Calculating and specifying acoustical performance of exterior façade assemblies

Abstract

The acoustical performance of the exterior facade determines the noise exposure of residents to transportation noise. Facade assemblies with high acoustical performance have a large impact on construction in terms of cost, dimension, and schedule. Uncertainties in the acoustical performance require safety factors and generally conservative design in order to ensure that the requirements are met, with corresponding increase in impact to the project. Historically, STC ratings have been used to describe the performance of exterior facade assemblies. A variety of alternative ratings and calculation methods have been proposed to improve the accuracy or precision of the description. Examples include OITC and the spectrum adaptation terms of Rw defined in ISO 717-1. The authors have previously analyzed the use of OITC versus STC for describing the sound isolation of exterior facade assemblies [J. LoVerde and W. Dong, “Comparison of sound transmission class and outdoor-indoor transmission class for specification of exterior facade assemblies,” J. Acoust. Soc. Am. 141, 3539 (2017)]. This analysis is extended to additional ratings and methods with the goal of minimizing the uncertainty of the analysis. Recommendations for calculation and specification methods of the acoustical performance of exterior facade assemblies are presented.