Extensions to buildings will not require contractors and designers to reassess the energy efficiency of the whole building before proceeding.
Renovations and extensions, referred to as “consequential improvements”, have been left out of updates to building regulations unveiled at the end of last week.
The government is consulting on moves to improve the energy efficiency of buildings and on ventilation, as part of a goal to make reduce energy usage in new buildings by 25 per cent from October 2010.
The new Part L requirements were expected to include the extensions requirement.
As well as the energy efficiency changes, there were other moves to update ventilation requirements.
Inbuilt chief executive Dr David Strong said that the absence of the improvements requirements was a “cop-out”.
“There is a window of opportunity to get this issue included as part of the revision of Part L. Building regulations are the only mechanism for that and if consequential improvements are not included now they cannot be considered until 2013,” he said.
He also said that the rules had failed to strengthen controls on summertime overheating, creating the possibility that many energy efficient buildings could be cheap to heat in winter but intolerable at other times.
Association of Consultant Approved Inspectors spokesman Geoff Wilkinson said one problem was understanding: “One of the most pressing issues is the extent of recognition among jobbing builders and the general public that certain works, e.g. previously unregulated fabric renovations, now fall within the regulations. The consultation also proposes a range of measures, including a strategy for training and dissemination, designed to further improve the level of compliance and performance in buildings.”
A spokesman for the Department for Communities and Local Government said that the improvements issue “will be considered as part of a future consultation. We still have not got a date for when that will be.”