ASHRAE is providing guidance on designing underfloor air distribution systems via its Underfloor Air Distribution Design Guide, written by to Fred Bauman, P.E. Originally introduced in the 1950s in spaces having high heat loads, such as computer rooms, underfloor air distribution (UFAD) has proven to be the most effective method for delivering conditioned air to localized diffusers in the occupied zone of a building. While use of UFAD is increasing, most buildings continue to use overhead air distribution systems that produce a single uniform thermal and ventilation environment within each building zone. This offers little chance of satisfying the environmental needs and preferences of individual occupants, according to Bauman, research specialist with the Center for the Built Environment, University of California, Berkeley. To order, contact ASHRAE Customer Service at 800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 404-321-5478, by mail at 1791 Tullie Circle NE, Atlanta, GA 30329, or visit