This article is an extract of a paper presented at the 27th International Passive House Conference 2024 in Innsbruck. The full article is availabe in the conference proceedings [Jennings/Booth/Grove-Smith 2024], including an additional chapter on how airtightness was delivered on this challenging project.

St. Sidwell's Point
The first certified Passive House leisure centre in the UK.
Photo credit © Exeter City Council

St Sidwell’s Point Leisure Centre (SSP) in Exeter is the UK’s first certified Passive House leisure centre. The building provides two swimming pools (25 m and 20 m long, with moveable floors), a toddlers’ confidence pool, a 100 seat spectator area, a 150 station gym, a spin studio, a fitness/dance studio, a health spa with a hydro­therapy pool, changing facilities, a soft play area, a café and administrative offices. The project is featured in the online Passive House Database (ID 7393). It opened its doors to the public in the summer 2022 and is reported to be very popular amongst visitors.

As part of post-completion support for the client and operator, PHI has been analysing monitoring data that is being collected via the building’s BMS system. At the time of writing this paper (April 2024) one complete year of monitoring data was available (Jan-Dec 2023). As shown in the following sections the total energy consumption meets expectations and SSP is providing considerable savings compared to a typical leisure pool facility. The energy consumption data of 2023 reflects the building’s performance largely based on original project commissioning without major optimisation measures having been implemented since opening. The energy assessment and post-completion support is ongoing and it is likely that energy consumption can be lowered even further by adjusting and optimising controls.

SSP’s total absolute and specific final annual energy consumption for the year 2023 in shown in Figure 1, including the respective contributions from mains electricity and from gas. The project’s main heating and cooling system is an air source heat pump with two gas boilers to cover heating peaks. Due to some mechanical problems, thus far only approximately 50% of the ASHP's peak plant duty is operational. It is expected that a higher share of heating can be covered from the heat pump in the future, leading to a reduction in gas and also in total final energy demand.

The current analysis indicates that heating and cooling consumption are well aligned with expectations, whilst the electricity consumption is higher than anticipated. As expected and calculated with the multi-zone PHPP the highest energy consumption is caused by the space heating for pool halls, the pool water heating and shower water heating demand. High electricity consumption is not uncommon for projects of such size complexity, as it is difficult to capture all consumers and equipment runtimes during design stage energy modelling. A detailed analysis of the calculated energy demand and this in-use energy consumption data is yet to be completed for the different facilities and systems in the building.

Figure1: Measured final energy consumption of St Sidwell’s Point Leisure Centre, 2023. Left: Total final energy (mains electricity and metered gas consumption) shown as absolute and specific values. Right: Total final energy roughly divided into energy consumption for heating/cooling and other electricity uses. Treated floor area TFA = 4995 m², pool area = 663 m². Assumed calorific value for gas = 10 kWh/m³. © PHI

Benchmarking is an important exercise in order to assess how well a building is performing compared to expectations and typical building practices. For this building typology, however, comparisons are particularly difficult, as leisure buildings naturally vary in terms of their specific energy consumption, simply due to different combination of facilities included in the buildings, as well as different opening hours and usage patterns.

To put energy consumption of SSP into context, its monitored energy data from 2023 was compared with reported energy consumption of the Riverside Leisure Centre, a different leisure facility also located in Exeter. Riverside was originally constructed in 1984 with some refurbishment and upgrade works since then [ECC 2023]. It features a similar facilities mix to SSP but has a smaller gross internal floor area. One main difference is that the Riverside project also includes a sports hall. Furthermore, the two projects have very different heating systems: Whilst SSP uses electricity (air source heat pump) as the primary source of heating energy with gas boilers for peak demand, Riverside’s main heat source are two gas boilers, complemented with several small air source heat pumps, CHP microgenerators for backup power and a PV system.

All conclusions need to be drawn carefully and in context of these two specific projects. Even though SSP has a larger floor area, and the functional brief for SSP is theoretically more energy intensive than Riverside (e.g. more wet areas and no low intensity sports hall space), the project’s total annual energy consumption is significantly lower (57%) than that of Riverside. The electricity consumption in SSP is higher, which is likely the case mainly due to the different heating system. Notably, SSP has a fairly constant energy consumption over the course of the year, whilst Riverside has significantly higher energy consumption particularly during colder heating dominated months. This validates the effectiveness of the Passive House concept to considerably reduce the heating energy consumption.

Figure 2: Comparison of annual final energy consumption of Riverside and St Sidwell's Point Leisure Centres.

Figure 3: Comparison of monthly final energy consumption of Riverside and St Sidwell's Point Leisure Centres.

The in-use performance data shown in this artile provides proof of concept that Passive House successfully provides substantial energy savings also for this complex typology of leisure pool centres including indoor swimming pool facilities. This provides an immense opportunity for municipalities and for operators to save operational cost and carbon emissions. SSP being the very first certified PH leisure centre in the UK, there are many interesting learnings from the design process, as well as from first years of operation. We recommend taking a look also at additional literature provided below. Several similar facilities have been inspired by SSP's success story and are now in design or under construction, ranging from leisure centres to schools with indoor pools.

[ECC 2023] Futures, Currie & Brown, SDS Engineering Consultants: Exeter City Council Riverside Leisure Centre Decarbonisation Strategy Report; October 2023

[Gaertner/Osmundsen 2023] Gaertner, T,; Osmundsen, E.: Taking a Splash – Exeter City Council’s 12 Year Journey to Delivering the UK’s First Passive House Leisure Centre and Public Pool. In: Feist, W. (ed.): Proceedings of the 26th International Passive House Conference 2023 in Wiesbaden. Passive House Institute, Darmstadt, 2023.

[G&S/PHI 2023] Boon, G,; Fitzsimmons, J.; Grove-Smith, J.: St Sidwell’s Point Passivhaus Leisure Centre. In: Feist, W. (ed.): Proceedings of the 26th International Passive House Conference 2023 in Wiesbaden. Passive House Institute, Darmstadt, 2023.

[Jennings/Booth/Grove-Smith 2024] Jenning, P.; Booth, S.; Grove-Smith, J.: St Sidwell’s Point Leisure Centre: Airtightness delivery & one year of in-use energy performance. In: Feist, W. (ed.): Proceedings of the 27th International Passive House Conference 2024 in Innsbruck. Passive House Institute, Darmstadt, 2024.

Go to the overview of articles on Passipedia about swimming pools.

Go to the overview of articles on Passipedia about non-residential Passive House buildings.