HVAC equipment is one of the major sources of noise in a building, and its effect on the interior acoustical environment is important. Further, noise from outside equipment often propagates to the community. Therefore, mechanical equipment must be selected, and equipment spaces designed, with an emphasis on both the intended uses of the equipment and the goal of providing acceptable sound levels in the occupied spaces of the building in which the equipment is located and in the community. Furthermore, operation of HVAC equipment causes vibrations that can propagate into occupying spaces. Vibration can create uncomfortable conditions for occupants, and often creates secondary noise sources (eg, vibrating walls, floors, piping and ducts).