The design concept draws on local form, colour, structure and materiality. A stacked layout was adopted to make full use of the 9,000 square metres available, with an integrated interior design strategy
THE largest of its kind, the £50m Eclipse Leisure Centre in Spelthorne is the first 50/50 wet and dry leisure centre in the UK to be designed to Passivhaus standards – setting the standard for sustainable, community-oriented design.
Designed by AJ100 practice GT3 Architects, the centre has raised the bar for low-carbon sport and leisure facilities, blending a people architecture approach with industry-leading Passivhaus design techniques. The now-open centre is currently awaiting full certification from the Passivhaus Institute and is expected to save up to 50-60% in typical operational usage, and up to 40% in comparable water usage.
The design details
Looking to create an exciting new leisure destination flexible enough to meet the evolving and varied needs of the growing community, Spelthorne Borough Council first approached GT3 in 2017. Extensive community consultation followed, including physical workshops, engagement sessions and online and doorstep surveys to ensure the design suited all stakeholders.
Mark Gowdridge, director at GT3 Architects, said: “Any good design starts with active consultation. One of the great successes – before Passivhaus was even mentioned – was prioritising hard-to-reach groups in the community. Understanding why typically underserved groups struggle to use and enjoy traditional leisure facilities led to key design choices, including stronger park connections, accessibility and inclusivity that goes far beyond standard building regulations and environmental concerns across the interior.”
The result is a state-of-the-art facility featuring an eight-lane swimming pool with a 250-seat spectator gallery, a dedicated learner pool with full-width self-depositing steps, a children’s splash zone, steam room and sauna. Fitness enthusiasts benefit from a new 200-station gym, three studio spaces – including a spin studio – and two physiotherapy consulting rooms.
Elsewhere, Eclipse offers a six-court sports hall with seating for 200, three adaptable squash courts, a Clip’n’Climb interactive climbing wall, a 100-cover café and soft play areas for community use. Smart spatial planning maximises every level of the site, including four rooftop artificial pitches and dedicated rooftop community gardens.
The design concept draws on local form, colour, structure and materiality. A stacked layout was adopted to make full use of the 9,000 square metres available, with an integrated interior design strategy ensuring visual consistency throughout. The building envelope features a thoughtful mix of brick, glazing, timber louvres and metallic facades, while windows are detailed with encased glazing and timber louvres for both function and aesthetic appeal.
Inclusive design elements such as Makaton signage and movable studio walls enhance accessibility, and LED-lit sports courts improve visibility for individuals with visual impairments by clearly highlighting court lines. The overall design is unified by a strong visual identity and was delivered in phases to allow the existing centre to remain operational during construction.
Mark continued: “This has been a milestone project for GT3 and it’s extremely rewarding to see Eclipse now open to the public. The work that the whole team has put in over the past few years – through COVID, the declaration of a climate emergency and rising energy costs – has gone beyond designing state-of-the-art sport and leisure facilities. This is a blueprint for the new wave of leisure in the UK.”
A partnership approach to introducing Passivhaus
In 2020, it became apparent that Eclipse could play a leading role in meeting the council’s net zero ambitions. In collaboration with Passivhaus specialists at fellow architects Gale & Snowden, GT3 revised the design for Eclipse to meet the rigorous standards required for Passivhaus certification – taking lessons learned through from Gale & Snowden’s previous experience. The resulting design is expected to save up to 60% in typical operational energy usage, and up to 40% in comparable water usage.
Contractor Willmott Dixon was brought on board to deliver the high-performance thermal envelope and well-designed thermal bridging details, which help reduce the high energy demands typically associated with leisure centres, while also preserving the building fabric.
Airtight construction minimises the risk of warm, moist air infiltrating the structure and triple glazing combined with high levels of insulation significantly reduces condensation risks. Eclipse has achieved one of the best air tightness scores globally for comparable leisure facilities – delivering a 90% improvement over standard regulatory requirements. Additionally, the building achieves a 30% reduction in total embodied carbon, aligned with LETI standard guidance.
Products were specifically sourced to further reduce energy and water usage, including an innovative microfiltration system that removed contaminants from water reducing the levels of chlorine required. This feature not only reduces operational energy but also makes swimming far more accessible for those with skin or breathing conditions. Elsewhere, grey water harvesting, low-water-usage toilets, sinks and showers add further water savings.
Josh Wardle, building biologist and certified Passivhaus specialist at GT3 Architects, said: “We took an extremely detailed approach to make sure we met the high standards required for Passivhaus certification, with more than 500 drawings created and very controlled standards in place.
“Mapping complex technical requirements to such a mixed wet and dry leisure typology was an exciting challenge, and one that pushed us to look at new and better design techniques and approaches. These techniques are now being applied to leisure facilities across the UK – not just those looking to achieve certification. One of the most enjoyable areas was understanding how the technical decisions and learnings needed for Passivhaus could also support the social ambitions and ‘people architecture’ themes agreed at the project’s outset.
“By optimising orientation, glazing ratios, internal thermal zoning and incorporating low-energy systems along with heat recovery processes to transfer energy between zones, the design achieved operational energy savings of up to 60% compared to traditional approaches. Beyond energy efficiency, these strategies also enhanced user comfort in leisure environments by reducing condensation and mould, and by smoothing transitions between wet and dry areas such as from the pool to the changing rooms where temperature and air quality often vary sharply.”
“Partnerships and collaboration have been the cornerstone of this project’s success. Working with Gale & Snowden was a valuable learning process, which allowed both of our practices to expand our knowledge and best practice within sport, leisure and community design. Willmott Dixon and the wider project team worked hard to improve the total embodied carbon levels, including a bespoke hybrid cross-laminated timber (CLT) structure designed by Engenuiti – and a low-carbon Myrtha Pools tank.”
For further information, please visit www.gt3architects.com
