Challenge
Founded over 450 years ago, Highgate is one of the UK’s leading independent school, embarked on a major redevelopment and refurbishment of its Mallinson Sports Centre, which was an ageing 1960s facility comprising a 25metre swimming pool, multi-use sports halls, and associated support spaces.
The project presented a set of complex and highly sensitive challenges as the school required a modern, efficient, and sustainable building services upgrade, but the works had to be carried out within the constraints of a heritage structure, extremely limited spatial allowances, and a live operational environment.
Adding to the challenges, there were no original, complete or update CAD drawings available, which meant PDA had to begin by reverse-engineering accurate 3D models of the building infrastructure. Compounding this were tight ceiling voids, legacy systems with minimal as-built records, and the necessity of staging works exclusively during school holidays to avoid disruption to term-time activities. The plantrooms were undersized, the services aging, and the school’s broader aim of long-term carbon reduction demanded a complete rethink of energy strategy all while preserving the architectural character of a much-valued building.
Overview
PDA was appointed to lead the full mechanical and electrical (M&E) design across a four-year phased programme. Our role extended far beyond conventional HVAC upgrades. From the outset, we worked in close collaboration with the school’s estate team and project architects to design and deliver a bespoke solution that balanced technical performance, spatial constraints, and aesthetic sensitivity.
We engineered and implemented a complete climate control strategy tailored to pool environments. This included high efficiency condensing boilers, smart air handling units with integrated BMS (Building Management System), and a carefully calibrated heat recovery system using tailored plate heat exchangers. Fresh air intake was optimised and conditioned through recovery cycles, maximising thermal efficiency while maintaining internal comfort levels and strict humidity control. CFD (Computational Fluid Dynamics) modelling was employed throughout to fine-tune airflows and eliminate cold spots particularly around the pool surround where user comfort is most vulnerable.
Solution
PDA’s approach placed innovation at the core of every solution. Starting with comprehensive on-site surveys, we laser-scanned and rebuilt the infrastructure layout in digital form. From this, we could run airflow simulations and model system zoning, enabling us to custom design and fit modern services into tight spaces that would typically restrict plant functionality.
The installation of a condensing boiler plant paired with plate heat exchangers allowed us to reclaim thermal energy from extracted air and redirect it toward pre-heating incoming air and pool spaces, thus reducing total energy demand and carbon footprint whilst maintaining stable temperature and humidity levels.
Four low-NOx gas boilers (165 kW each) were installed in Phase 1 to supply pool, changing rooms, and domestic hot water, consuming approximately 45,684 kWh annually with NOx emissions capped at 35 mg/kWh (well within Camden Council approval thresholds). Boilers were intentionally relocated to optimise plantroom utility and align with compact space design. Operating at a thermal delta of 65 °C flow / 30 °C return, the configuration delivers maximum heating potential while safeguarding newly designed heat recovery circuits.
A centralised BMS gave the estate team full oversight of real-time conditions, from CO₂ and humidity to fan speeds and heating loads.
In spaces where original architecture could not be altered, we designed concealed duct runs, wall-mounted service trays, and access panels that respected listed features. Acoustic dampening measures were embedded at design stage to ensure that ventilation systems operated quietly and discreetly within designated zones including climatological safeguards.
Benefits
The result is a modern M&E system that quietly supports the day-to-day activities which has reported a significant reduction in heating energy costs estimated at over 30% thanks to the efficiency gains introduced by the new systems. Air quality and thermal stability in the pool and sports halls have improved measurably, contributing to a healthier, more comfortable environment for students, staff, and visiting users.
Maintenance access has been dramatically improved, with critical systems now easier to monitor, service, and adjust through digital interfaces. Most importantly, the phased delivery meant that not a single lesson, sports fixture, or external hire was impacted throughout the entire programme. The works were invisible to most users—yet the benefits are now felt every day.
This project has also made a material contribution to the school’s broader sustainability goals, aligning with estate-wide carbon reduction plans and providing a replicable model for other educational or community swimming facilities.
Recommendations
Highgate School’s project offers important insights for any live environment refurbishment, especially in education, healthcare, and leisure sectors where climate control, energy efficiency, and operational continuity are paramount.
We recommend that project teams prioritise early-stage airflow modelling, particularly when comfort, sustainability, and heritage constraints intersect. Systems such as plate heat exchangers, when correctly integrated, they offer excellent payback periods and long-term energy resilience.
For PDA, performance modelling is a vital part of verifying the real-world performance of a design before any installation and as part of all our projects M&E engineering we undertake this ethos through EPC evaluation as best value practise.
Ultimately, this project demonstrated that it is entirely possible to deliver modern environmental engineering within sensitive, operational, and heritage contexts
without compromise. With our experienced team, the right modelling tools, and the right intent, energy performance and user comfort can go hand in hand.
If your project demands high-performance engineering in a live or constrained environment, whether that’s a school, heritage property, or community asset talk to PDA. We bring engineering passion, precision, and partnership to every project, and we take pride in delivering bespoke solutions that clients trust, value, and return to.
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