‘Focus on hot water demand not generation in FHS’ says Triton

Properties built under the Future Homes Standard (FHS) could meet regulatory requirements without being fully optimised for real-world water and energy consumption, according to shower manufacturer Triton Showers.

The company is urging government and industry to place greater emphasis on reducing hot water demand, claiming that current assessment methods focus heavily on how efficiently hot water is generated rather than how much is actually used.

The firm has released research which reveals a significant disconnect between regulatory requirements and real-world building performance.

The report, Recognising Domestic Hot Water Demand Reduction in SAP 10.3, suggests that as homes become better insulated, hot water will account for a much larger proportion of domestic energy demand – more than half of household energy demand in FHS-compliant homes, compared with 35% previously.

Much of the policy debate continues to focus on heating systems, building fabric and onsite generation, even though space-heating demand could drop from around 58% to 41% as building fabric improves, the report warns.

The report highlights that showers and baths are responsible for more than half (55%) of domestic hot water demand, making them one of the most significant energy consumers in the home, yet current Standard Assessment Procedure (SAP) 10.3 calculations may enable developers to meet FHS targets through a combination of heat pumps, solar panels and batteries, even where little effort has been made to reduce underlying hot water demand.

Paul Ravnbo-West, market development manager at Triton, said:

The Future Homes Standard is a hugely important step forward for the industry, and we fully support its ambition to deliver lower-carbon homes. Yet there is a growing risk that we’re focusing too much on how efficiently hot water is heated and not enough on how much hot water homes actually need in the first place. If we are serious about reducing bills and improving resource efficiency, we need compliance frameworks that recognise technologies capable of eliminating demand at source, rather than simply producing hot water more efficiently.”

Paul also highlighted an area of SAP 10.3 that Triton believes requires greater attention. He said:

SAP is primarily an energy assessment tool and does not account for the financial cost of mains water supply or wastewater disposal. This omission is becoming increasingly significant as water bills rise. In some cases, it can even represent as much as, or more than, the energy cost of providing a shower. By overlooking these costs, SAP does not provide homeowners with a complete picture of the potential running costs associated with different water technologies. Greater recognition of hot water demand alongside energy demand would provide a more holistic assessment of household resource use and running costs.”

As part of its research, Triton compared a conventional mixer shower supplied by a heat pump and hot water cylinder with a high-efficiency shower system designed to work with wastewater heat recovery technology.

The latter approach saw:

• Annual shower-related energy use reduced from 649 kWh to 421 kWh
• Annual water use cut from 43,796 litres to 25,566 litres
• Carbon emissions reduced from 109 kgCO2e to 69 kgCO2e
• Combined annual water and energy costs cut from £357 to £220*

The study also found that a typical mixer shower operating at the minimum flow rate recognised by SAP uses around 60 litres of water during a seven-and-a-half-minute shower. By comparison, the high-efficiency shower in the trials used just 35 litres over the same duration.

Triton has identified several opportunities that would help SAP 10.3 and the future Home Energy Model (HEM) to better recognise domestic hot water demand-reduction technologies, enabling solutions that lower water consumption, hot water demand and wastewater volumes to meaningfully contribute to assessment targets.

Paul said:

Stronger alignment between energy- and water-efficiency regulations could also support housing delivery in water-stressed areas, where pressure on resources can affect the viability of new developments. The Home Builders Federation estimates that the proposed regulations could add around £3,100 to the cost of delivering a new home. Yet housebuilders specifying demand-reduction technologies, such as electric showers paired with wastewater heat recovery systems, can unlock water company incentives up to £3,500 per plot to encourage delivering water-efficient properties.”