Housebuilders will save almost 拢1bn by exploiting a loophole allowing them to bypass tough energy standards introduced in October

A survey carried out by local authority building control body LABC revealed that housebuilders had pre-registered 178,400 homes before the introduction of 2010 Part L in October.

Once registered, the loophole allows housebuilders to build to 2006 Part L providing they start work on site within a year.

After work starts the whole scheme is allowed to comply with 2006 Part L regardless of how long it takes to complete.

Local authorities reported thousands of plots were registered in the run up to the deadline, including many without planning permission.

LABC said 178,400 homes were registered between 1 July and 30 September 2010 compared with 24,240 for the same period last year. It also said building to lower energy standards would save housebuilders 拢5,000 a home on average, which equals 拢892m.

LABC said it had only surveyed half the local authorities in England in Wales so the final numbers of pre-registered homes could be much higher than shown by the statistics.

Paul Everall, chief executive of LABC, blamed the communities department for the loophole. He said: 鈥淭he Department for Communities and Local Government has created a situation where tens of thousands of new houses are likely to be built to old standards over the next few years.

鈥満诙瓷缜� Regulation changes have been careful to create a level playing field for industry. In the competitive housebuilding market, it is vital that no advantage can be won or lost according to how legislation is introduced.鈥�

He added that the NHBC had been privately briefed by the communities department about the arrangement. The NHBC then wrote to housebuilders alerting them to the loophole in a bid to gain market share.