Modeling and analysis of an air handling unit to improve energy efficiency

Abstract

The Air Handling Unit (AHU), which serves the entire basement of Engineering and Technology (ET) building on IUPUI campus, had constant set points of discharge air temperature and supply air static pressure. Two reset schedules were investigated to determine which was the best control strategy to minimize energy consumption of the AHU. In this research, a gray box model was established to create the baseline of energy consumption with constant set points and predict the energy savings using two di↵erent reset schedules. The mathematical model was developed in Engineering Equation Solver (EES). It was validated using two sets of sub hourly real time data. The model performance was evaluated employing Mean Absolute Percentage Error (MAPE) and Root Mean Square Deviation (RMSD). Additionally, uncertainty propagation identified outside air temperature, supply airflow rate and return air temperature were the key parameters that had an impact in overall energy consumption. Discharge air temperature was reset based on return air temperature (RA-T) with a linear reset schedule from March 4 to March 7. Static pressure was reset based on the widest open Variable Air Volume (VAV) box damper from March 20 to March 23. Results indicated that 17% energy savings was achieved using discharge air temperature reset while the energy consumption reduced by 7% using static pressure reset.