An electronic equipment enclosure comprises a frame structure formed from a plurality of support posts and at least partially enclosed by a plurality of panels. The panels include at least side, top and back panels defining an enclosure having a top, a bottom and a rear thereof. The top panel includes an opening there through that is rectangular in shape. The equipment enclosure further comprises an exhaust air duct extending upward from the top panel of the enclosure. The exhaust air duct is rectangular in cross-section and is disposed in surrounding relation to, and in fluid communication with, the top panel opening. The exhaust air duct is adapted to segregate hot air being exhausted from the enclosure from cool air entering the enclosure, thereby improving thermal management of the enclosure.