Stephen Matthews, CIBSE chief executive, said accredited assessors would face a “real challenge” in meeting demand ahead of the October 1 deadline while others within the industry have said it will be impossible.
The certificates, which show the energy usage and efficiency of a building, will be required for all public buildings and those occupied by public authorities of more than 1,000 metres square which are frequently visited by a “large number of people”.
Unlike Energy Performance Certificates they must be in place by the deadline rather than when a property owner buys, sells or lets the property.
CIBSE is one of 12 companies and bodies approved to provide DEC accreditation training, but the Department of Communities and Local Government (DCLG) has been slow to provide vital guidance, software and promotion.
Mr Matthews said DCLG had left things “a little late” and added: “It seems to me the assessors will be very busy. This is a step into the unknown.”
On Tuesday DCLG finally released the software updates to enable assessors to complete their accreditation training. A department spokesman said it expected the first DEC to be lodged by Wednesday or Thursday.
Paul Martin, managing director at Team Energy and chairman of the monitoring and metering group at the Energy Services and Technology Association (ESTA), said: “This is arguably one of the most interesting pieces of legislation of the past 25 years. It will stimulate awareness and investment in carbon reduction.”
But he added there was not enough time to ensure all public buildings would secure DECs by October. “It is not at all achievable,” he said.
Team Energy has developed its own software and has trained up to 22 people including its own staff and local authority workers and Mr Martin expects them to receive CIBSE accreditation shortly.
He said some local authorities had embraced the issue, but others had been slow off the mark.
Mr Martin added that aspects of the legislation were “ill-defined” so it was difficult on some complex sites to decide which buildings should be assessed individually, which could be grouped together and which did not fall under the guidelines.
He added: “I would suggest we need a little bit more guidance from the Government to make sure that two assessors visiting a site will come up with the same number of buildings and the same ratings.”
Richard Hipkiss, from i-prophets energy services, one of the first low-carbon energy assessors to be accredited by CIBSE, said more needed to be done to promote the positive message of having a certificate.
He said he hoped DECs could be a focus for facilities managers and public authorities to improve the performance of their buildings especially as they had to be renewed annually. But he said it was down to individual authorities to take advantage of the DEC process.