Proposed changes to regulations 'will make buildings less energy efficient'

Damning assessment by group of leading architects and engineers describes government plan as 'a step backwards'

Proposed changes to building regulations in England and Wales are likely to make buildings less energy efficient not more, a group of leading architects and engineers has warned.

In a damning assessment of proposals to reform Part L of the Building Regulations, which sets the minimum energy performance standards for new dwellings, a growing coalition of professionals has described the changes as "a step backwards, in a climate where we need a huge leap forward".

"The proposals are framed as an improvement, but they actually represent a reduction in the energy performance standards of buildings," says Clara Bagenal George, a building services engineer at Elementa Consulting and founder of the London Energy Transformation Initiative (Leti), a voluntary group of more than 1,000 architects and engineers that has been calling for radical changes to how building energy consumption is assessed.

Under current regulations, all new building designs are assessed against a "notional" benchmark design, using parameters such as the thermal performance of materials, the orientation and size of the windows, airtightness and heating and ventilation systems (pdf). The proposed building must meet the performance of the notional design to pass the test.

Critically, the new changes to the regulations would remove something called the Fabric Energy Efficiency Standard, meaning a building designed next year could be allowed to perform much worse than one built in 2013, when the current standards were introduced. Similarly, a building that would fail to meet the current regulations would pass under the new system. Part L applies to all buildings, although the current consultation covers only dwellings.

Secondly, Leti warns that a proposed emphasis on overall carbon footprint will help to mask the actual energy performance of new homes. The government intends to introduce a new factor into the assessment, related to the energy efficiency of the grid, not the building itself. Because the National Grid has been rapidly decarbonising over the last few years, as more renewables have been connected, the new method of assessment would show that a home produced lower carbon emissions than before - despite the design being exactly the same.

"The new proposals totally mask the actual energy efficiency of a home," says Clare Murray, head of sustainability at architecture firm Levitt Bernstein and member of Leti. "They make the building look like it is performing better, when the reality is it could be much worse."