NET ZERO SYSTEMS & SOLUTIONS


Designing Net Zero hot water systems in leisure buildings


For contractors and specifiers working on leisure projects, domestic hot water is increasingly part of the net zero challenge. From seasonal shower blocks to sports pavilions with sharp post-match peaks, successful design depends on understanding demand, storage, recovery and how heat pumps can work alongside on-site renewables, says Andy Green, head of technical solutions at Baxi


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n leisure buildings, particularly where showers are central to the user experience, domestic hot water (DHW) can represent a significant share of total energy use. All-electric solutions, typically involving heat pumps combined with storage and renewable energy technologies, offer opportunities to move to net zero operation DHW systems. But to achieve the most efficient and cost-effective system, it’s important to understand the usage and occupancy profiles of the facilities. This includes how intense the peaks are, what storage volume is realistic, how quickly the system must recover and whether complementary solar PV panels or battery storage can improve performance.


Designing for seasonal sites


Take caravan and camping parks. The occupation profile of these facilities is mainly seasonal, from March to October. In terms of DHW usage patterns, the total volume of hot water used is high, while demand can be spread over several hours or follow a morning and evening peak pattern. In this scenario, an air source heat pump (ASHP)


paired with generous storage can be an effective all-electric option, where the system has time to preheat water efficiently and recover between busy periods. For installers and designers, the main


consideration is the relationship between stored volume and recovery time. The design should therefore ensure that the ASHP is prioritised to preheat the water in the cylinders and that the heat is recovered in time to meet the next demand. Immersion backup can also be used to provide top-up support during exceptional demand and help with pasteurisation where required. A case in point is Pembrey Country Park, where a new shower facility for Carmarthenshire County Council uses a Baxi Auriga HP 40 ASHP with a 1,000-litre Megaflo Flexistore cylinder, specified by M&E Consultants Pursey and Ball, to serve male, female, family and accessible shower areas. Water- saving fittings and 10 kW of solar PV contribute to the net zero operation, supporting the Council’s wider net zero goals. The project is a useful reminder that integrating the DHW system with the wider electrical strategy can strengthen the business case, especially where on-site renewables are available. Advantages of


12 July 2026


www.heatingandventilating.net


Eaton Park Pavilion


this DHW system design are the high efficiency it delivers and low standing losses.


Designing for fast recovery


Sports pavilions present a very different challenge. Demand can be minimal for much of the week, then rise sharply when several teams need showers within a short window. Designers therefore need to think carefully about a system that will meet the short but intense high DHW usage in the most efficient way. Simply adding more storage is not always the most efficient answer, particularly where occupancy is intermittent. Equally, fully instantaneous electric systems can place heavy demands on the supply. In smaller leisure buildings, a balanced all-electric strategy may work better: combining heat pumps with compact storage, controls and smart use of immersion backup to improve recovery without excessive standby losses. That approach can be seen at Eaton Park


Pavilion in Norwich, where Norwich City Council adopted an all-electric system designed by as part of a wider refurbishment. The listed status of the building added design constraints, including the need to limit the visual impact of roof-mounted plant, but the final solution, designed by JD Gray Associates, still delivered two Baxi HP50 13 kW ASHPs, two buffer vessels and two 300-litre ASHP cylinders. Solar PV and battery storage add another useful dimension. At Eaton Park Pavilion, stored electricity can help the system recover during peak periods when several teams need showers in quick succession. For contractors and specifiers,


the lesson is that DHW performance increasingly depends on how well the hot water system is integrated with the site’s wider electrical and renewable strategy.


Designing for success


These two projects show that while there is no silver bullet, occupancy and load profile, available electrical capacity, storage strategy, controls and the contribution that PV, batteries or off-peak tariffs can make to overall performance will all influence the design. In some schemes, an all-electric solution will be the clear next step; in others, the route may need to be phased. As an experienced heating and hot water solutions provider, we at Baxi look forward to supporting specifiers and contractors with our technical design expertise, wide portfolio of low- carbon solutions, commissioning and service packages to achieve and maintain the best solution every time.


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