The problem with Energy Performance Certificates

Energy Performance Certificates (EPCs) were designed as a simple way for potential buyers and renters to compare the energy efficiency of homes.

In recent years they have been used in a much wider context than originally intended. EPC ratings now play an important role in government policies geared towards decarbonising homes and delivering Net Zero.  

However, our research found that some EPCs can be inaccurate and unreliable, and therefore not nearly as useful as they should be. 

More on this: how to get an Energy Performance Certificate

What is an EPC?

EPCs were introduced in 2007 as part of the Home Information Pack (HIP), to help prospective buyers compare the energy use and environmental impact of different properties. 

Although the requirement for a HIP was later scrapped, a valid EPC is still needed when selling or letting a home.

They give homes a rating between A (very efficient) and G (inefficient) and recommend the most cost-effective ways to improve energy efficiency.

EPCs have the potential to be a helpful tool for homeowners looking to save money, improve their home's efficiency and reduce their carbon footprint – but only if they offer reliable information.

Cutting your energy costs: how to make your home more energy efficient and 10 ways to reduce your energy bills

Low levels of satisfaction

Which? selected 12 homeowners across England, Wales and Scotland and booked EPC assessments during February and March 2024, to find out how accurate EPCs are and how useful the recommendations might be. 

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

We uncovered issues with the accuracy of the EPCs and the recommendations that homeowners received.

One participant had their home surveyed but never received their certificate. The survey fee was later 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. 

Inaccurate results

Most participants (eight out of 11) told us their EPC did not appear to be accurate – they said the descriptions of key aspects of their home, such as windows, roofs and heating systems, were incorrect. 

One EPC contained several significant errors, which we pointed out to the assessor. These were corrected and a new EPC was issued, with the energy efficiency rating moving up two bands, from D to B.

This shows the importance of checking your EPC and getting it corrected if necessary. 

An incorrect EPC might recommend inappropriate building work that could prove to be costly and unnecessary.

A better EPC rating can mean your home commands a higher price if you choose to sell, and may make it more attractive to prospective buyers or tenants.  

Want to hear more about home energy surveys? The Which? Shorts podcast has the full article 'How energy efficient is your home?' from our July Which? magazine.

Unhelpful recommendations

Several participants felt that the recommendations suggested on their EPCs were unaffordable. 

One EPC recommended changes that could save £920 a year on energy bills; however, the total estimated cost meant it could take up to 29 years to break even on the outlay. 

The homeowner said: 'The recommended changes are extremely expensive, generally for small savings each year, and would require massive disruption.'

Several EPCs made similar recommendations and, while the projected savings were calculated for each individual property, the same wide price range was quoted for all. 

For example, solid wall insulation was recommended at a cost of £4,000-£14,000 for both a two-bedroom mid-terrace and a four-bedroom detached house. 

Such a broad range of prices could put people off, when the costs for improving their own home could be much lower than the maximum indicated.

Read more: solid wall insulation costs and savings

Accreditation scheme’s response

Only qualified Domestic Energy Assessors (DEAs) can produce EPCs for homes. There are several accreditation schemes that provide DEA training and certification, and carry out quality assurance auditing on a proportion of all EPCs that are issued.

The majority of the EPCs in our study were produced by DEAs registered with Elmhurst Energy, which is the largest of the accreditation schemes and has around 7,500 DEA members. 

When we shared our results with Elmhurst Energy, it was unsurprised by the low levels of satisfaction. Elmhurst is supportive of reforms and believes EPCs are currently unclear and often misunderstood by consumers.

Stuart Fairlie, Elmhurst Energy managing director, said: 'We’re disappointed to see the Which? EPC assessment results and can understand why homeowners might want information to be presented in a clearer way, with straightforward recommendations. 

'To identify inaccuracies on EPCs, we run a smart, ‘risk-based’ auditing programme which flags those with potential errors. If defects are found, we require reassessment by the energy assessor. 

'We continue to champion reform of the wider EPC system including ensuring quality training standards. This has been on the agenda since the government’s 2020 EPC Action Plan and it's imperative for the next government to quickly deliver.'

Following our discussions with Elmhurst, they carried out audits on four EPCs that we brought to their attention. 

In one case, the EPC was correct and no further action was required; however, three out of the four were found to be inaccurate. Two of the EPCs have been or will be re-lodged to correct the errors (including the one mentioned above under 'Inaccurate results'). 

The third property requires another visit for reassessment before an updated EPC can be produced.

Elmhurst have confirmed that it is unlikely that any of the three inaccurate EPCs would have been caught by the standard auditing process. If the errors had not been flagged up by us or by the homeowners, these EPCs would not have been corrected.

Which? is calling for better EPCs

We’re calling for the government to reform these certificates to make them a more reliable and useful tool for householders.

With millions of families across the UK worried about high energy bills, EPCs could provide valuable information on how people can save money and improve their home's efficiency. 

The government should review the auditing of EPCs and the training requirements for Domestic Energy Assessors, to ensure that they have the skills needed to complete reliable assessments. 

EPCs should also include clear, actionable advice for consumers, such as low-cost measures they can take to improve their home’s energy efficiency as well as more expensive options.