A recent study exploring the risks and impacts on the reliability of Energy Performance Certificates (EPCs) has uncovered a staggering amount of properties across the UK may be unwittingly let illegally.

An extensive study using Spec technology has estimated that poor measurement standards currently used by the property sector, has led to approximately 2.5m EPCs being inaccurately rated.

The report, entitled, Impacts of Inaccurate Area Measurement on EPC Grades explores how outdated techniques to measure floor space can have a significant impact on the accuracy of EPCs.

According to the study, 1 in 4 EPCs are mis-measured by at least 10% of their size. It also indicated that 1 in 4 property measurement reports are out by at least 100 sq ft, meaning there could be serious consequences on the validity of EPC ratings across the country.

With an estimated 1m properties that require an EPC to be legally let in the UK, approximately 33,000 E-rated properties are thought to be incorrectly rated, and therefore being let illegally. The incorrect measurements leading to miscalculated EPC ratings also result in inflated mortgages or under insured houses, affecting owners’ ability to qualify for ‘green mortgages’, that financially benefit those with better performing properties.