An Energy Performance Certificate (EPC) shows how energy efficient your home is, what it costs to run, and where improvements can cut bills. This 2025 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:
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.
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.
An EPC does more than meet a legal requirement. It gives you a clear picture of how your home performs and the steps you can take to make it more efficient.
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.
