BREAKING NEW GROUND: HOW B&K HYBRID SOLUTIONS HAVE HELPED DELIVER THE UK’S LARGEST PASSIVHAUS LEISURE CENTRE

The brief for Eclipse Leisure Centre was unprecedented: create the UK’s largest 50/50 wet and dry leisure centre designed to Passivhaus standards, while meeting strict budget constraints and sustainability targets. Located in Staines-upon-Thames, the £50m project needed to consume 60-70% less energy than conventional leisure facilities – a significant challenge in a sector notorious for high energy consumption and comfort issues. Now one of the world’s most advanced leisure facilities, B&K Hybrid Solutions’ specialised expertise in hybrid timber construction was key to the project’s success.

Now open to the public, Eclipse Leisure Centre offers a comprehensive range of facilities, including an eight-lane 25m main pool and 20mx10m learner pool with a movable floor, a 6-court sports hall and 950sqm of fitness space.  The facility also features a flagship rooftop with four artificial football pitches, an open-plan café area, and a feature staircase, to create a welcoming biophilic entrance.

The project team selected a hybrid material solution that balanced aesthetics, performance and sustainability, exceeding a single system approach. The design required innovative engineering solutions to overcome complex structural, acoustic, and moisture management challenges, particularly in high-humidity environments like the pool hall.

While timber was primarily specified for aesthetic reasons, with significant areas left exposed, this evolved into a hybrid timber-steel approach to maximise the benefits of each individual system: timber’s visual warmth, carbon sequestration properties and prefabrication benefits were expertly balanced with steel’s excellent structural performance.

B&K Hybrid Solutions were selected for their proven expertise in hybrid timber-steel construction, where their understanding of engineered timber’s behaviour in challenging environments proved crucial. Working alongside GT3 Architects, structural engineer Engenuiti, and main contractor Willmott Dixon, BKHS’s technical knowledge helped to deliver timber applications in areas typically dominated by concrete, including the lift cores, pool hall, and spectator seating. A cost analysis completed by Willmott Dixon also confirmed that a hybrid timber-steel solution could meet the council’s budget, without sacrificing the desired aesthetic or performance requirements.

BKHS delivered over 2,195m³ of precision-manufactured, PEFC-certified engineered timber, comprising 127m³ of glulam and 2,067m³ of Stora Enso Cross Laminated Timber (CLT). Critical to the project’s success was BKHS’ rigorous moisture management strategy. Regular moisture readings were taken throughout the construction phase, with comprehensive procedures such as the application of end grain sealant and removal of standing water ensuring timber integrity. All joints were meticulously sealed to achieve Passivhaus levels of airtightness, which are 95% better than standard building regulations.

The visual-grade timber panels eliminated the need for additional finishes, reducing both material use and long-term maintenance requirements. Factory-controlled manufacturing ensured consistent quality and precise tolerances, while pre-installed lifting devices and protective treatments accelerated on site installation.

“The hybrid combination of timber and steel, as offsite manufactured products, ensured Eclipse was delivered on time and to budget, setting a new standard for hybrid leisure centres of the future,” Alex Brock at BKHS comments. “The solution also enabled remarkable performance achievements in both airtightness and energy efficiency. The timber structure sequestered 1,668 tonnes of CO₂e, while a whole-life carbon assessment showed a 12.97% reduction in embodied carbon compared to a composite steel alternative. The building achieves airtightness of 0.4 m³/hr/m² at 50pa and targets operational energy consumption of just 120 kWh/m²/year.”

BKHS’ ‘build-less’ approach, utilising lightweight timber, enabled shallow spread foundations instead of piles, further reducing steel, concrete, and excavation requirements. The prefabricated elements arrived ready for rapid installation, minimising site disruption and accelerating the construction programme. Eclipse Leisure Centre now stands as a benchmark for sustainable leisure facility design, demonstrating that complex, high humidity building types can achieve Passivhaus standards.

Daniel Mouawad, Chief Executive of Spelthorne Borough Council, said: “We are delighted to be a pioneering authority, demonstrating our commitment to net zero by building an ultra-low Passivhaus leisure centre. Having declared a climate emergency, we recognise the need to lead by example to achieve cleaner and greener lifestyles and a sustainable borough for all to enjoy. This centre is a great example of partnership working and will provide the right infrastructure to meet our communities’ changing needs and will enable residents to stay active in a healthy environment, with low chemical pools and a dementia friendly design.”

BKHS’ extensive experience and hands-on involvement were instrumental to the success of this project, ensuring that every stage, from early coordination to final handover, was delivered to the highest standard. The ability to adapt to evolving requirements, manage complex MEP systems, and collaborate seamlessly with multiple stakeholders made a tangible difference to the build quality, efficiency, and long-term sustainability of the leisure centre. For clients seeking a trusted, forward-thinking partner on future leisure developments, BKHS offers the technical capability, collaborative approach, and proven track record to deliver outstanding results.

For more information visit: www.bkhybridsolutions.co.uk or contact sales@bkhybridsolutions.co.uk