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In addition to keeping building occupants feeling comfortable, large, powerful HVAC systems can easily create noise inside and outside of a building. This persistent low-frequency noise can actually cause health issues. Increased stress, mental health and cognition problems, cardiovascular risk, sleep disruption and more are all possible side effects of unwanted noise, according to Harvard Medicine magazine.
There are two types of HVAC noise:
Each type of HVAC noise must be treated differently, and some acoustic HVAC treatments can even help with thermal insulation.
Airborne noise travelling through the supply and return duct system can be mitigated by HVAC sound attenuators (also known as silencers) and acoustic louvers.
HVAC silencers are available in custom configurations or in standard rectangular sizes. They mitigate sound when installed directly in the ducted air path.
Silencers can reduce noise using a variety of techniques, such as perforated metal baffles filled with a sound-absorbing material, acoustic bullets filled with absorptive material, lined acoustical fills, and packless designs for environments that must remain as sterile as possible.
Take the following packless HVAC silencer as an example. Packless silencers contain no fill or acoustical media, and are easy to clean and drain.
The first key features are the multiple resonant chambers located behind the curving metal as seen in the front view of the silencer. Inside the HVAC silencer, there are many small perforations, which open into the resonant chambers. As the sound pressure waves travel through the system, they lose energy by spreading through the perforations and into the resonant chambers. This motion of the sound waves is somewhat reminiscent of the way sound moves in Helmholtz resonators.
Acoustic louvers are as critical for maintaining airflow as they are for managing noise levels. These louvers act as a noise barrier without reducing the system’s capacity for air, and rely on maximizing surface area instead of taking up a lot of space. The tops of each louver blade are solid, and the underside is perforated. Inside each of the individual louvers, there is absorptive material to combat the sound pressure waves.
For breakout noise that travels through the walls of the ductwork, the name of the game is isolation. Lagging designed to wrap pipes and ducts enhances sound blocking while also providing additional thermal insulation. It has a reinforced, foil-faced exterior to optimize heat mitigation and transfer. With use of matching tape, duct lagging allows for convenient installation and noise reduction of up to 20 decibels.
Isolation hangers are also a useful and effective way to decouple vibrating HVAC equipment from surrounding structures. They typically consist of flexible materials within a metal frame. The flexible materials serve to dissipate and absorb vibrations, separating them from the rest of the environment.
It is possible to quiet noisy HVAC equipment in both the exterior and interior environment, whether a facility is a factory, a data center, a performance venue, or anything in between.
At Oeler Industries, Inc., our experienced, seasoned professionals are all dedicated to creating the right solution within established timeframes and budgets. If your HVAC system is producing loud, unwanted sound, your one and only call should be to Oeler Industries.
Reach out to us at 1-800-4-0-NOISE or contact us online by clicking here.