Building occupants complain about too much heat, too much cold, or too much noise. When HVAC systems are running at a comfortable, quiet level, nobody thinks about them.
“Occupants aren’t like engineers who specialize in this,” says Erik Miller-Klein, P.E., SSA Acoustics, LLP, Seattle, WA. “They’re not wondering how energy efficient the system is or how the variable frequency drives are running or how sustainable the building is. The two metrics that occupants are concerned with are thermal comfort and noise.”
The question of why a space is quiet or noisy will be examined in a free ASHRAE session held as part of its 2013 Winter Conference.
The AHR Expo Session, “Basics of HVAC Noise Control,” takes place from 2:00-3:30 PM on Tuesday, Jan. 29, in Room C147 of the Dallas Convention Center. ASHRAE Conference registration is not required to attend and no badge is needed.
“Designing HVAC systems with good acoustic performance can be a challenge,” Miller-Klein says. “This session addresses three common issues to improve acumen for sound and vibration, including the idiosyncrasies of selecting fans that optimize acoustic and energy performance for improved system design and the physics of sound that explains the performance and limitations of silencers and acoustic louvers.”
The session also will allow attendees to fine tune the most valuable and effective tool for acoustics — their ears — by providing audio examples to connect them with the fundamental aural experience.
Presentations and speakers are:
• Fan Selection Impact on Noise, Mark E. Schaffer, P.E., Schaffer Acoustics Inc., Pacific Palisades, Calif. The noise produced by a fan depends not only on its duty point but also on its type and size. For a given duty point a fan that is the wrong type and/or the wrong size can be as much as 30 dB louder than the optimum selection. This presentation will show examples of quiet and noisy fan selections and offer simple guidelines for selecting fans to minimize excessive fan noise.
• Understanding the Physics of Silencers , Dan LaForgia, Industrial Acoustics, Bronx, N.Y. HVAC silencers or sound attenuators are used on many different types of HVAC equipment. Silencer manufacturers have various models designed to meet specific dynamic insertion loss and static pressure drop requirements. A properly selected silencer can reduce noise levels significantly across the entire frequency spectrum. However, if a silencer is improperly selected, issues in acoustic performance, pressure drop and self-noise may arise. The silencer itself may even become another noise source! This presentation will explain silencer definitions, testing procedures and how to properly select silencers to ensure the maximum performance is gained without disrupting the HVAC system.
• What Does That Sound Like and Mean? (Ear Training), Erik Miller-Klein, P.E., SSA Acoustics, LLP, Seattle, Wash. Understanding how noise can be an annoyance and what the goal criteria sounds like gives you, the designer and contractor the tools to be successful on the acoustic front. Explore the aural landscape of HVAC acoustics with your ears as we navigate successful projects and common issues and how to troubleshoot problems.