The industry has hit out at the ODPM because unclear guidance on Part L of the Building Regulations is threatening to delay projects.

The ODPM's handling of the implementation of the energy regulation could result in projects being put on hold because there is no version of Part L to comply with.

Building control bodies Local Authority Building Control, the Association of Consultant Approved Inspectors and NHBC have jointly called for an urgent review of the implementation process, condemning it as "both unworkable and unenforceable".

The process announced by the ODPM last week says that schemes designed using the 2002 version of Part L that start on site after 6 April must have their full plans approved by building control before that date. Schemes approved after 6 April will have to comply with 2006 Part L.

However, the final 2006 version has not been published, and the software for calculating compliance has not been formally approved.

David Mitchell, the technical director of the Home Builders Federation, said it was already too late to get an application approved by 6 April, and this would prevent housebuilders starting work on site.

Every day Part L isn’t there, that’s 410 fewer houses

Dave Mitchell, HBF

He said: "If the industry is building 150,000 houses a year that works out at 410 a day. Every day the new Part L is not there, that's 410 fewer houses."

The delay has also angered other sectors of the industry. Peter Caplehorn, technical director of architect Scott Brownrigg, said:

"As far as I am concerned it is sheer lunacy. We are still in the position where we do not have the software and the approved document isn't there. I suspect quite a few projects will be put on hold."

Caplehorn said the only alternative to putting projects on hold was to overdesign them to guarantee compliance with the new version of Part L.

The building control bodies have called for an urgent meeting with housing minister Yvette Cooper.