ASHRAE 90339 2011 Edition, January 1, 2011
A Practical Guide to Noise and Vibration Control for HVAC Systems
Over the past few decades, building design teams have become more aware of the potential noise and vibration problems from HVAC systems. Mechanical engineers are specifying sound traps (duct silencers), acoustical louvers, sound-absorbing duct liners, and vibration isolators, while architects are designing mechanical room walls and slabs with high sound transmission class (STC) ratings. Despite the addition of these noise and vibration control features in more and more building designs, complaints of excessive HVAC system noise and vibration are still common. Investigations into these complaints by acoustical professionals have found that, in many cases, the correct equipment and materials were used, but they were not properly integrated into a quiet system, or some seemingly insignificant detail was omitted that negated the expected acoustical benefit.