Air Balancing is a process that ensures the HVAC system design, as designed, has successfully been created in the real world. It is the norm in commercial construction; rare in residential construction.
Commercial Air Balancing
In commercial construction, Mechanical Engineers design HVAC
systems and specify ...
Air flow in cubic feet per minute (CFM) from each ceiling grill
Ventilation air flow
Exhaust fan air flow
Motor amp draw
Temperatures into and out of conditioning equipment
Pressure differences between areas
Testing and balancing assures design specifications are met.
Residential Air Balancing
In most new homes, none of this design work is done.
But, good HVAC contractors rely on a Manual J Load Calculation to determine the tonnage of equipment for your specific home and the volume of air (CFM) each room should get.
Room air flow is seldom measured to see if each room is getting the design air flow. This is why some of your rooms are too cold and some to hot.
This can be rectified by balancing the flow.