Every Energy Performance Certificate opens with the same picture: a coloured chart running from a dark green A at the top to a red G at the bottom, with two arrows pointing at your property's ratings. It looks simple, and the idea is simple. But the numbers behind the chart decide whether you can legally let a property, how much your tenants pay to heat it, and how far you are from the 2030 EPC C deadline. According to EPCGuide's analysis of 29.2 million EPC records for England and Wales, 55.3% of homes sit below band C. That is roughly 16.2 million homes on the wrong side of the target. This guide explains exactly what the chart shows and what each band means for you.
What is the EPC rating chart?
The EPC rating chart is the coloured bar-graph at the top of every Energy Performance Certificate. It plots your home on a scale from A (most efficient) to G (least efficient), using a numeric SAP score from 1 to 100 underneath each letter.
The letter band and the colour are just a readable summary of that score. Behind the letter sits the real number, the SAP score, which an accredited assessor produces using the RdSAP methodology (Reduced-data Standard Assessment Procedure). Government guidance describes the rating as "a form of energy cost metric, based on the modelled estimated fuel bill of the property." In plain terms: it estimates how much it costs to run the home for heating, hot water, lighting and ventilation, per square metre of floor area, under standard assumptions. It is a cost measure, not a raw energy or carbon measure. That distinction matters, and we come back to it below.
What are the EPC bands and SAP score ranges?
The chart divides the 1 to 100 scale into seven bands. These are the widely cited SAP boundaries used across the register:
| Band | SAP score | Colour | Typical property | Running-cost implication |
|---|---|---|---|---|
| A | 92 to 100 | Dark green | New-build to Passivhaus standard, or fully retrofitted with renewables | Very low bills, often near net-zero heating cost |
| B | 81 to 91 | Green | Modern home with good insulation, efficient heating, some renewables | Low bills |
| C | 69 to 80 | Light green | Well-insulated home, condensing boiler or heat pump, decent glazing | Below-average bills. The 2030 target |
| D | 55 to 68 | Yellow | Typical older home with some upgrades. The most common band | Average bills |
| E | 39 to 54 | Amber | Older, partly insulated home, ageing heating. Current legal minimum to let | Above-average bills |
| F | 21 to 38 | Orange | Poorly insulated, often solid-wall, older heating | High bills. Illegal to let |
| G | 1 to 20 | Red | Little to no insulation, inefficient or no central heating | Very high bills. Illegal to let |
A quick note on the numbers: these boundaries are the standard ranges used across the EPC register and by assessors, but the underlying SAP methodology is set by government and administered by BRE. Always treat the exact figure on a certificate as the authoritative one for a specific property. For any address, you can check the current record on the government's find an energy certificate service.
For context, EPCGuide's data shows the average SAP score across England and Wales is 63, which sits in band D, six points short of the band C threshold of 69. Band D is the single most common rating at 37.8% of all assessed homes.
Why is the EPC chart colour-coded?
The colour scale is a visual shortcut borrowed from appliance energy labels. It runs from dark green at the top through to red at the bottom:
- Dark green (A) to green (B): efficient homes, low running costs
- Light green (C): the sweet spot the 2030 rules are pushing everyone toward
- Yellow (D) to amber (E): average to below-average, the bulk of older UK housing stock
- Orange (F) to red (G): the worst performers, and unlawful to let privately
The colour tells a tenant or buyer, at a glance, roughly what they are walking into. A red or orange chart is a warning sign of cold rooms and high bills. A green chart signals a warm, cheap-to-run home. For landlords, the colour is also a compliance flag: anything in the orange or red zone cannot legally be let, and anything in yellow or amber has work to do before 2030.
What do the two arrows on an EPC mean?
Look at a real certificate and you will see two arrows on the chart, not one. This trips people up constantly.
- The "current" arrow shows the property's rating as it stands today, based on the assessor's inspection.
- The "potential" arrow shows the rating the property could reach if the recommended improvements were carried out.
So a home might show a current rating of D 58 and a potential rating of C 74. The gap between the two arrows is your roadmap. The certificate lists the specific measures behind that potential score, usually things like loft insulation top-up, cavity wall insulation, a heating upgrade, or better controls, along with indicative costs and savings.
For landlords, the potential arrow is the most useful part of the whole document. If your current rating is below C but your potential rating is C or above, the certificate is effectively telling you which upgrades will get you compliant, and roughly what they cost. You can pressure-test those numbers before you spend anything using the EPCGuide EPC predictor tool.
What does each band mean for a landlord?
Two bands on the chart carry legal weight for private landlords in England and Wales.
