What is the formula for determining energy loss in ducts?

The formula for determining energy loss in ducts is best represented by the relationship that includes the length of the duct and the friction loss per unit length. In this context, as air moves through a duct system, it encounters resistance due to friction along the duct surfaces. This friction generates a loss of energy in the system, which is critical for HVAC professionals to account for when designing and evaluating ductwork.

The concept of friction loss is typically presented in terms of a specific value, often measured in units like inches of water column per 100 feet of duct. Therefore, by multiplying the total length of the duct by the friction loss per unit length, one can effectively calculate the total energy loss due to friction over that distance. This calculation is vital for ensuring efficient airflow, comfort, and energy efficiency in an HVAC system.

Other options do not align with the calculation of energy loss in ducts. For instance, focusing solely on air density, area, or velocity does not account for the frictional factors that significantly impact energy loss in duct systems.