A method to generate effective cooling load factors for stratified air distribution systems using a floor-level air supply

A vertical temperature gradient is known to occur in an enclosure that is ventilated by stratified air distribution (STRAD) methods. Thermal stratification offers distinct energy-saving possibilities. For example, a portion of heat gains can be excluded when calculating the air supply rate and the air-conditioning load. The cooling load reduction of a heat source depends primarily on its vertical location and radiant and convective split. In this study, an effective cooling load factor (ECLF) was defined to calculate the effective heat gains, which can be used by design engineers for the determination of the reduced-supply airflow rate and reduced cooling coil loads for common- and split-return/exhaust configurations with STRAD. Numerical simulations used to obtain these factors for various internal heat sources in a small office were presented, and on-site measurements were carried out to validate the performance of computational fluid dynamics in predicting the thermal stratification in large spaces. A fully developed database of ECLFs will be very useful when designing such systems.