Energy performance certificates ‘riddled with inaccuracies,’ homeowners warned

Inaccurate energy performance certificates (EPCs) could mean homeowners are missing out when it comes to selling a property.

EPC ratings can give a boost to house prices by around £13,000 and it has become a  become a key marketing tool when trying to sell a property, especially with high gas and electricity bills.

But new research by Which? has questioned how accurate EPCs ratings are.

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Analysis by the consumer watchdog found that, in some cases, the EPCs recommended unaffordable work or excluded recommendations that could easily boost a home’s rating and essentially the property value.

“With millions of families worried about high energy bills and the UK facing a big challenge to transition to low carbon heating, EPCs could be a helpful tool for consumers looking to save money and improve their home's efficiency in the future,”  says Rocio Concha, Which? director of policy and advocacy.

“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.”

She suggests the next government after the general election must make EPCs a more reliable and useful tool for householders. 

What is an energy performance certificate?

Introduced in 2007, an EPC gives a judgement on a home’s green credentials.

An energy assessor will visit your property and analyse how efficient it is by looking at factors such as the building structure as well as how much insulation there is.

The EPC provides a rating of A for a high score and G for a low one.

The lower the rating, the more it could cost to heat or ventilate a property, while more work may be required to improve it.

How accurate are EPC ratings?

An EPC is required on property listings when they are put up for sale or for rent.

Properties rented out by landlords must also have a minimum EPC rating of E.

Some estate agents suggest more energy efficient homes attract a buyer premium.

But research by Which? warns that they can be riddled with inaccuracies and unhelpful advice that could cost homeowners when they come to sell or make home improvements. 

The consumer watchdog selected 12 Which? members who were homeowners across England, Wales and Scotland and booked EPC assessments on their behalf during February to March 2024 to find out how accurate EPCs are.

Their properties were built between 1650 and 1999 and ranged from a one-bedroom flat to a five-bedroom detached house. 

The analysis uncovered issues with the accuracy of the results and the recommendations that homeowners received.

One homeowner had their EPC survey done, but never received their certificate. The survey fee was refunded, but the homeowner was left in the dark about their home's energy efficiency. Of the remaining 11 participants, just one was ‘very satisfied’ with their EPC and only three said they were likely to recommend getting an EPC, based on this experience. 

Eight out of 11 participants told Which? their EPC did not appear to be accurate - they said the descriptions of key aspects of their home like the windows, roofs and heating systems were incorrect. 

Several participants also felt that the recommendations suggested were unaffordable.

Homeowner Megan Dobney achieved a D rating for energy efficiency for her two-bedroom Victorian terraced house in London.

The EPC recommended several improvements that could cost up to £26,700 and she would only see the property rise by one band from D to C. She could save around £920 a year through installing all these energy efficiency measures - meaning it could take up to 29 years to recover the cost, according to the research.

Another example found that an assessor missed that a home had solar panels and insulation so gave a property a lower rating.

Incorrect ratings could mean homeowners pay for works they don’t need or buyers make lower offers, leaving a seller with less from a sale.

How can energy performance certificates be improved?

Which? said the design and content of EPCs should be reformed to ensure it provides consumers with the information and advice they need and suggested making them more interactive so homeowners can add information.

The consumer group also called for a review of the training requirements for domestic energy assessor.

Estate agent trade body Propertymark has added its voice to calls for an overhaul, suggesting the   introduction of a Property Passport to increase the uptake of energy efficiency improvements. 

“This would enable information to be transferable across building owners and help maintain a long-term decarbonisation goal for the building,” says Timothy Douglas, head of policy and campaigns at Propertymark.

 “The process would not replace EPCs, but enhance them, creating an opportunity to capture EPC data digitally and add to it with other data over time. 

"A Property Passport would also provide detailed guidance on the actions required, and already undertaken, to improve the property, based on building fabric and operational data helping building owners and occupiers make decisions to improve the energy efficiency of buildings.”