Renting out properties with bad insulation and heating has been prohibited since April

Are some landlords and agents fiddling new rules that ban them from letting out properties that are poorly insulated and inefficiently heated?

Since the start of April, landlords have been prohibited from renting out “sub-standard” houses and flats, which, in this context, means those that don’t meet minimum energy-efficiency requirements.

However, Guardian Money has been shown an example of a flat being listed on a letting agent website where the energy efficiency “score” appears to have been fraudulently changed to allow it to be advertised.

The reader who brought the listing to our attention says the property – a one-bedroom flat in west London – has had its energy efficiency rating “miraculously increased” from 23 on the official certificate to 40 on the agent’s website.

Landlords can be fined up to £4,000 if they let a sub-standard property in breach of the regulations, and can be “named and shamed” on a public register.

But when Money tried to search the register, we could not find details of a single landlord issued with a penalty.

These new rules relate to the energy performance certificate (EPC) that outlines the energy performance of a property, from A (most efficient) to G (least efficient), and recommends improvements that could be made.

Virtually all homes sold, rented out or built since 2008, have to have an EPC, which must be available to a prospective buyer or tenant.

Since 1 April, landlords have been banned from granting a tenancy to a new or existing tenant if the property has an EPC rating of band F (a score of 21-38) or G (1-20).

The government says F- and G-rated properties waste energy, impose unnecessary costs on tenants and the wider economy, and contribute to avoidable greenhouse gas emissions.

So how many of these sub-standard properties are out there? According to letting agent body Arla Propertymark, it’s as many as 300,000.

However, there is a rather large elephant in the room in the form of an exemption that many landlords can use to get out of doing the work. Under the rules, landlords of F- and G-rated properties are only required to make the necessary improvements where this can be done at “no cost” to themselves.

In other words, the ban doesn’t apply if the landlord has been unable to access third-party funding – for example, Green Deal finance or a local authority grant – to cover the costs. However, the government has proposed making changes to this.

The reader who contacted us says his daughter will soon be leaving the west London flat, which has an EPC at the low end of the F range (23). However, the letting agent is advertising it on its website with an score of 40 – putting it in the E band.

The reader says he is certain no improvements have been carried out – and, as his daughter lives there, he should probably know. He adds that the letting agent is “using fraudulent EPC information”.

The man says he has not raised the issue as he does not want to jeopardise the return of his daughter’s deposit. His advice to others is: “Don’t just take the word of the agent that the EPC is what they say it is.”

There is an easy way for anyone looking to rent or buy – or is simply a nosy neighbour – to check the EPC of any property.

Go to epcregister.com, click on “retrieve report using property address” and type in the postcode or address, and you can then view the EPC for that property (if it hasn’t been sold or rented out in the last decade, it may not be on the system).

If the EPC rating of the flat highlighted by the Money reader has been deliberately changed to allow it to be rented out again, the local authority could impose a penalty of up to £4,000 and publish details of the breach on a publicly accessible part of what’s known as the “PRS exemptions register”.

The public can search this register (at prsregister.beis.gov.uk) for penalty notices – but when Money looked this week, we couldn’t get it to throw up details of a single landlord that had been punished, no matter what we keyed in.