Annual energy use of series and parallel fan powered terminal units.

Abstract

Traditional mass and energy balance component models of fixed and variable airflow series and parallel fan powered terminal units (FPTUs) were used to estimate the annual energy use in a small office building with hourly loads for five cities generated from EnergyPlus. Fixed airflow series and parallel fan powered terminal units with permanent split capacitor motors were assumed to be the baseline in each city. All variable airflow FPTUs utilized electronically commutated motors. Sizing effects of the variable airflow FPTUs were evaluated by examining the use of the capacity factors. Variable airflow series units showed 10% reduction in total energy use compared to fixed airflow series FPTUs. Variable airflow parallel FPTUs showed little energy savings compared to their fixed airflow counterparts. Energy analysis was also performed on two approaches for controlling the cooling operations of variable airflow series units and impact of leakage on the performance of parallel FPTUs.