Performance Study of an Under-floor Air Distribution System in an Education Building to Identify Building Energy Efficiency Improvement Opportunities

The HVAC system accounts for 30 to 50 percent of a typical building's energy consumption; in hot and humid climates it is closer to the upper end of that range. Implementing effective energy saving measures for the building HVAC system can reduce the building energy consumption, reduce peak demand, and improve building comfort. In recent years, under-floor air distribution system (UFADS) is used as an innovative approach to HVAC system to offer utmost in occupant comfort, improved indoor air quality and energy savings. In this study, the operation and performance of a UFAD system in an education building located in a hot and humid area is evaluated. The study found the building was overcooled and the UFAD system was in reheat mode even in hot summer. Optimizing existing air handling unit (AHU) discharge air temperature (DAT) set point reset based on building load and reducing under-floor plenum static pressure in half are recommended to improve building comfort and energy performance. It is estimated that implementing the optimized AHU DAT set point reset schedule can potentially reduce about 30% of the UFAD system thermal decay. The reduction of the under-floor plenum static pressure in half can potentially reduce the system minimum airflow rate by about 30 %.