Each method of airflow control imposes an energy loss burden or energy losses. You can manage the energy wastage by the proper choice of airflow control.
The effects are different for each airflow control as seen in the figure.
Compare the power savings of using VSD to drive six (6) 1kW fans. The fans feed into identical systems of duct work and fixtures.
Calculate the power requirement if the airflow is halved (1/2) using either system.
Fan and system curves to show the
different flow controls