Band E is the current legal minimum. Under the Minimum Energy Efficiency Standards (MEES), it has been unlawful to let a property rated F or G since 1 April 2023. Letting below E can attract a penalty of up to £5,000 per property. If your chart shows an orange or red arrow, you are almost certainly non-compliant right now unless you hold a valid registered exemption. See our guide to EPC exemptions for landlords for the routes available.
Band C is the 2030 target. All privately rented homes must reach band C (a SAP score of 69 or above) by 1 October 2030, with penalties rising to up to £30,000 per property. A yellow (D) or amber (E) arrow means you have a plan to make between now and then. Our complete guide to the EPC C deadline walks through the timeline, exemptions and cost cap in detail.
If your chart shows:
- A or B: you are comfortably compliant and future-proofed.
- C: you meet the 2030 target already. No action needed on that front.
- D or E: you can let today, but you have upgrades to plan before October 2030.
- F or G: you cannot legally let the property now without an exemption. This is urgent.
How do you move up the EPC chart?
Moving up a band means adding SAP points, and points come from reducing the modelled running cost of the home. The measures that shift the arrow furthest, roughly in order of cost-effectiveness, are:
- Loft insulation top-up to 270mm. Cheap, and often several points.
- Cavity wall insulation where you have unfilled cavities. Strong value.
- Heating controls, such as a programmer, room thermostat and thermostatic radiator valves.
- A more efficient heating system, for example replacing an old boiler with a condensing model, or moving to a heat pump.
- Draught-proofing and hot water cylinder insulation. Low cost, small but real gains.
- Solar PV panels, which lower modelled cost and can add meaningful points, though at higher upfront cost.
- Solid wall insulation for homes with no cavity. Expensive, but sometimes the only route to C for older stock.
The exact points each measure adds depend on the property, because SAP scores cost per square metre. That is why two identical-looking terraces can sit in different bands: floor area, wall construction, heating fuel and existing insulation all feed the calculation. For a ranked breakdown by cost per SAP point, see our cheapest ways to improve your EPC rating, and for full pricing use the EPCGuide cost calculator. Our complete guide to EPC improvement costs covers every measure by price.
One important caveat: the SAP methodology behind the chart is expected to change. The Home Energy Model is set to replace RdSAP for EPC assessments around 2029, which may adjust how measures score. We track what that means in our guide to the Home Energy Model.
Frequently asked questions
What is a good EPC rating?
Band C or above is considered good and meets the 2030 target for privately rented homes. Bands A and B are excellent and typical of modern or fully retrofitted homes. Band D is average for the UK, and bands E, F and G indicate a home that is expensive to run and, in the case of F and G, unlawful to let.
What is the average EPC rating in the UK?
The average SAP score across England and Wales is 63, which falls in band D. EPCGuide's analysis of 29.2 million records shows band D is the most common rating at 37.8% of homes, and 55.3% of all homes sit below band C.
What SAP score is band C?
Band C covers SAP scores of 69 to 80. A score of 69 is the exact threshold a privately rented home must reach by 1 October 2030. Anything from 69 upward counts as band C or better.
Why are there two arrows on my EPC chart?
One arrow shows your property's current rating, and the other shows its potential rating if the recommended improvements were carried out. The gap between them is your upgrade roadmap, and the certificate lists the measures needed to close it.
What do the EPC chart colours mean?
The colours run from dark green (band A, most efficient) through green, light green, yellow and amber to orange and red (band G, least efficient). Green means low running costs, red means high running costs. Orange and red bands cannot legally be let privately.
Is the EPC rating based on energy cost or carbon?
The main energy efficiency rating shown on the chart is a cost-based metric. Government guidance describes it as a form of energy cost measure based on the modelled fuel bill of the property, per square metre of floor area. There is a separate environmental impact (carbon) rating on the certificate, but the A to G chart most people refer to is the cost-based one.
What EPC band do I need to legally let a property?
Currently you need at least band E to let a privately rented property in England and Wales. From 1 October 2030, the minimum rises to band C. Letting below the required band without a valid registered exemption can lead to penalties.
How do I check my property's EPC rating?
Search the free government find an energy certificate service by postcode, or use the EPCGuide EPC predictor to estimate a rating before paying for a full assessment. If your property has been assessed in the last 10 years, a valid certificate should already be on the register.
This article is a general explainer and last updated on 19 July 2026. EPCGuide's analysis covers the full domestic EPC register for England and Wales (29.2 million records). For methodology and interactive data, visit the EPCGuide Research Hub.
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