ATLANTA - The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has published Underfloor Air Distribution Design Guide, written by Fred Bauman, P.E., a research specialist with the Center for the Built Environment, University of California, Berkeley. Underfloor air distribution (UFAD) systems use the open space between a structural slab and the underside of a raised floor system to deliver conditioned air to supply outlets located at or near floor level within the occupied zone of the space.

Originally introduced in the 1950s in spaces having high heat loads, such as computer rooms, UFAD has proven to be the most effective method for delivering conditioned air to localized diffusers in the occupied zone of a building, stated Bauman.

According to ASHRAE, while the use of UFAD is increasing, most buildings continue to use overhead air distribution systems.