Changes to regs would see heat pumps gain less credit for saving carbon than at present

Heat pumps could become substantially less attractive to the industry after the Building Research Establishment (BRE) proposed revised assessment criteria to measure the environmental impact of buildings.

The change follows a study published last year by the Energy Savings Trust which showed heat pumps were far less energy efficient than previously thought.

It found heat pumps produced around two and a half units of energy for every one used to run them, a figure far below the three to five units claimed by manufacturers. This figure forms the basis of the current calculations for heat pumps under the Standard Assessment Procedure (SAP) for buildings, which calculates environmental impact.

Now the BRE has published a consultation on changes to the SAP suggesting the credit given to heat pumps for reducing a building’s environmental impact should be downgraded. It said in future the SAP should reflect seasonal variations in the performance of heat pumps.

“The BRE are closing a loop hole,” said Mel Starrs, associate director at PRP Architects. “Previously you could put in a ground source heat pump and get credit for higher energy savings [than those generated].”

Starrs backed the BRE’s plans but said she was disappointed the BRE had not included tighter regulations on the fabric of buildings.

However, the consultation did include proposed changes to the timeframe of measurement of average energy performance, which would be measured over three years, not five years as it is currently. The document said this would improve the accuracy of these assessments.

It also proposed changes to include carbon emissions generated overseas and consideration of regional weather variations when calculating a building’s efficiency.

Starrs said she was also disappointed that the consultation did not include anything on measuring how the ageing of a building can reduce its efficiency.

“Studies have shown that the U-values [the assumed values for energy efficiency attributed to each element of a building] are out by quite a big margin and there had been talk of this being included in SAP,” she added.