In Revit, a zone is considered an HVAC system. A number of “like" spaces (same orientation, all internal, all offices, etc.) are assigned to a zone, and the zone is served by one piece of HVAC equipment whether it is a VAV box or rooftop unit. The zone data object in Revit is assigned all of the spaces it contains, and it also contains its own properties that are unique to HVAC systems. These properties include: