Underfloor air or ceiling-air plenum are common systems for allowing occupant comfort control. In addition, they can: 

allow for flexibility in layout and design, and ease of electrical wiring, installation of work stations, and arrangement of work spaces; 
realize first-cost savings in reduced duct work, lower floor height and possible an additional floor with more leasable space;
and enhance daylighting by creating higher floor-to-ceiling heights.