In the UK, Energy Performance Certificates (EPCs) are an essential part of buying, selling and renting homes. But what is an EPC rating? In this article, we explore what an EPC rating does, before explaining each part of the Energy Performance Certificate step by step.

What is an EPC rating?

In short, an EPC rating is a review of a property’s energy efficiency. They’re primarily used by would-be buyers or renters to quickly see how much their energy bills will cost in their new house or flat.

In England, Wales and Northern Ireland, EPCs are carried out by EPC assessors or ‘Domestic Energy Assessors’ (in Scotland, they must be government-approved organisations). The EPC assessor will carry out a brief survey of your home before producing the EPC. The house is then placed on a colour-coded scale from A to G, A being the most efficient with the cheapest fuel bills.

Your house’s EPC rating will depend on:

  • The amount of energy used per m²
  • The level of carbon dioxide emissions (given in tonnes per year)

Once issued, the EPC will be valid for 10 years – if your EPC is older than this, you’ll need to get a new EPC issued before you can sell or rent your house.

Anyone can access a house’s EPC online for free via the EPC register, so they come in handy when comparing potential future homes on paper. It’s the responsibility of the house seller or landlord to provide a valid EPC – the prospective buyers shouldn’t have to pay anything.

But there’s a bit more to it than that. EPCs are also a useful tool for homeowners to improve the efficiency, running cost and thus the overall comfort of their home.

The importance of a high EPC rating

Apart from listed buildings, every house needs to have a valid EPC before it can be sold. The EPC rating makes for a much easier comparison between houses, particularly when potential buyers are forced to make a tough call between several homes. Even at a glance, almost anyone would opt for the high-scoring, A-rated, green property over the low scoring, G-rated, red one.

If the latter is the case for your home, don’t worry; the Energy Performance Certificate explains what steps can be taken  to improve your EPC rating. So, improving the energy efficiency of your home now will stand you in good stead when it comes to selling.

Once you’ve made the improvements, it’s a good idea to have a new survey done to reflect these changes.

As of April 2018, landlords in England and Wales are required by law to get an EPC rating of band E or above to let their properties to new tenancies or renewals. Additionally, EPCs are essential for claiming from government incentives such as the Renewable Heat Incentive (RHI).

Energy Performance Certificate explained

Once you’ve found the EPC for your current or prospective house (you can find it via the EPC register here), we’ll now talk you through what it all means. The EPC used in this example is of a 3-bedroom new build house.

Estimated energy costs

Energy Performance Certificate explained: estimated energy costs


The first section of the Energy Performance Certificate explains and highlights the house’s estimated cost of energy, which is divided into 3 categories: lighting, heating, and hot water. These figures are based on energy prices at the time the EPC was issued. Since the cost of energy is changing, don’t be surprised if you end up paying more than what was estimated on the EPC. Also, these running costs don’t take extra appliances into account, such as computers and TVs.

Energy efficiency rating

Energy Performance Certificate explained: energy efficiency rating


Next, the all-important EPC rating of the  house is given on the ‘energy efficiency’ scale, just like you see on the back of modern appliances. This scale spans from A to G, A being the most efficient, and G the worst. The higher the efficiency, the lower the running costs.

Alongside the current energy efficiency rating of the house is a ‘potential rating’, which indicates how efficient the house could be if the suggested improvements are installed (there’s more on this later).

Top actions you can take

Energy Performance Certificate explained: top actions


This section is most suited to homeowners looking to do some home improvements. Here the EPC assessor recommends the energy efficiency measures to take, how much they would cost to install, the savings over 3 years, and whether they’re available under the Green Deal initiative. The improvements suggested here are usually the easiest and quickest to implement, but they have a large impact on your EPC rating. Since the example of an EPC is of a new build, most of its energy efficiency measures were covered during installation in order to meet with modern Building Regulations.

Summary of a house’s features

Energy Performance Certificate explained: summary


This section of the Energy Performance Certificate breaks down the various elements of the building, for instance the walls, windows, floors, heating etc, before describing its type and energy efficiency rating.

For elements that are difficult to tell the energy efficiency, the EPC assessor will make an informed estimate. This is usually based on the age of the house. You’ll be able to tell where this is the case because you’ll see “(assumed)” written in that element’s description.

An example of where an EPC assessor will do this is with cavity insulation. It’s difficult to know how energy efficient the walls of your house are without taking a sledgehammer to one of them. EPC assessors would base their calculation on the age of the house, and the requirements of Building Regulations of that time, so remember to keep any documentation of energy efficiency improvements to hand during the EPC survey!

Low and zero carbon energy sources

Energy Performance Certificate explained: low carbon energy sources


As the description suggests, this section of the EPC is about sources of energy that have little or no carbon emissions. These may include biomass boilers, ground source or air source heat pumps.

Your home’s heating demand

Energy Performance Certificate explained: heating demand


The table indicates how much heating will be required (kWh per year) in the form of space heating and hot water. If you’re living in a poorly insulated house (don’t worry, most people in the UK are), the table gives an estimate of how much this heat demand will reduce by adding the recommended measures.

These figures are also used in the calculation for the Renewable Heat Incentive.


Energy Performance Certificate explained: recommendations


Going into more detail from the ‘top actions you can take’, the recommendations explained in this section of the Energy Performance Certificate are cumulative. This effectively serves as a step-by-step guide to take your home’s EPC rating from red to green. Along with estimated costs, the EPC calculates how much could be saved per year, and the effect that measure would have on the overall EPC rating.

You can find out more about this in the article ‘how to improve your EPC rating’.

The environmental impact of buildings

Energy Performance Certificate explained: environmental impact


Lastly, after a short section about the EPC assessor and the certificate, the final paragraph gives a (rather troubling) estimate of how much carbon dioxide is produced by your home. This is followed by the reduced estimate once the aforementioned improvements are put in place.

What we do

Here at Evergreen Energy, we design and supply bespoke renewable energy systems for homes around the UK. These systems bring various renewable energy technologies together in a single integrated heating and electricity solution.

Not only can our renewable energy systems bring eco-friendly energy to your home efficiently and affordably, they also greatly improve your EPC rating and raise the property value. For more information about how we can help you reach the highest EPC rating possible for your property with a renewable energy system install, head over to our what we do page.


  • Hi there

    Can you advice me at all? I am in the process of having my house signed off ATM by Stroma. It is a new build passive house rated building with triple glazing throughout. It is timber framed with 200mm thick insulation around the exterior. The house is vented with an MVHR and has recently had an air test with a good 2.00 rating and highly insulated throughout and I’m putting solar panels in the roof to heat the floor and water during the day; however Stroma are issuing an EPC rating of D! Purely because the heating is electric underfloor heating. I can understand that this is because electricity is generated by coal fired plants but it seems to be a very narrow thing to measure your EPC on they seem to not be taking all the other things into account and it seems the only way I can increase my EPC rating is by having a gas boiler installed. Is there any advice you can give me on increasing my dreadful rating with out putting in gas C/H. Thank you.


    • Hi there Julian,

      I’m sorry to hear about this, ultimately the data calculation is RdSAP (reduced data Standard Assessment Procedure) and the calculation formula is created by British Research Establishment (BRE for short). Stroma is just the software that is used to capture the data that then goes through the BRE-approved formula. The only thing I can suggest is to speak directly with BRE to see what they can do about this to see if they can sort this for you.

      Hope this helps Julian, and best of luck getting to the bottom of this!

You may also like

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.