Higher carbon reduction goals for new buildings cannot be assessed reliably, industry warns ministers

It will be impossible to meet proposed green standards for buildings until measurement systems are dramatically improved, the industry has warned the government.

In January, the government set out plans to increase carbon reduction targets for new homes by 8% and for new non-domestic buildings by 20% over 2010 levels, as part of changes to Part L of the Building Regulations.

The consultation on the proposals closed on 27 April.

But a letter to the government from a group including engineer Arup, contractor Laing O’Rourke, real estate firm Derwent London, developer Platform and architects Ian Ritchie Architects and Zaha Hadid Architects, claimed the assessment system is inadequate to measure targets.

Policies must be rethought to take into account economic realities

Peter O’Connell, Federation of Master Builders

It said the variation in results from different modelling software was “no longer tolerable” as it made it near impossible to judge whether a building was achieving the energy standards set.

The letter added that changing carbon dioxide emissions factors, which allow designers to compare the emissions rates from different power sources and feed that information into Part L models, were “extremely problematic”. It said: “Part L contains the most complicated and least transparent method of assessment of all the building regulations. This undermines the credibility of both the government and the engineering profession, and hampers our ability to provide transparent replicable advice to our clients.”

Jo Wheeler, senior policy officer at the UK Green Building Council, added that it remained unclear whether the performance gaps between models and completed buildings were due to modelling and assessment systems or the construction process.

Peter O’Connell, policy manager at the Federation of Master Builders, said the target to reduce carbon emissions from new homes was “completely unrealistic”.

“The housing boom is over. Policies must take into account economic realities,” he said.