What Does EPC Rating G Mean? The Worst Rating Explained
If your EPC certificate shows a band G rating, your home is in the bottom 3% of homes in England for energy efficiency. That sounds alarming, and honestly, it is not great. But the silver lining is significant: G-rated homes have the most to gain from improvements, and they qualify for the most grant support.
EPC Rating G means your home has an energy efficiency score of 1 to 20 out of 100. Band G is the worst possible EPC rating. A typical G-rated home costs £3,000 to £4,000 per year to heat. Only around 3% of English homes are rated G. It is illegal to rent out a G-rated property, and these homes are the highest priority for government grant schemes.
EPC band G at a glance
Where does G sit on the EPC scale?
The EPC scale runs from A (most efficient) to G (least efficient). Each band corresponds to a range of SAP scores out of 100:
Source: MHCLG English Housing Survey 2023/24, percentage of English housing stock by EPC band.
Why is your home rated G?
A G rating does not happen because of one problem. It happens because of several problems combining at once. A G-rated home almost always has:
Solid uninsulated walls
Most G-rated homes are pre-1930s with solid brick or stone walls. These lose heat at roughly three times the rate of an insulated cavity wall. Wall insulation is the single biggest improvement available, but for solid walls it means either internal or external wall insulation, which is more expensive than cavity fill.
Single glazing
Original single-glazed windows with poor seals. These lose roughly twice as much heat as double glazing and let in significant draughts. In listed buildings, secondary glazing may be the only option.
No loft insulation
Either no insulation at all in the loft, or a very thin layer from decades ago. Up to 25% of heat loss in an uninsulated home goes through the roof. Loft insulation is one of the cheapest and most effective improvements available.
Old, inefficient heating
Often a non-condensing boiler, back boiler, old storage heaters, or even coal fires. Heating controls are minimal or absent. The heating system itself may be wasting 30-40% of the fuel it burns.
Energy bills: £3,000-4,000+ per year
At Ofgem Q2 2026 rates (electricity 24.67p/kWh, gas 5.74p/kWh), a G-rated home typically costs £3,000 to £4,000 per year to heat. That is roughly double the UK average of £1,641. Many occupants of G-rated homes simply cannot afford to heat them properly, leading to cold, damp conditions.
What does G mean for landlords?
G-rated properties are illegal to rent
Since April 2020, it has been illegal to let a property rated F or G under the Minimum Energy Efficiency Standards (MEES). Landlords must improve the property to at least band E before granting a new tenancy.
Fines for non-compliance can reach £5,000 per property. And from October 2030, the minimum rises to band C. So the G to E journey is the legal minimum now, but G to C is the target you should be planning for.
If you are a landlord with a G-rated property, see our landlord MEES compliance guide for the full legal details and exemption process.
How to improve a G-rated home
The improvement path depends on your goals. There are three realistic targets:
G to E: the legal minimum for landlords
Gaining 19+ points to reach band E (score 39+). Usually achievable with loft insulation, a boiler upgrade, and basic draught-proofing. Cost: £3,000-£8,000, often heavily subsidised by grants.
G to D: a significant improvement
Gaining 35+ points to reach band D (score 55+). Requires wall insulation on top of the basics. Cost: £8,000-£15,000, with significant grant coverage available for the worst-rated homes.
G to C: the 2030 target
Gaining 49+ points to reach band C (score 69+). A full retrofit: wall insulation, loft insulation, double glazing, modern heating system, and controls. Cost: £15,000-£30,000+, but grants can cover a huge chunk of this for G-rated homes.
| Improvement | Typical cost | EPC points | Annual saving |
|---|---|---|---|
| Loft insulation (0 to 270mm) | £400-£800 | 6-10 | £200-£350 |
| Condensing boiler replacement | £2,000-£3,500 | 8-15 | £300-£500 |
| Solid wall insulation (internal) | £5,500-£8,500 | 10-20 | £350-£550 |
| Solid wall insulation (external) | £8,000-£15,000 | 10-20 | £350-£550 |
| Double glazing | £3,000-£7,000 | 4-8 | £100-£200 |
| Heating controls (thermostat + TRVs) | £150-£350 | 2-4 | £75-£120 |
| Draught-proofing | £100-£300 | 1-3 | £60-£100 |
EPC point gains are approximate and vary by property. Sources: Energy Saving Trust, BRE SAP methodology.
Grants for G-rated homes
G-rated homes get the most support
The worse your rating, the more grant funding is available. G-rated homes are the highest priority for every major energy efficiency scheme. If your home is rated G, you are very likely to qualify for significant free or subsidised improvements.
ECO4 / Warm Homes Plan
The main government-backed scheme for the worst-rated homes. Targets properties rated E, F, and G with comprehensive retrofit packages. Can fund wall insulation, loft insulation, heating upgrades, and more. Income-based and flex eligibility routes available.
Great British Insulation Scheme (GBIS)
Free insulation measures for qualifying households. G-rated homes in lower council tax bands can qualify without income checks. Covers cavity wall, loft, floor, and room-in-roof insulation.
Boiler Upgrade Scheme (BUS)
£7,500 towards an air source heat pump. Particularly relevant for G-rated homes where the existing heating system is beyond repair. Best combined with insulation improvements first.
See our full grants guide for eligibility details and how to apply.
Our honest take on EPC band G
There is no sugar-coating it: G is the worst rating on the scale. Your home is losing heat rapidly through every surface, and you are paying far more than you need to on energy bills. In winter, parts of the home are probably uncomfortably cold no matter how high you set the heating.
But here is the thing: a G-rated home has the most to gain from improvements. Every measure you add will make a bigger difference than it would in a better-rated home. Going from G to D or C is transformative. The comfort difference is enormous. The bill savings are hundreds of pounds per year.
And because the government prioritises the worst homes, you are first in line for grants. Many G-rated homeowners end up paying a fraction of the full retrofit cost. Start with our postcode checker to see exactly what is recommended for your property and what grants you could claim.
Check your specific property
Every G-rated home is different. A Georgian townhouse with solid stone walls needs a different approach from a 1920s terrace with solid brick. Your EPC recommendations will list the specific improvements that apply to your property, with indicative costs and estimated savings.
Check your EPC rating and recommendations
Enter your postcode to see your EPC rating, what improvements are recommended, and what grants you could claim. Free, instant, no sign-up.
Other EPC rating guides
Sources
- MHCLG — English Housing Survey 2023/24 (EPC distribution by band)
- BRE — SAP methodology (EPC scoring)
- Energy Saving Trust — Home improvement savings estimates
- Ofgem — Energy price cap Q2 2026 (electricity 24.67p/kWh, gas 5.74p/kWh)