What the EPC recommendations cost to do
The short answer
- £200 to £12,000: from low energy lighting to internal solid wall insulation
- £105 a year measured saving from cavity wall insulation in a 3 bed semi, for about £2,200
- £5,200 for a heat pump after the £7,500 grant, saving about £172 a year on a heat pump tariff
- No sourced saving for heating controls, a new boiler or low energy lighting, so we do not give one
The recommendations on an EPC run from about £200 for low energy lighting to £12,000 or more for solid wall insulation. This guide gives the cost of each, the yearly saving and the payback for a typical 3 bed semi on gas, and says plainly where no sourced saving exists.
Every EPC recommendation, costed
From £200 for lighting to £15,000 for external wall insulation. Measured savings exist for insulation; the table says where no sourced saving exists.
| Recommendation | Typical cost | Saving a year, 3 bed semi on gas | Payback | EPC points, our model |
|---|---|---|---|---|
| Loft insulation, from under 100mm to 270mm | £750 | £28 | about 27 years | +7 |
| Loft insulation top-up to 270mm | £600 | £28 | about 21 years | None from 100mm in our model |
| Cavity wall insulation | £2,200 | £105 | about 21 years | +8 |
| Solid wall insulation, internal | £12,000 | £151 | over 50 years | +10 |
| Solid wall insulation, external | £15,000 | £151 | over 50 years | +10 |
| Suspended timber floor insulation | £1,400 to £2,500 | £55, modelled | about 25 to 45 years | Not in our model |
| Heating controls | £275 | No sourced figure | Not known | +3 |
| New condensing gas boiler | £3,500 | No sourced figure | Not known | Up to +8 |
| Air source heat pump | £5,200 after the £7,500 grant | £172 on a heat pump tariff | about 30 years | Up to +12 |
| Solar panels, 4 kW | £6,000 | £556 in southern England | 10.8 years | +8 |
| Double glazing, replacing single | £4,800 | £85, modelled | over 50 years | +6 |
| Low energy lighting throughout | £200 | No sourced figure | Not known | Up to +3 |
Read the detail
The cheapest recommendations on a certificate are low energy lighting at about £200 and heating controls at about £275; the dearest is solid wall insulation at £12,000 to £15,000. Where a saving has been measured or modelled from a named source, the table gives it with the payback; where we have no sourced saving, it says so.
Savings are for a 3 bed semi-detached house with average insulation heated by mains gas, at the Ofgem price cap for October to December 2026, energy only. Loft, cavity and solid wall savings are the median fall in gas use the government measured in real homes after each measure. Floor and glazing savings are the Energy Saving Trust's modelled estimates. Solar is the yearly saving and export income for a south facing roof from our solar calculator. Points are from our EPC calculator's simple model, not the assessor's software.
The recommendations on a real certificate are worked out for that home, so check its list against this one. Our home buyer energy check picks the cheapest of them to reach band C for a particular home, and the retrofit plan puts the insulation and heating work in order for the home after you move in.
Insulation: loft, cavity, solid wall and floor
Cavity walls save the most for the money: about £105 a year for a semi on gas, for about £2,200. Loft insulation costs about £750 and saves about £28.
| Home | Loft, under 100mm to 270mm | Loft top-up to 270mm | Cavity wall |
|---|---|---|---|
| Detached house | £1,100 | £800 | £3,900 |
| Semi-detached house | £750 | £600 | £2,200 |
| Mid-terrace house | £650 | £500 | £1,100 |
| Detached bungalow | £1,200 | £800 | £1,700 |
Read the detail
Cavity wall insulation gives the biggest measured saving for its cost: about £105 a year for a 3 bed semi on gas, for about £2,200. Loft insulation is cheap at about £750 but its measured saving is small, about £28 a year.
Energy Saving Trust figures for a typical professional installation in Great Britain, before any grant. Floor insulation for a suspended timber floor costs £1,400 to £2,500 depending on the house; the Trust does not split it by home.
The savings come from the government's measurements of real homes before and after each measure: a median 12% less gas after cavity wall insulation across 2,191 homes, 17% after solid wall insulation across 2,411, and 3.2% after loft insulation across 1,486. The loft figure mixes top-ups with bare lofts, so a loft with nothing in it usually saves more. Measured savings run lower than the modelled figures most tools quote, partly because many homes were cold before and some of the gain is taken as warmth.
Floors have not been measured this way. The Energy Saving Trust models about £55 a year for a semi, so at full price a floor takes decades to pay back. Our guides to cavity wall insulation, solid wall insulation and underfloor insulation go further.
Heating: controls, boiler and heat pump
A heat pump costs £5,200 after the grant for a 3 bed semi and saves about £172 a year on a heat pump tariff. Controls and a new boiler have no sourced saving.
| Home | New condensing gas boiler, installed |
|---|---|
| 1 bedroom | £2,950 |
| 2 bedrooms | £3,200 |
| 3 bedrooms | £3,500 |
| 4 bedrooms | £3,800 |
| 5 bedrooms or more | £4,050 |
Read the detail
A heat pump for a 3 bed semi costs a median £12,700 installed, or £5,200 after the £7,500 Boiler Upgrade Scheme grant, and saves about £172 a year against gas on a heat pump tariff. We have no sourced figure for what a new boiler or new controls save.
