Dedicated outdoor air systems (DOAS) are often thought to be inferior to all air systems when contaminant flushing rates from occupied spaces are considered. This is a particularly prevalent attitude when the parallel terminal sensible cooling equipment provides no, or minimal, filtration of terminal air, such as the case with chilled ceilings, beams, and even fan coil units. The central thrust of this paper is to determine if the attitude concerning the perceived inferiority of DOAS’s contaminant flushing rate is warranted. The investigation is carried out via an analytical case study involving a multi zone facility served by either a DOAS or a Variable Air Volume (VAV) system.

Units: Dual