Understanding Energy Performance Certificates: A Complete Guide
Everything you need to know about EPCs: what they are, when you need one, how they are calculated, and how to read the recommendations report.
By First Certify · 2025-06-01 · 8 min read
First Certify is a UK property compliance platform staffed by accredited assessors and qualified engineers. This article has been reviewed for accuracy against current UK regulations, including MEES, the Electrical Safety Standards 2020, and the Gas Safety (Installation and Use) Regulations 1998.
An Energy Performance Certificate (EPC) is a document that rates a propertys energy efficiency on a scale from A (most efficient) to G (least efficient). It is legally required before a property can be marketed for sale or rent in the UK, and it is valid for 10 years.
The EPC is produced by an accredited domestic energy assessor who visits the property and collects data on its construction, heating system, insulation, windows, and lighting. This data is entered into the RdSAP (Reduced Data Standard Assessment Procedure) software, which calculates the energy efficiency rating and the environmental impact rating.
The certificate has two ratings. The current rating reflects the property as it is today. The potential rating shows what the property could achieve if all recommended improvements were made. The difference between the two tells you how much room there is for improvement.
The recommendations report is the most useful part of the EPC for property owners. It lists suggested improvements, estimated costs, and the potential impact on the rating. Typical recommendations include loft insulation, cavity wall insulation, boiler upgrades, double glazing, and low energy lighting. Each recommendation is classed as low, medium, or high cost.
For landlords, the EPC is tied to MEES compliance. Your property must achieve at least an E rating before you can let it. If the current rating is F or G, the recommendations report shows you what needs to be done to reach E.
For homeowners, the EPC is required before selling but is also a useful tool for understanding your propertys energy performance. The recommendations can guide you towards improvements that reduce running costs and improve comfort.
The assessment takes 30 to 45 minutes and is non invasive. The assessor does not move furniture or open sealed cavities. They photograph key features for evidence and enter the data into the RdSAP software after the visit. The certificate is lodged on the national EPC register, usually within 72 working hours (most within 24–48).
You can check any propertys EPC for free on the official EPC register. Simply enter the postcode and select the property. The register shows the current rating, the issue date, and the expiry date.
FAQs
What is an EPC?
An Energy Performance Certificate rates a propertys energy efficiency from A to G. It is legally required before marketing a property for sale or rent and is valid for 10 years.
How is the EPC rating calculated?
An accredited assessor visits the property and collects data on construction, heating, insulation, windows, and lighting. This is entered into RdSAP software, which calculates the energy efficiency and environmental impact ratings.
What is the difference between current and potential ratings?
The current rating reflects the property as it is today. The potential rating shows what it could achieve if all recommended improvements were made. The difference tells you how much improvement is possible.