An Energy Performance Certificate (EPC) shows how energy efficient your home is, what it costs to run, and where improvements can cut bills. Our 2026 guide explains what an EPC rating means, when you need one, and how upgrades like loft insulation or a conversion can boost your score and property value.
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An EPC rating is short for Energy Performance Certificate rating. It is a legal document that shows how energy efficient your property is, how much energy it uses, and where improvements can be made. Every home sold or rented in the UK must have a valid EPC.
The rating works like a nutritional label for your home. Just as food packaging shows calories and fat content, an EPC shows how costly your home is to heat and how much CO₂ it produces.
The certificate uses a colour-coded scale from A to G:
Most homes currently sit around a D rating, meaning there is significant room for improvement. On this page:
EPC ratings indicate how energy-efficient a home is. The scale runs from A (most efficient) to G (least efficient) and is based on the property’s SAP score, which measures energy performance, insulation, heating efficiency and carbon output.
Understanding these bands helps you see how much energy your home uses, how much it may cost to run and what improvements could raise your score.
EPC Rating C is a score between 69 and 80 SAP points. It indicates a home that is more energy efficient than the UK average and meets the standard that many lenders, landlords and government initiatives now encourage. Homes rated C typically have good insulation, modern heating, double glazing and reasonable energy bills. Achieving an EPC C rating can make a property more attractive to buyers, increase mortgage options, and reduce long-term running costs.
An EPC Rating of F (21–38 SAP points) indicates a home has poor energy efficiency, often due to outdated heating systems, little or no insulation, and significant heat loss. Properties in Band F are expensive to heat and may be uncomfortable in winter.
For landlords, EPC F is critical because renting out a property with an F or G rating is restricted under the current Minimum Energy Efficiency Standards (MEES). Improving an F-rated home often requires upgrades such as loft insulation, wall insulation, or a more efficient boiler.
Generally, EPC Band C or higher is considered a good rating. It reflects a home that is energy-efficient, comfortable to live in, and cost-effective to heat. Many new homes achieve B or A ratings, while many older homes sit in Band D.
Raising a home from D or E to C can significantly reduce energy bills and improve resale value. For homeowners and buyers, Band C has become the benchmark for a modern, efficient property.
An EPC rating is based on a Standard Assessment Procedure (SAP) score, which measures how energy efficient your home is. The higher the score, the better the rating.
During the assessment, several parts of your property are checked, including:
A better EPC score means lower bills, a smaller carbon footprint, and often a higher property value. It also ensures you comply with rental laws, as properties in the private sector must meet minimum efficiency standards.
EPC ratings are calculated using the Standard Assessment Procedure (SAP), the UK Government’s official method for measuring the energy performance of homes. SAP is a modelled calculation that estimates how much energy a property is expected to use for heating, hot water, lighting and ventilation.
It is not based on your personal energy bills or how you use the home, but on how the property is built and the efficiency of its systems.
During an EPC assessment, a qualified assessor records the key features that affect energy performance. This includes insulation levels in the loft, walls, and floors; the type and age of the heating system; boiler efficiency; window glazing; draught-proofing; ventilation; lighting; and any renewable technologies, such as solar panels. They also measure the home's size and layout to identify areas of heat loss.
All of this information is entered into SAP software, which runs a standardised calculation to produce two scores: the SAP rating (a numerical score from 1 to 100+) and the EPC band (A to G). Because SAP uses fixed assumptions about occupancy and energy use, it provides a consistent measure of a home's efficiency, regardless of lifestyle or individual behaviour.
This allows buyers, owners, and landlords to compare homes fairly and highlights which upgrades would improve the property’s overall efficiency.
An EPC is more than just a letter grade. It provides a clear picture of your home’s energy performance today, the cost of running it, and how you can improve it.
Your EPC will show:
Having an up-to-date EPC ensures compliance with the law and can help make your property more attractive to buyers or tenants.
An EPC is a legal requirement in several situations. If you’re planning to sell, rent, or build, you’ll need a valid certificate in place. Having an up-to-date EPC ensures compliance with the law and can help make your property more attractive to buyers or tenants.
Here is when you need an EPC rating:
Checking your EPC rating is quick and free. All valid certificates are stored on official registers, allowing you to look up yours online in just a few minutes.
If your certificate has expired, or if no EPC exists for your property, you’ll need to arrange a new assessment.
