Basic Documentation

Chapter 6–Minimizing HVAC Sound
Chapter 6 offers general guidance as a convenient summation on minimizing excessive or
objectionable HVAC sound. It includes the following topics:
• Introduction to minimizing HVAC sound
• Basic system design criteria
• Fans
• Duct configurations
• Terminal equipment
• Sound attenuation devices
• Sound measurement instrumentation
Introduction to Minimizing HVAC Sound
In the previous sections, procedures were established for calculating the sound power levels
generated, and the attenuation effect for nearly all of the elements that comprise an HVAC
system. Based upon the formulas, tables, charts, and graphs in the preceding sections, the
following guidelines are offered as a convenient summary on minimizing excessive or
objectionable HVAC sound.
Following these guidelines will help attain an HVAC system design with the lowest practical
ambient sound level. But remember, the objective is not a “nearly silent” system, but one that
will provide a desirable background sound level that is conducive to the type of occupancy or
activity to be performed in the conditioned space.
See Table 29 for suggestions regarding reducing annoying sound in existing ventilation
systems.
Basic System Design Criteria
• Mechanical rooms should never be directly above or below noise sensitive rooms.
• Mechanical equipment (fans, pumps, etc.) should be installed utilizing vibration
absorbing concrete pads, adequate vibration isolating equipment, and ample spacing
from walls ceilings, and structural members.
• In general, HVAC systems utilizing efficient air delivery designs will generate and
transmit less sound than system configurations with higher pressure drops, higher
airflow velocities, and lower operating efficiencies.
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