The 3 bed figure is the DESNZ average for a new condensing gas boiler including VAT; other sizes are scaled from it by our model, which is our assumption.
The heat pump figures are for a 9 kW air source heat pump at the median price installers recorded under the Boiler Upgrade Scheme, running at the median efficiency measured in the government's Electrification of Heat trial. The grant is £9,000 where the heat pump replaces oil or LPG. On a standard electricity tariff the saving is much smaller, which is why the tariff matters: see heat pump tariffs and the heat pump calculator.
A certificate often recommends a new boiler or better controls where the boiler is old. Both lift the EPC score in our model, but we have found no measured or sourced figure for the bill saving, so we do not give one rather than guess. A new boiler is usually bought because the old one is failing, and the choice between a boiler and a heat pump is laid out in heat pump vs new boiler.
Solar panels, windows and lighting
Solar pays back in 10.8 years in southern England. Double glazing costs about £4,800 for a semi and saves about £85 a year, so it is bought for comfort.
Read the detail
A 4 kW solar system costs about £6,000 and earns about £556 a year on a south facing roof in southern England, paying back in 10.8 years; in Scotland it is 12.6 years. Replacing single glazing costs about £4,800 for a semi and saves about £85 a year.
The solar figures come from our solar calculator for a household out for about half the day, counting both the electricity used at home and export payments. Our solar payback guide covers other roofs and regions.
The glazing figures are the Energy Saving Trust's for A-rated double glazing in a semi-detached house. At over 50 years the payback is long, so new windows are usually bought for comfort, noise and condition rather than the bill. In a conservation area, secondary glazing can be the option the council accepts.
Low energy lighting costs about £200 for a whole house in our EPC model and adds a few points cheaply. We have no sourced figure for its bill saving, and it only matters where the house still has older bulbs.
Where we have no sourced saving
Heating controls, a new boiler and low energy lighting. Rather than invent a saving, we leave it out; the certificate's own report gives an indicative figure for that home.
Read the detail
Three common recommendations have no sourced saving on this site: heating controls, a new gas boiler and low energy lighting. Floor insulation and double glazing have modelled savings only, from the Energy Saving Trust.
We use measured savings wherever the government has measured them, which it has for loft, cavity wall and solid wall insulation. For the rest we would have to make a figure up, and a payback built on a made-up saving is worse than none. If you are weighing one of these, the assessor's own recommendations report on the certificate gives an indicative saving for that home, worked out by the official software.
Which to do first after you move in
Insulation first, cheapest payback first, then the heating. A heat pump sized for the insulated home is smaller and cheaper.
Read the detail
Insulation first, cheapest payback first, then the heating. For a 3 bed semi on gas that means cavity walls if they are unfilled, about about 21 years to pay back, then the loft, then a heat pump sized for the insulated home.
Doing the fabric first means the heat pump can be smaller, and a smaller heat pump costs less. The retrofit plan works through this order for your home, with the cost, saving and payback of each step, and the EPC calculator ranks the same measures by points per pound if the band is what you need. Grants can change the order: ECO4 can fund insulation for households on qualifying benefits until 31 December 2026, and insulation, solar panels and heat pumps carry 0% VAT until 31 March 2027. Check what you qualify for with the grant checker.
Frequently asked questions
What do EPC recommendations cost?
From about £200 for low energy lighting and £275 for heating controls to £12,000 for internal solid wall insulation. Cavity wall insulation costs about £2,200 for a semi-detached house and loft insulation about £750.
Which EPC recommendation pays back fastest?
Cavity wall insulation, among those with a measured saving: about £2,200 for a semi, saving about £105 a year on gas, about 21 years. Solar panels on a south facing roof in southern England pay back in 10.8 years.
Do I have to carry out the recommendations on an EPC?
No. If you are buying to live in the home, the recommendations are advice, not requirements. Landlords are different: privately rented homes must reach band E now and a band C equivalent standard from 1 October 2030.
Are the costs on the certificate accurate?
They are indicative ranges produced by the assessor's software, and they can be several years old. Check the date on the certificate and compare with current figures such as those on this page.
What does a heat pump save?
About £172 a year against gas for a 3 bed semi with average insulation on a heat pump tariff, after a median £12,700 installed and the £7,500 grant. On a standard tariff it saves much less.
Data sources
Energy Saving Trust costs and government measured savings, with heat pump costs from the Boiler Upgrade Scheme statistics.
Show every source
- Energy Saving Trust advice pages, 2026: cavity wall, loft, solid wall and floor insulation costs; the floor and glazing savings.
- Department for Energy Security and Net Zero, NEED impact of measures data tables 2026: measured savings after loft, cavity and solid wall insulation.
- Department for Energy Security and Net Zero, Boiler Upgrade Scheme statistics, August 2026: heat pump installed costs.
- Energy Systems Catapult for DESNZ, Electrification of Heat trial, December 2024: heat pump efficiency. Ofgem price cap for October to December 2026.
- Our solar calculator (PVGIS generation, MCS self-consumption tables) and EPC points model.