Evaluation of the Impact of Minimum Airflow on the Energy Consumption of Single Duct VAV Terminal Boxes

Abstract

Terminal boxes are critical components of variable air volume (VAV) systems. The minimum airflow of terminal boxes is a key factor for comfort, indoor air quality (IAQ) and energy cost. If the minimum airflow is higher than needed, terminal boxes will have significantly more simultaneous heating and cooling, and airhandling units (AHUs) will consume more fan power. Buildings will have IAQ problems if the minimum airflow is less than required. A dynamic building simulation and field experiment were carried out to evaluate the impact of minimum airflow on the energy consumption of single duct VAV terminal boxes. A comparison of the simulation data with the existing constant setpoint revealed 20% annual energy savings in the improved minimum airflow setpoint. The experiment showed that the room air temperature can be maintained stably and the vertical difference in the room air temperature is lower than the comfort value when the improved minimum airflow setpoint is applied. Measurements of the CO 2 levels also revealed no indoor air quality problems.