Consultants and manufacturers are still unable to use computers to calculate Part L compliance for complex buildings because software has not been delivered by BRE.
Special computer programs required to calculate Part L compliance for buildings with different mixed uses have not yet been released because BRE is working on their finer points.
Alan Scupham, offsite construction systems manager at manufacturer Kingspan, said his company could not calculate compliance until the new module was delivered.
He said: "Everything is on hold until we get the software. The old one just doesn't work. Confidence in it is slipping down the drain but the latest revisions will solve a lot of problems."
Part L could cost the industry more than £1.2bn a year, according to a regulatory impact assessment by the ODPM.
The extra costs will particularly affect the commercial sector, which will have to spend an extra £309m a year on new buildings and £358m on refurbishments. Refurbishing industrial buildings is expected to cost £116m a year.