EPC rating (Energy Performance Certificate)

What is an EPC rating?

An EPC (Energy Performance Certificate) rating tells you how energy efficient a property is. This gives you a good idea of what the energy costs for that property would be. The EPC rating goes from A (very efficient; low running costs) to G (very inefficient; high running costs).

This gives you a good idea of how much the energy cost for that property would be. The EPC rating goes from A (very efficient; low running costs) to G (very inefficient; high running costs).

EPC ratings work a lot like exam grades. An EPC assessor looks at how energy efficient different parts of your home are. This includes your heating system, your walls, and even your light bulbs.

The EPC assessor then calculates a score out of 100. This is known as the Standard Assessment Procedure (SAP) score. Using the SAP score, the assessor works out the EPC rating.

You’ll find your home’s EPC rating on its Energy Performance Certificate (EPC).

How is an EPC rating worked out?

There are two methods for working out a home’s energy performance:

• The Standard Assessment Procedure (SAP)
• The reduced data Standard Assessment Procedure (rdSAP)

SAP and rdSAP scores

Both these methods involve a specialist assessing your home, then making calculations to come up with a score. The major difference between them is the amount of information that the assessor can access.

With the SAP, the assessor looks at architectural plans and other construction documents.

On the other hand, with an rdSAP, the assessor doesn’t have access to these documents. Instead, they visit the property and make calculation based on what they can see.

The SAP method is used for new dwellings, whereas the rdSAP method is used for existing dwellings.

You can find out more in-depth information about SAP and rdSAP on the gov.uk website.

What are the different EPC ratings? 

An assessor will work out a SAP or rdSAP score for your property. The score will be out of 100, with 100 being the most energy efficient. The SAP/rdSAP score will determine the EPC rating.

What is energy efficiency? 

Our Energy Performance Certificate rating tells us how energy efficient our homes are, but what does energy efficiency actually mean? 

At its simplest, energy efficiency means getting the result we want by using as little energy as possible.   

Let’s take heating our home as an example. The result we want is a warm home. An energy efficient system would be one where we can get a warm home using as little energy as possible.  

A good example of an inefficient system would be a wall that doesn’t have any insulation. We use energy to run our heating. Without insulation, a lot of that heat is lost through the wall. This means we have to use more energy to replace the lost heat. 

A good example of an efficient system would be an air source heat pump. You don’t need to put much electricity into a heat pump to get a lot of heat out. Every kilowatt (kW) of electricity you put in gives you 3kW of heat.   

How to improve your EPC rating 

Improving your EPC rating means making changes to your home’s insulation and/or heating system. What changes you make depend on what you already have in place.

For example:  

• You may already have loft insulation but no wall insulation 
• You may have a gas boiler, but it may be old and inefficient    

If you already have an Energy Performance Certificate, it will tell you how to improve your rating. You’ll find a ‘Recommendations for Improvement’ section on page two. Your EPC lists the improvements in order of importance. The ones at the top of the list will make the biggest difference to your rating. 

The ‘Recommendations for Improvement’ section also tells you what rating you’ll reach by making the suggested changes:

In this example, installing internal or external wall insulation will raise the rating to C77.

If you don’t already have an Energy Performance Certificate, you can find out how to improve your EPC rating by: 

• Speaking to Home Energy Scotland. Their advisors will help you work out what changes will make your home more energy efficient. You can call them for free on 0808 808 2282. You can also contact them through their online form. 
• Getting an EPC. See the How to get an energy performance certificate section below.