HVAC scope covers heating, ventilation, and air conditioning work, equipment, ductwork, piping, controls, and everything required to condition and move air through a building. On most commercial projects, it’s one of the largest and most spatially demanding trade scopes, competing directly with other systems for the same limited ceiling and shaft space.
Ductwork’s physical size is really what drives so much of the coordination attention HVAC scope receives. A large supply trunk can easily be two or three feet in one dimension, and unlike smaller conduit or piping that can often be rerouted around an obstruction with relative ease, a duct that size has real limits on how much it can be reshaped or relocated before it stops performing to its designed airflow capacity—which means HVAC routing tends to get locked in relatively early in the coordination sequence, and other trades often have to route around it rather than the reverse.
Equipment selection and scheduling carry their own coordination weight beyond just ductwork routing. Rooftop units, air handlers, and chillers have long lead times for procurement, and their dimensions, clearance requirements, and large size mean that the final design must be completed early to allow for the other trades to work around the final equipment size.
HVAC cross-trade issues are most pronounced in ceiling spaces and mechanical rooms. In ceiling spaces, electrical, mechanical, plumbing, and fire protection trades all vie for the same space, and in mechanical rooms, the large equipment and piping clearance requirements make otherwise simple equipment maintenance a complex effort.
The performance of HVAC systems is truly validated and tested during the commissioning process. A system that appears complete may still fail to meet the system’s designed airflow and temperature control due to the absence of balancing or controls programming, or due to the absence of the sequencing and testing of the control system. A shortened project timeline often results in insufficient time for system commissioning and therefore defensible system comfort and performance.
An important tip for new HVAC drawing reviewers: remember to check the mechanical schedule sheet along with the plan views, as unit capacities, electrical needs, and even physical dimensions are generally listed on the schedule and not on many of the plan sheets. Most information, if not all, will be missing if the schedule is not included.
