The HVAC component of the baseline audit will most likely be the lengthiest and addresses:

The mixing plenum and dampers in AHUs
Filters
Cooling coils and condensate pans in AHUs
Mechanical room
Air ducts and air plenums
Diffusers, grilles, and registers
Fans and fan chambers
Exhaust fans in special-use areas
Terminal boxes
Fan coil unit, unit ventilator and induction units
Boiler
Chiller
Condensing equipment (cooling tower)
Elevator and stairwells
Air compressor and pneumatic system.