–£4,000 | 5–15 SAP points)
Replacing an old, inefficient boiler (typically G or F rated, pre-2005) with a modern A-rated condensing boiler usually costs £2,000–£4,000 including installation. The SAP impact depends on how inefficient your current boiler is.
A property with a very old boiler (60–70% efficiency) upgrading to a modern condensing boiler (90%+ efficiency) can gain 10–15 SAP points. If your boiler is already a post-2005 condensing model, the improvement will be much smaller. See our detailed guide on whether a new boiler will improve your EPC.
For landlords and homeowners on a budget, boiler grants may be available through the ECO4 scheme.
Double glazing (£4,000–£8,000 | 3–8 SAP points)
Replacing single-glazed windows with double glazing typically costs £4,000–£8,000 for a whole house, depending on the number and size of windows. The SAP impact is relatively modest (3–8 points) compared to the cost, because windows make up a smaller proportion of total heat loss than walls or roof in most homes.
Double glazing is more cost-effective for EPC purposes when combined with other insulation measures. If you already have double glazing, upgrading to triple glazing gives minimal additional SAP benefit and is rarely worth the cost purely for EPC purposes.
Solid wall insulation — internal (£5,000–£10,000 | 10–20 SAP points)
Internal wall insulation (IWI) involves adding insulation boards to the inside face of external walls. It costs £5,000–£10,000 depending on the area to be covered, and it can add 10–20 SAP points for solid-wall properties.
The disruption is significant — rooms shrink slightly, sockets and radiators need moving, and decoration needs redoing. But for solid-wall properties (typically pre-1930s), this is one of the most impactful measures available. It's often the key to moving from E or F up to D or C.
Premium improvements: £10,000+
These measures offer the largest SAP gains and are typically part of a deep retrofit or a strategy to reach band B or above.
Solid wall insulation — external (£10,000–£20,000 | 10–20 SAP points)
External wall insulation (EWI) wraps the outside of the building with insulation boards and a new render finish. It's more expensive than internal insulation (£10,000–£20,000 for a typical semi-detached or larger), but it avoids losing internal floor space and causes less disruption inside the home.
EWI changes the appearance of the building, so it may need planning permission, particularly in conservation areas. It's most cost-effective for properties with large areas of exposed solid wall and poor current insulation.
Air source heat pump (£8,000–£15,000 | 10–30 SAP points)
Air source heat pumps (ASHPs) extract heat from outdoor air and use it to warm your home. They cost £8,000–£15,000 installed, but the Boiler Upgrade Scheme provides a £7,500 grant, bringing the out-of-pocket cost down to as little as £500–£7,500.
The SAP impact can be substantial — 10–30 points — because the SAP calculation heavily rewards low-carbon heating. An ASHP can move a D-rated property to B or even A in the right circumstances. However, your home needs to be well-insulated for a heat pump to work efficiently, so insulation improvements usually need to come first. Read our full heat pump guide for more detail.
Ground source heat pump (£15,000–£30,000 | 15–40 SAP points)
Ground source heat pumps (GSHPs) are more efficient than air source but significantly more expensive because they require boreholes or ground loops. They cost £15,000–£30,000 and deliver 15–40 SAP points.
The £7,500 Boiler Upgrade Scheme grant applies to GSHPs too, but the remaining cost is still high. These are typically only considered for larger properties, new builds, or deep retrofits where maximum efficiency is the goal.
Solar PV — 4kW system (£5,000–£8,000 | 5–15 SAP points)
A 4kW solar PV system (around 10–12 panels) typically costs £5,000–£8,000 installed in 2026. The SAP benefit varies depending on roof orientation and other factors, but 5–15 points is typical.
Solar PV doesn't just improve your EPC — it also generates electricity that reduces your bills and can be sold back to the grid. The payback period is typically 8–12 years. See our guide on solar panels and EPC ratings for the full picture.
Solar thermal (£3,000–£5,000 | 3–8 SAP points)
Solar thermal panels heat water directly using sunlight. They cost £3,000–£5,000 and typically add 3–8 SAP points. They work best alongside a conventional boiler or heat pump and are most effective in homes with high hot water demand.
Solar PV is generally a better investment for EPC purposes in 2026, because it provides more SAP points per pound and is more versatile.
What does each band jump cost?
The total cost of moving up a band depends on where you start and what your property already has. Here are typical costs based on the most common upgrade combinations:
| Band Jump | Typical Total Cost | Common Improvements |
|---|---|---|
| G to F | £300–£8,000 | Loft insulation, heating controls, lighting |
| F to E | £500–£3,500 | Insulation top-up, basic heating upgrade |
| E to D | £1,000–£5,000 | Cavity walls, boiler, heating controls |
| D to C | £1,000–£5,000 | Insulation, controls, possibly boiler |
| C to B | £3,000–£15,000 | Heat pump, solar PV, advanced insulation |
The wide ranges reflect the huge variation between properties. A G-rated home that simply lacks loft insulation might reach F for £400. Another G-rated home with solid walls, single glazing, and old electric storage heaters could cost £8,000 or more.
