Outdoor commercial pools are often about 25m long x 5 or 6m wide and they will require at least two large filters of about 2m in diameter. The rest of the equipment does not take up much more space than a domestic outdoor pool and so a typical outdoor pool plant room will need to be about 8m long x 5m wide.
Indoor commercial pools also need large filters and even larger AHU's. As a result most commercial indoor plant rooms will require any area that is equivalent to 40 to 50% of the pool area.
An undercroft is a vital ingredient of every indoor commercial pool together with the Air Handling system and adequate space for the ducting must be provided as a pressurised undercroft is unlikely to be satisfactory in a commericial pool.