The cheapest ways to improve an EPC rating
Ask ten people how to improve an EPC and you'll hear about new windows. They're one of the worst value options on the list.
An EPC score is driven by the home's modelled running costs. The upgrades that cut those costs most cheaply are the ones that move the score most cheaply. That's rarely the most visible work.
Cost per point, roughly
The table below uses a semi-detached house rated D61 as an example. Costs are typical installed prices from Energy Saving Trust figures where available. Points are typical, and the real result depends on the property.
| Upgrade | Typical cost | Typical points | Cost per point |
|---|---|---|---|
| Hot water tank jacket | £30 to £80 | +1 | Under £100 |
| LED bulbs throughout | £40 to £120 | +1 | Under £150 |
| Loft insulation, bare to 270mm | £825 to £930 | +8 | About £110 |
| Cavity wall insulation | About £2,700 | +7 | About £390 |
| New condensing boiler (from an old one) | £3,000 to £4,200 | +7 | About £500 |
| Solar panels, about 3.5kWp | £5,500 to £7,000 | +9 | About £700 |
| Internal solid wall insulation | About £12,000 | +9 | About £1,300 |
| Single to double glazing | About £7,500 | +3 | Over £2,000 |
Sources for the costs are listed on the methodology page. The points are estimates for this example home.
Start with the loft and walls
If a loft has little or no insulation, topping it up to 270mm is usually the best value upgrade there is. Cavity wall insulation is often next. Together they can add 10 to 15 points to a home that hasn't had them.
Check first. Many homes built between the 1920s and 1990s had their cavities filled under past schemes. A row of small filled holes in the mortar is the usual giveaway. Your EPC's features section also says whether the walls are insulated.
Small jobs add up
A tank jacket, LED bulbs and proper heating controls each add only a point or two. But they're cheap, and a home that's two or three points short of C may need nothing more.
Heating matters as much as insulation
An old non-condensing boiler, or old storage heaters, can drag a score down badly. Replacing them often adds more points than any single insulation job. For homes with plug-in or panel electric heaters, switching to modern storage heaters on an off-peak tariff can add 15 points or more.
Expensive jobs come last
Solid wall insulation and new windows make homes more comfortable, but they're costly for the points they add. For EPC purposes, they're usually the final step, and only if the cheaper measures don't get you there. If they push the total over the £10,000 cap, an exemption may be the right answer instead.
Grants can change the order
Some upgrades can be partly or fully funded, depending on the tenant's circumstances and where the property is. Grant funding generally counts towards the £10,000 cap, so check what's available before paying for anything yourself.
Check your own rental
The free checker estimates where your property stands against EPC C and the cheapest likely route to get there, with sourced costs.