What formula do you use to determine the airflow in an HVAC system?

The formula for determining airflow in an HVAC system is derived from the relationship between velocity and area. Airflow, expressed in cubic feet per minute (CFM), is calculated by multiplying the velocity of the air (in feet per minute, or FPM) by the cross-sectional area of the ductwork or opening (in square feet). This relationship is based on the principle that the amount of air flowing through a space depends on how fast the air is moving and how much space it has to flow through.

In simple terms, if you know how quickly the air is traveling (the velocity) and how large the passage is (the area), you can calculate the total volume of air moving through that section in one minute. Understanding this formula is crucial in designing and balancing HVAC systems to ensure the right amount of airflow is delivered to various areas of a building, impacting heating, cooling, and ventilation efficiency.

The other options do not reflect the correct relationship needed to compute airflow in an HVAC context. For example, dividing area by velocity would not yield airflow, nor would adding velocity to area provide a meaningful airflow measurement. Using pressure in a formula for airflow is also not applicable as it does not denote the relationship required for calculating volumetric flow rate.