Which? has called for reform of Energy Performance Certificates after a snapshot investigation found they can be "riddled with inaccuracies and unhelpful advice". The consumer organisation booked EPC assessments on behalf of 12 homeowner members across England, Wales and Scotland between February and March 2024, at properties built between 1650 and 1999 and ranging from a one-bedroom flat to a five-bedroom detached house1.
One homeowner had the survey done but never received a certificate, and the fee was refunded. Of the remaining 11, just one was "very satisfied" and only three said they were likely to recommend getting an EPC on the basis of the experience. Eight of the 11 said their EPC did not appear accurate, citing incorrect descriptions of windows, roofs and heating systems1.
Two cases illustrate the findings. Peter and Carol Vermeulen, in Aberdeenshire, received a D rating for their 1980s four-bedroom semi-detached bungalow. Their solar PV and solar thermal panels and a wood-burning stove were not mentioned, and the suspended floor was described as uninsulated despite underfloor insulation being discussed with the assessor. After Which? raised the errors, the assessor admitted omissions, which he blamed on the software, and issued a corrected EPC with a B rating1.
Megan Dobney received a D rating for her two-bedroom Victorian terraced house in London. The EPC recommended four measures:
| Measure | Typical cost | Stated annual saving |
|---|---|---|
| Internal or external wall insulation | £4,000 to £14,000 | £172 |
| Suspended floor insulation | £800 to £1,200 | £70 |
| Solar water heating | £4,000 to £6,000 | £57 |
| Solar panels | £3,500 to £5,500 | £621 |
Installing all four could cost up to £26,700 and would move the property up one band, from D to C, with savings of around £920 a year, meaning it could take up to 29 years to recover the cost1.
Which? wants the next government to reform EPCs, including their design and content, to cover preparation for the transition to low-carbon heating, make them interactive, include up-to-date costings by property type, and link to financial support and a database of installers in government-certified schemes. It also wants a review of auditing and training requirements for Domestic Energy Assessors1.
"However, our research shows they are in desperate need of reform - with current certificates often inaccurate and only suggesting costly improvements with long pay back periods."
Elmhurst Energy, described as the largest accreditation scheme with over 7,000 DEA members and the scheme most of the EPCs in the study were registered with, said it shared frustrations about the current EPC and had long campaigned for reform. Managing director Stuart Fairlie said the organisation runs a "risk-based" auditing programme and requires re-assessment where defects are found1.
EPCs were introduced in 2007. The UK government published an EPC Action Plan in September 2020 setting out 35 actions, following a call for evidence launched in July 2018; a November 2021 progress report stated that 11 of the 35 had been completed1.
Why it matters for households
EPC ratings are used well beyond comparing properties. Access to grant funding and to green financial products such as loans or mortgages is often available only to those meeting EPC-based criteria, and ratings play a role in government policies aimed at decarbonising homes1. An inaccurate certificate can therefore affect what a household can access, as well as the price a seller can command or how attractive a home is to tenants1.
The cost figures in the research also bear on a home's energy independence: the payback periods quoted for the recommended measures are long, and the certificate for one property rose only one band after all four were installed1. Which? states that EPCs should provide information to help consumers prepare for the transition to low-carbon heating, which the current certificates in its sample did not1.
What happens next
Which? is calling on the next government to reform EPCs, review the auditing of EPCs and the training requirements for Domestic Energy Assessors1. Elmhurst Energy said it is imperative for the next government to quickly deliver reform of the wider EPC system, including quality training standards, an item it says has been on the agenda since the 2020 EPC Action Plan1. No timetable for any reform has been reported.