For detailed guidance on specific band jumps, see our guides:
Government grants and funding in 2026
Several government schemes can reduce or eliminate the cost of EPC improvements. Eligibility varies, so check each scheme's criteria carefully. Our home energy grants guide has full details.
ECO4 (Energy Company Obligation)
ECO4 funds insulation, heating upgrades, and other energy efficiency measures for eligible households — typically those on means-tested benefits or with low incomes in poorly insulated homes. Upgrades are provided at no cost to the homeowner.
Common measures funded include loft insulation, cavity wall insulation, solid wall insulation, and boiler replacements. If you're eligible, ECO4 can cover thousands of pounds of work.
Boiler Upgrade Scheme (BUS)
The BUS provides a £7,500 grant toward the cost of an air source heat pump or ground source heat pump, and £5,000 toward a biomass boiler (rural, off-gas-grid properties only). Since late 2025, the scheme also covers air-to-air heat pumps (£2,500) and heat batteries (£2,500). This is available to homeowners in England and Wales replacing fossil fuel heating. It can make heat pumps financially competitive with a new gas boiler — see our boiler grants guide for how to apply.
Warm Homes Plan
The Warm Homes Plan provides funding for energy efficiency improvements in low-income households and fuel-poor homes. It covers insulation, heating, and ventilation improvements. Funding amounts and eligibility criteria are set by local authorities and delivery partners.
Great British Insulation Scheme (GBIS) — now closed
GBIS targeted homes in the least efficient EPC bands (D to G) and provided single insulation measures — often cavity wall or loft insulation — at no cost or heavily subsidised. Applications closed on 31 January 2026, and the scheme ends on 31 March 2026. If you applied before the deadline, your installation may still be completed. For future support, the Warm Homes: Local Grant (from spring 2026) is expected to provide similar insulation funding for eligible households.
How to prioritise your improvements
With so many options, it can be hard to know where to start. Here's a practical approach:
1. Check your EPC recommendations first. Every EPC certificate includes a list of recommended improvements with estimated costs and ratings impact. Look up your property and use the recommendations as your starting point. You can also browse properties in your area to see what improvements are common locally.
2. Start with the cheapest, highest-impact measures. The table above shows that low-cost improvements like loft insulation top-up, heating controls, and LED lighting often deliver the best return in SAP points per pound spent. Do these first.
3. Focus on the fabric first. Insulation (loft, walls, floor) reduces how much energy your home needs in the first place. Heating upgrades (boiler, heat pump) are more effective once the fabric is improved, because the heating system has less work to do.
4. Consider the marginal cost. If you're 2 points short of the next band, a £200 upgrade is worth more than if you're 20 points short. Check your current score and the threshold for the next band, then plan accordingly.
5. Don't over-invest for EPC alone. Some improvements (like triple glazing or ground source heat pumps) cost a lot relative to their SAP impact. They may make sense for comfort, bills, or environmental reasons, but they're not the most cost-effective route if your only goal is to improve your EPC rating.
Landlord cost cap: what you need to know
Landlords in England and Wales must ensure their rental properties meet a minimum EPC rating. Under the current regulations, the cost cap for landlord improvements is £10,000 (including VAT). This is the maximum a landlord is expected to spend on energy efficiency upgrades per property.
Key points for landlords:
- Spending from October 2025 counts. Qualifying expenditure on energy improvements from April 2025 onwards counts toward the £10,000 cap.
- If costs exceed the cap, you can register an exemption on the PRS Exemptions Register. This allows you to continue renting the property even if it hasn't reached the target rating.
- Get multiple quotes. Document all costs carefully — you may need to demonstrate your spending if you apply for an exemption.
- Prioritise the highest-impact improvements to reach the target band as efficiently as possible. Cavity wall insulation and loft insulation typically offer the best value for landlords.
- A new EPC is required after improvements to prove the property meets the standard.
For a full breakdown of landlord obligations, costs, and exemptions, see our landlord guide.
Next steps
- Check your current EPC to see your score, band, and recommended improvements.
- Focus on low-cost wins first — LED lighting, draught proofing, heating controls, and loft insulation top-up.
- Check grant eligibility — schemes like ECO4, BUS, and GBIS can cover some or all of the cost. See our grants guide.
- Get installer quotes for any medium or high-cost measures — prices vary significantly between installers and regions.
- Book a new EPC assessment after completing improvements to get your updated rating.
Every property is different, and the most cost-effective improvement plan depends on your starting point. Use the costs and SAP point ranges in this guide as a planning tool, but always check your property's specific EPC recommendations for the most accurate picture.