You’ll need a new EPC if your current certificate has expired, if your home has never had one, or if you’ve made improvements that could change your rating.
During an EPC assessment, a qualified assessor will visit your property for around 45–60 minutes. They’ll look at the structure of your home, check insulation levels in the loft and walls, assess your heating system, glazing, lighting, and note any renewable technology in place.
All of this information is then entered into government-approved software, which calculates and issues your official EPC rating.
The cost of an EPC in 2025 depends on your property size and location, but most homeowners pay between £60 and £120.
A loft conversion doesn’t just add space; it can also improve your home’s EPC rating. Because the process involves updating loft insulation, glazing, and heating, most conversions leave your property more energy efficient than before.
Here is how your loft conversion will affect potential EPC ratings:
Upgrades made during a conversion are assessed as part of the EPC, meaning your home is measured against today’s standards rather than those in place when the house was built. As a result, a conversion can take a property from a D to a C rating, improving both comfort and value.
Because a loft conversion changes the structure and energy use of your home, you’ll usually need a new EPC once the work is complete. This ensures your certificate reflects the property’s new performance.
If your loft requires additional insulation as part of the conversion, you may be eligible for assistance with the cost. The government-backed Loft Insulation Grants can cover part or all of the upgrade, depending on your eligibility.
Behind every EPC rating is a SAP score (Standard Assessment Procedure), which runs from 1 to over 100. The higher the score, the more energy efficient your home.
Not every property in the UK needs an EPC. The law makes a few exemptions for specific types of buildings.
If you’re unsure whether your property qualifies for an exemption, it’s best to confirm with your local authority or through the official EPC register.
Improving your EPC rating often starts in the loft. Heat rises, so the roof is one of the main areas where homes lose energy. Upgrading insulation, ventilation and the overall thermal performance of your loft can make a noticeable difference to your EPC score.
Loft insulation has one of the biggest impacts on EPC performance. Adding mineral wool, rigid boards, or spray foam (approved types only) reduces heat loss through the roof. The recommended depth for mineral wool insulation is 270mm, which can help move a home from Band D/E into Band C by lowering heating demand.
Converted lofts lose heat through sloping ceilings, dormer walls and the roof structure itself. Upgrading insulation to meet or exceed modern building regulations, especially with rigid PIR boards or enhanced multi-layer systems, reduces energy loss and can noticeably improve your EPC score.
Dormer sides and flat roof sections are common cold spots. Adding high-performance insulation here reduces drafts, heat loss and cold bridging. This upgrade improves comfort and energy ratings.
Older roof windows can leak heat. Replacing them with modern double- or triple-glazed units improves thermal efficiency and reduces your home's overall heat demand. Roof windows with low U-values improve the EPC calculation.
Even if part of your loft is converted, unconverted areas can still impact EPC ratings. Topping up floor insulation in storage zones or cold voids helps prevent heat from escaping into unused roof space.
Small gaps around the loft hatch, eaves and window frames allow warm air to escape. Draught-proofing these areas and installing a well-sealed, insulated loft hatch can improve airtightness, which is measured in the EPC assessment.
Lighting contributes to the final EPC score. Replacing halogen or older bulbs with LED lighting in loft rooms, landings and storage spaces offers a small but measurable improvement.
Although not technically a loft upgrade, installing solar panels on the roof of your loft conversion has a significant positive impact on EPC ratings. They reduce carbon emissions and offset electricity costs, often lifting a property into a higher EPC band.
Still unsure about EPC ratings? Here are answers to some of the most frequently asked questions by homeowners.
An EPC rating is based on a SAP score (Standard Assessment Procedure). It measures how energy-efficient your home is by examining insulation, heating, lighting, glazing, and any renewable energy sources. The score is then placed on a colour-coded A-G scale, with A being the most efficient and G the least.
Yes. A loft conversion changes the structure and energy use of your home. Adding insulation, double glazing, and modern heating usually improves your EPC score. You will need a new EPC after the conversion is complete.
An EPC is valid for 10 years. You can choose to get a new one sooner if you make upgrades that would improve your rating.
In 2025, the cost of an EPC is typically £60 to £120, depending on property size and location. Flats are at the lower end of the range, while larger detached homes are more expensive.
No. By law, you must have a valid EPC before putting your property on the market. Buyers need to see it as part of the sales process.
