The UK Green Building Council has called on politicians to back changes in a government bill which would make the Code for Sustainable Homes’ rating system mandatory for all new homes.

Council chief executive Paul King made his appeal as the Housing and Regeneration Bill, which the government claims contains a mandatory code commitment, received its second reading in the House of Commons. Currently, Code ratings operate under a voluntary basis.

Mr King said the bill’s current wording was confusing as it meant new homes could still be sold without a Code sustainability certificate. Written statements could be provided instead, which say there are no certificates for the property.

“Mandatory rating should mean mandatory rating. If the current wording of the bill remains unchanged, home buyers – most of whom will not have come across the Code before – will be left in a state of confusion.

“If a new home has not been built to the Code then the acompanying documents should state explicitly that the home fails the Code for Sustainable Homes, or achieve no stars.

“They should be left in no doubt that a home that has not been assessed against the Code has only been built to minimum Building Regulations and is therefore not a sustainable home.”

The bill, which must go to committee stage next, also outlines the government’s commitment to build three million new homes before 2020.