The cross-government definition of zero carbon is overwhelmingly likely to fall in line with the Department for Communities and Local Government's (DCLG) current definition, according to a leading sustainability expert and adviser to the Government and housing industry.

Simon Cross, associate director of the housing group at construction standards body the Building Research Establishment (BRE), said the Government would "go with the current definition contained in the Code for Sustainable Homes".

The Code for Sustainable Homes (CSH) was drawn up by the DCLG and published in 2006.

The code's highest rating, level six, is the department's current definition of zero carbon and allows homes that import energy from renewable sources elsewhere in the country, such as wind farms, to be defined as zero carbon. "It's likely that they will allow off-site renewables," said Cross.

The definition differs significantly from the Treasury's current definition, which stipulates that all energy "must be generated either in the home, on the development or through other local community arrangements". The CSH is based on the Ecohomes rating system, which was developed by the BRE. In 2007, then communities secretary Ruth Kelly announced that, from 2016, all new homes in England would have to be zero carbon.

A report from the DCLG published in the summer estimated that building to CSH level six would mean the cost of building a house would increase by 40-50 per cent. The final announcement from the Government on its agreed definition of zero carbon is expected imminently.