Underfloor air distribution: thermal stratification

Abstract

More than 130 underfloor air distribution (UFAD) systems are installed in North America today, and that number is growing. In comparison to classical displacement ventilation (DV) systems that deliver air at low velocities, typical UFAD systems deliver air through floor diffusers with higher supply air velocities. Ina addition to increasing the amount of mixing (and therefore potentially diminishing the ventilation performance compared to DV systems), these more powerful supply air conditions can have significant impacts on room air stratification and thermal comfort in the occupied zone.