ATLANTA - The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has publishedUnderfloor 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.

"As a result, thermal comfort and indoor air quality continue to be two of the primary concerns among workers," Bauman said.

The guide was developed through research funded by ASHRAE and the Center for the Built Environment at the University of California, Berkley. For more information, visit

Publication date: 12/22/2003