A software correction has resulted in a boost in the energy credits for waste water heat recovery (WWHR) within a standard assessment procedure (SAP) calculation by up to 17%.

SAP is the official government methodology for measuring the energy performance of a new home and is a mandatory requirement of building regulations in the UK.

The uplift applies to all properties that have showers in rooms with baths, something that had been unaccounted for in the previous calculation framework.

The revision will also increase the overall SAP score by 1% which could save developers using the technology over £100 for every home they build.

This is because the boost may provide them with enough credits to pass recommended targets so they won’t have to spend money on installing additional energy saving technologies or longer WWHR devices.

WWHR devices are heat exchangers which use the heat from outgoing warm waste water to pre-heat incoming cold fresh water. They are most commonly used in residential applications where it is connected to a house’s shower and water heater.

WWHR is already one of the most cost-effective ways of boosting a SAP score and is recommended by the National House Building Council (NHBC) as a method that can be used to pass Building Regulations Part L.

“We welcome this move as it will bring down build costs for developers and help them to achieve compliance with certain house types which may have otherwise failed,” said Ashley Prescott, a director WWHR manufacturer at Power-Pipe UK.

“It goes without saying that this is a major step for our industry as the change will make WWHR even more cost-effective and allow it to get greater recognition across the board for its valuable energy efficiency contributions.”