Fan energy consumption in variable air volume (VAV) systems is affected by both the technique used to control the flow rate and the control algorithm used. In this paper a simulation study is made of a "standard" 10,000 square foot building. Three flow-control techniques -- system dampers, inlet vane control, and variable speed control -- are considered along with two types of control algorithms: proportional (P) and proportional-integral (PI). A relationship is derived for the relative power consumption under P and PI control. Fan power consumption in the example building is calculated for five locations, two types of fan (backward-inclined centrifugal and vaneaxial), the three control techniques, and the two control algorithms. Significant differences are found in annual energy consumption for the different cases.

Units: I-P