ANSI S12.60 (2002) testing of modular buildings used as classrooms

Abstract

The acoustics of modular buildings used as classrooms may come under greater scrutiny if schools adopt American National Standards Institute (ANSI) S12.60 (2002) ‘‘Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools’’ as required thresholds of performance. To quantify the benefits of series of structural improvements to buildings having an interior volume of less than 10<th>000 ft3, both the reverberation time and background noise were measured. Interior spaces were unoccupied as per S12.60, but unfurnished. Reverberation times were 0.4–0.6 s. The background noise level was measured to identify the contributions of exterior sources, interior fluorescent lighting, and AC/Fan systems operating with/without a plenum for the return vent. Targets for the stated room volume are 35 dBA and 55 dBC. For the final configuration, interior noise levels with lights, fan, and cooling active were 43 dBA and 67 dBC; interior noise levels due to exterior sources were 33 dBA and 58 dBC due in part to the surrounding industrial land uses and nearby freeway. For one configuration, with the fan active without AC, pressurized air escaping through a 1/4-in. gap beneath the 36-in.-wide door produced a distinct 35 dBA tone in the 630-Hz third-octave band.