The government’s target of cutting carbon emissions 20% by 2010 is being threatened by a delay in the introduction of energy regulations.

The government was expected to make an announcement about Part L to parliament this week, but the ODPM says that it will now announce changes to Part L during the summer recess.

Until the ODPM announces Part L methodologies and energy targets, the construction industry will not know how buildings should be designed to ensure compliance.

In a debate on the energy green paper, environment minister Elliott Morley said that energy regulations would come into force in April 2006, four months later than expected.

If the regulation comes into force after 1 January 2006, the UK risks non-compliance with the European Union Energy Performance of Buildings directive. The directive requires that buildings be classified with an energy rating and changes to Part L are intended to ensure this requirement is met.

In a statement the ODPM said: “We have consulted on the proposed change to the Building Regulations in order to introduce those changes in 2006. However, we have not yet set out the government response to this consultation and we will do so in the summer.”

Andrew Warren, director of the Association of the Conservation of Energy, said: “Manufacturers will have made a capital investment in low energy products in anticipation of a return over a certain time period. It’s an appalling signal for the construction industry. You will have substantially more emissions if there is a delay.”