A study on the control method of single duct VAV terminal unit through the determination of proper minimum air flow

• An air flow increase model and outdoor air intake rate increase model were proposed.
• Control algorithms with proper minimum airflow for a single duct VAV terminal unit were developed.
• Proposed control algorithm was compared to IAQ, stratification and energy consumption.

The objective of this study was proposed a control method for the minimum air flow rate of a VAV terminal unit at an office building. The minimum air flow rate of the VAV terminal unit is the key factor affecting the thermal comfort, indoor air quality (IAQ), stratification and energy consumption, depending on the operating mode of the VAV system. Therefore, selecting the proper minimum air flow is very important. In this study, an algorithm was proposed considering the IAQ and stratification. The vertical air temperature was analyzed to find the supply air temperature that did not cause stratification. The integrated control algorithm with an air flow increase model in the VAV terminal unit and outdoor air intake rate increase model in the AHU was developed by comparing the energy consumption. Finally, the existing and proposed control algorithms were compared through a simulation. The proposed method was found to be more effective than the existing control method. The proposed VAV terminal unit control method satisfies all the conditions of indoor thermal comfort, IAQ and stratification issue. As a result of the energy comparison with the existing control method, the method satisfies not only the indoor thermal comfort, IAQ and stratification issue, but also reduces the energy consumption.