A fifth of commercial and residential property may be excluded from the rental and lease market by 2015 unless owners move quickly to comply with new energy-efficiency rules.

Legislation is already in place which states buildings with a rating of F or G on their Energy Performance Certificate (EPC) cannot be let out after 2018, without works having been carried out to raise the rating level.

But property and construction consultancy McBains Cooper says it believes the government may actually bring this legislation forward to 2015 as part of the UK’s commitment to reduce carbon emissions.

“[Properties that] might be considered an asset, may actually be a liability," said Anthony Coumidis of McBains Cooper. "If a commercial or residential property doesn’t comply, and its owner for whatever reason wants to switch it to being let out after the anticipated deadline, then they can’t. The owner can renew existing leases, but that owner is potentially exposed should tenants decide to move out of an F- or G-rated building after the deadline date.

“We estimate that around one in five buildings fall into the F/G EPC category, including many listed or historical properties. Property owners therefore have to raise the efficiency ratings of F/G level buildings, or face them having to stand empty. In some cases, planning permission may be required, which, bearing in mind upgrade designs may need to be drawn up, can mean months of delays before work can actually start.”