ASHRAE Publishes Air Diffuser Designer's Guide

A new Designer's Guide to Ceiling-Based Air Diffusion, published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), assists engineers and designers in the creation of effective HVAC systems. The guide applies primarily to conventional ceiling-based air diffusion equipment, which is prevalent in most new commercial and institutional buildings in the U.S. There are several methods for selecting ceiling-based products, notes Brian Rock, Ph.D., P.E., co-author of the guide. "However, due to time pressures in design firms and sometimes a lack of mentoring of new HVAC designers, these selection methods may not be fully used," Rock says. "Instead, too-generalized rules of thumb are frequently used." While these rules may work well, problems with thermal comfort, indoor air quality (IAQ) or noise may occur in some cases. The guide assists designers in reexamining their air diffusion design techniques, Rock adds. The guide addresses thermal comfort, IAQ, sound, behavior of ideal air jets, room air diffusion, air outlets, and inlets and design methods and provides examples. The cost of the Designer's Guide to Ceiling-Based Air Diffusion is $89 ($71, ASHRAE members). To order, contact ASHRAE Customer Service at 800-527-4723 or visit

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