a practical guide to noise and vibration control for hvac systems second edition pdf
Since the publication of the 1991 edition of this guide, building owners and
managers have been paying more attention to occupant comfort, and municipal
codes have become more attentive to property-to-property noise emissions. As a
result, the HVAC community has become much more sensitive to the acoustical
design of its products and systems.
Many equipment manufacturers are producing
quieter products and sometimes use the acoustical benefit as the primary marketing
feature. Increased attention to product acoustical performance is evidenced by the
fact that the number of HVAC acoustical testing laboratories has almost doubled
since 1991. Also, increased internationalization has permitted access to low-noise
HVAC products from Europe and Asia.
System designers are paying closer attention to the acoustical performance of
the products and systems that they specify, and many building owners now require
acoustical consultants on project design teams.
Unfortunately, not all industry changes have been for the quieter. Energy-efficient
screw (rotary) compressors have been the source of many noise and vibration
complaints, and the momentum to remove internal acoustical liner from ductwork, or
to cover it with solid sheet metal in air-handling units and terminal boxes, has reduced
the palette of noise reduction strategies that can be used in system designs. These and
other factors increase the importance of system design in the form of more careful
attention to vibration isolation and the airflow aerodynamics in air distribution
Therefore, the main theme of this guide has not changed over the past 20
years—that is, most HVAC system noise and vibration problems are system problems
that are due to the improper selection, design, or installation of the components into
a complete system. More careful attention to these factors will greatly reduce the
number and severity of noise and vibration complaints.