LV-22-C033 - Field and Simulation Testing and Improvement of ASHRAE Guideline 36 Duct Static Pressure Resetting Algorithm

ASHRAE High-Performance Sequence of Operation Guideline 36 recommends resetting the duct static pressure set point in VAV systems using the trim and respond algorithm to save fan energy and ensure every VAV box can provide the required airflow rate to meet the zone load. This paper provides field studies to test the Guideline 36 duct static resetting algorithm and measure its performance under various conditions in fully instrumented VAV systems located in the HVAC lab at the University of Cincinnati and proposes improvements using trim and respond boosters to improve the fan responses to track VAV box airflow needs. Multiple tests were conducted on two DX and chilled-water VAV systems that serve three controlled zones with hot-water reheat VAV boxes controlled by a typical commercial BACnet web-based building automation system BAS. The performances of various components such fan, duct static pressure, and VAV boxes were measured under different testing conditions. The simulation studies using the building energy simulation software EnergyPlus were also conducted to extrapolate each component performance under various locations and for a longer period of time. The field and simulation results show that the modified resetting algorithm can improve the performance of VAV boxes by reducing the time of being starved and at the same time ensure that the fan energy saving is obtained.