Those involved with the construction of new build dwellings will be familiar with Part L of the Building Regulations. This approved document sets the standards for the energy performance of both new and existing buildings.
With the introduction of the Future Homes Standard in 2025 the energy requirements in Part L are being progressively ramped up to ensure that new build homes are future-proofed with low carbon heating, micro-generation devices and world-leading levels of energy efficiency. Reducing energy use, embodied carbon and water consumption remains high on the government’s agenda and is seen as a vital first step to ensure the construction industry can deliver the significant reductions necessary by 2030 in order to have a realistic prospect of achieving net zero carbon for the whole UK building stock by 2050.
Hot water demand in a future home
Improvements in fabric efficiency will no doubt help future homes to save significant levels of energy, however, the demands of the householders remain unchanged. For example, in the case of a super-insulated dwelling Domestic Hot Water (DHW) requirements will be the same as a traditional-built dwelling e.g. similar number of occupants with the same water-use behaviour i.e. showering. This presents an interesting shift in household energy demand. As building efficiency improves so the percentage share of energy attributed to hot water will increase, potentially making hot water generation in Future Homes the largest portion of the household energy budget.
It is therefore important that in addition to Modern Methods of Construction (MMC), ‘Clean Growth’ technologies such as high efficiency showers, should be considered to help achieve future EPC targets.
The future role of showers
In an average house hot water use accounts for 23% of the total energy use. According to the Energy Savings Trust 50% of the generated hot water cost is attributed to showering – making showers alone responsible for 11.5% of the overall energy use. In a ‘super-insulated’ dwelling, hot water use has been calculated to be as much as 49% of the total energy use.
Figure 1.0: As fabric efficiency improves it is estimated that showers will be responsible for a staggering 24.5% of the total dwelling energy use.
In addition to the tightening of energy requirements in Part L of the Building Regulations, there is a requirement for housebuilders to comply with Part G, specifically G2 concerning water efficiency. For showers to meet Part G2 there is a ‘maximum consumption’ or ‘flow rate’ requirement of 10 litres/minute (to meet the standard ‘notional’ level of 125 litres/person/day) or 8 litres/minute (optional ‘higher’ level of 110 litres/person/day).
In a domestic refurbishment where the ‘Wat 01’ water calculator is used Kelda’s air-powered showers operating at less than 6 litres/minute exceed conformity and achieve the highest BREEAM ‘Excellent’ standard – without compromising on showering quality.
Using less water is not only a key requirement for compliance but also offers additional benefits:
• Space heating – allows the specification of a smaller hot water cylinder – a key consideration when using heat pumps where 200-litre capacity is now commonplace.
• BREEAM status: Together with other bathroom fittings specified to ‘Excellent’ and WC room, kitchen and utility room fittings specified to ‘Good’ Kelda showers can help minimise the dwelling consumption of potable water to less than 96 litres/person/day – scoring maximum credits and achieving BREEAM ‘Outstanding’ standard.
• New build “infrastructure” discount: In response to water scarcity water companies, such as Anglian Water, are incentivising developers, up to £740 per plot, to build new houses to a water efficiency standard of 100 litres/person/day (10 litres below the optional ‘higher’ level).
“In a domestic refurbishment where the ‘Wat 01’ water calculator is used Kelda’s Air-Powered™ showers operating at less than 6 litres/minute exceed conformity and achieve the highest BREEAM ‘Excellent’ standard – without compromising on showering quality.”