Gain scheduling based ventilation control with varying periodic indoor air quality (IAQ) dynamics for healthy IAQ and energy savings

Abstract The subway is a popular mode of transportation during the morning and evening rush hours. At these times, an underground subway station generates a high concentration of air pollutants and affects the dynamics of indoor air quality (IAQ) differently compared to other normal operation times. This study proposes a new ventilation control system targeting the varying IAQ dynamics by using a gain scheduling method. The gain-scheduled ventilation control system is implemented at a D-subway station and consists of one feedback and two feedforward controllers that manipulate ventilation inverter frequency. These controllers were able to reject the effect of the train schedule and the effect of the outdoor air quality (OAQ). The feedback controller of the gain scheduling method was tuned by ZN, IMC, and ITAE-1 tuning rules for the three different operating time zones (morning rush hour, evening rush hour and ordinary time zone), and the ventilation control performances are compared. The results show that the proposed gain-scheduled ventilation control system saved 4% of the ventilation energy compared to the manual ventilation system while maintaining a comfortable IAQ under 120 μg/m 3 .