Traditional “mixing” ventilation cooling systems use turbulent jets of fresh air that mix with and dilute any stale air. In contrast, displacement ventilation (DV) cooling uses a lowvelocity (0.15 to 0.2 m/s [30 to 39 fpm])1 stream of more moderately cooled air introduced via diffusers located either in walls at floor level or through a raised floor (Figure 1). The cooler, slowmoving air slowly spreads over the floor and displaces the warmer, stale air toward the ceiling, where it leaves the room.