When you have to individually go verify whether 128 air curtains meant to ensure air balance in the original design’s branch ductwork are still there or not, you’re not having an easy time of it.
One of the worst-performing buildings I’ve had the pleasure to study was a 375,000-sq-ft laboratory building at a Midwest university.
The HVAC system consisted of twelve central station AHUs manifolded together to supply 26 risers that eventually went up several different building cores and fed reheat coils on the various floors. The exhaust systems were split out among 126 centrifugal exhaust fans located in penthouses centered above each of the building cores. The system was originally designed with constant volume reheat coils with constant volume fume hood and general exhaust.