An IPS-calibrated Outdoor Air Flow Control Strategy in Multizone Commercial Space

Building ventilation systems are equipped to improve indoor air quality (IAQ) through bringing in the non-polluted outdoor air for occupants. Carbon dioxide (CO2) concertation level serves as one of the most critical indicators for IAQ and occupancy to control ventilation systems. Many control strategies (such as ASHRAE standard 62.1) utilize CO2 concertation to determine the necessarily supplied air amount in building space. However, many studies suggest that due to the CO2's mixed dual functions in indicating IAQ and occupancy, a large discrepancy is observed between the CO2 estimated occupancy and actual occupancy, especially in space with multiple zones. These estimation errors not only result in inefficient control response but also wasted fan power in unoccupied space. To solve those problems, this study utilized indoor positioning system (IPS) to detect occupancy and select the critical zones. The proposed control strategy calibrates the outdoor air flow based on detected zone occupancy. To validate the proposed strategy, this study compared the outcomes with conventional pure CO2 based control strategy. The simulation results suggest the proposed method could achieve acceptable CO2 concentration under 1000ppm for most zones and over 25% energy saving from primary fans and cooling coil during a sample weekday and a sample weekend day.