VOICES | ANDY GREEN What new energy regs mean for water heaters Non-condensing water heater replacements will be banned under upcoming Building Regulations. Baxis Andy Green looks at the implications of the new energy efciency standards in Approved Document L O n 15 December 2021, the government published updates to Approved Document L of the Building Regulations, which sets the standards for the energy performance and carbon emissions of new and existing buildings. One of the changes relates to stricter thermal efficiencies for domestic hot water systems. From 15 June this year, direct-fired water heaters must achieve a minimum heat generator seasonal efficiency of 91% (gross calorific value, GCV) for natural gas and 92% GCV for liquefied petroleum gas (LPG). For indirect-fired water heaters, the minimum heat generator seasonal efficiency is 91% (GCV) for natural gas and LPG. The new standards apply to existing and new non-domestic building stock. What will the stricter standards mean in practice? Effectively, it will remove the option to carry out like-for-like noncondensing water heater replacements in the majority of non-domestic buildings. Only in very exceptional circumstances, where a condensing water heater replacement is deemed not suitable by the building control body, may a minimum seasonal efficiency of 80% for gas, or 79% for LPG, be used. The uplift is part of the governments roadmap to reaching the UKs net zero target by 2050, and represents an important step towards more energy-efficient existing non-domestic buildings. Direct-fired water heaters are an efficient, cost-effective means of delivering large volumes of sanitary hot water, and hospitals, hotels and leisure centres with their high demand for instantaneous hot water are just some of the buildings that rely on this technology. Up until now, most manufacturers and suppliers have offered a choice of condensing and non-condensing models. Condensing water heaters can capture and reuse latent heat that would otherwise be lost through the flue. As a result, they are up to 20% more efficient than non-condensing models. Units like the Andrews Water Heaters ECOflo, MAXXflo EVO and SUPAflo EVO can achieve efficiencies of up of 98%. The energy-saving benefit of switching to more efficient condensing units is evident. However, many organisations still rely on the ability to carry out like-for-like non- condensing water heater replacements when the existing equipment comes to the end of its serviceable life. As no major work is involved, the appliances can be replaced quickly, with minimal disruption to the daily operation of the building. While the move from non-condensing to condensing water heaters can be relatively straightforward, certain factors, such as flueing and condensate arrangements, will need to be assessed on a project-by-project basis. So, our advice is to work with building owners now to implement an asset management programme. With regular condition surveys and plant asset inspection, they will be sufficiently informed to plan ahead to future-proof their hot water systems. Switching from a reactive to a proactive approach will enable them to prepare for change, and to budget for future upgrades. Even on the few projects where exemptions may apply, forward planning is important. Early engagement with building control will be critical if heating engineers are to ensure they are satisfied with the recommendation and avoid any risk of censorship. With challenges come opportunities. An upgrade will encourage a reassessment of the buildings hot water requirements. Many firms will have experienced changes in building occupancy over the past two years. Ultimately, the revised calculations could point to a smaller water heater now being required, which would reduce initial capital expenditure and longer-term running costs. For designers, the shift to condensing technology brings the chance to relocate plant to make better use of space. In hotels, for example, the original plantroom could be converted into an extra bedroom. Budget permitting, there may even be the option to integrate low carbon air source heat pumps with condensing water heaters in a hybrid system, for a greater reduction in the carbon footprint. But forward planning is essential and the clock is ticking. What nobody wants is for buildings to be left in an emergency situation with no hot water supply. To protect their operations, we must encourage them to start plotting a robust upgrade plan now. Andrews Water Heaters is part of Baxi Commercial Solutions. The energysaving benefit of switching to more efficient condensing units is evident ANDY GREEN is technical director at Baxi 52 April 2022 www.cibsejournal.com CIBSE Apr 22 pp52 Andy Green.indd 52 25/03/2022 18:02