PNNL

Abstract

Variable-air-volume (VAV) systems are used in many office buildings. The terminal’s minimum air flowrate set point is an important parameter that has significant impact on energy consumption and indoor air quality. Conventional controls usually have the terminal’s minimum air flowrate at a constant, irrespective of the occupancy status. Such practice may cause energy waste, ventilation and thermal comfort problems. This paper examines the potential of energy savings by occupancy-based controls (OBCs). The sensed occupancy information, either presence or the people count, is used to determine the air flowrate of terminal boxes, the thermostat set points, and the lighting as well. Using EnergyPlus, energy savings of OBC strategies are evaluated for representative existing medium office buildings in the U.S. Simulation results show that for the location of Baltimore, MD, the use of air-side economizer or not does indeed have significant impact on the comparison between the two OBC strategies. The OBC based on the occupant presence has about 13% whole-building energy savings no matter whether the air-side economizer is used in the AHU operation. However, for the OBC based on the people count, the percentage of energy savings increases from 13% for the case of not using air-side economizer to 23% for the case of using air-side economizer.