HVAC controls for a combined school and swimming pool complex

The brief

A school with an attached swimming pool had one plant room serving two environments that want opposite things. The pool hall needs humidity control and a positive-to-negative pressure relationship with the rest of the building; classrooms need air quality control on an intermittent occupancy pattern. The installation window was a single summer holiday.

What we did

We designed the two strategies as explicitly separate control domains sharing a plant room, with the interface between them drawn and interlocked rather than assumed. The pool hall runs dehumidification with a fixed pressure relationship holding chlorinated air inside the hall. Classrooms run CO₂-based demand control with a scheduled occupancy baseline.

Delivery notes

The programme drove the delivery structure. With one summer to install, panel manufacture had to start before the full design was complete, so we issued the panel schematics and I/O schedules as a first package in week four, and the field layouts and commissioning documentation as a second package in week eight.

The corridor between the pool hall and the school block turned out to be the real design problem — it is where the two pressure regimes meet. It got its own interlocked control zone and its own section on the drawings.