Which? published research on 18 July 2024 finding that most Energy Performance Certificates (EPCs) in its sample did not appear accurate, and called on the government to reform the certificates, review EPC auditing and review the training requirements for Domestic Energy Assessors1.
The consumer body selected 12 homeowners across England, Wales and Scotland and booked EPC assessments during February and March 2024. The properties ranged from a one-bedroom flat to a five-bedroom detached house and were built between 1650 and 19991. One participant was surveyed but never received a certificate; the fee was later refunded. Of the remaining 11, just one was "very satisfied" with their EPC and only three said they were likely to recommend getting one based on the experience1.
Eight of the 11 said their EPC did not appear accurate, citing incorrect descriptions of key aspects of their home such as windows, roofs and heating systems1. In one case, errors were pointed out to the assessor, corrected, and a new EPC issued with the rating moving up two bands, from D to B1. On recommendations, one EPC proposed changes that could save £920 a year on energy bills, but the total estimated cost meant it could take up to 29 years to break even on the outlay1. Solid wall insulation was recommended at a cost of £4,000 to £14,000 for both a two-bedroom mid-terrace and a four-bedroom detached house1.
Most of the EPCs in the study were produced by assessors registered with Elmhurst Energy, the largest accreditation scheme, with around 7,500 Domestic Energy Assessor members1. After Which? shared its results, Elmhurst audited four of the EPCs. One was correct; three of the four were found to be inaccurate. Two have been or will be re-lodged to correct the errors, and the third property requires another visit for reassessment before an updated EPC can be produced1. Elmhurst confirmed it is unlikely that any of the three inaccurate EPCs would have been caught by the standard auditing process1.
"We’re calling for the government to reform these certificates to make them a more reliable and useful tool for householders."
Which? said the government should review the auditing of EPCs and the training requirements for Domestic Energy Assessors, and that EPCs should include clear, actionable advice for consumers, including low-cost measures as well as more expensive options1. Elmhurst managing director Stuart Fairlie said the scheme continues to champion reform of the wider EPC system including quality training standards, adding that this has been on the agenda since the government's 2020 EPC Action Plan and that it is "imperative for the next government to quickly deliver"1.
Why it matters for households
An EPC gives a home a rating between A (very efficient) and G (inefficient), and a valid certificate is still needed when selling or letting a home1. The ratings now feed into government policies aimed at decarbonising homes, a wider use than the certificates were designed for1. For a household, an inaccurate certificate can mean recommended building work that is costly and unnecessary, while a corrected, better rating can affect a home's value and its appeal to buyers or tenants1. The findings also bear on grant eligibility and other schemes that use EPC bands as a qualifying test, since a wrong band can change what a home is offered. The EPC regulations and reform framework sets the rules the certificates are issued under, and DESNZ is the department responsible for home energy policy in Great Britain. Where a certificate is wrong, there is a route to challenge it, set out in who to contact about an EPC problem, and the certificate itself can be read in detail using the guidance on how to read an EPC.
What happens next
Two of the four audited EPCs have been or will be re-lodged to correct errors, and the third property requires another visit for reassessment before an updated EPC can be produced1. Which? has called for a government review of EPC auditing and assessor training requirements, and for clearer advice within certificates1. No government response or timetable for reform has been reported.