Standardizing wind turbine sound predictions

Permitting a new wind energy project often requires modeling of expected operational sound levels. In the United States, acoustical modeling of wind energy projects has historically relied on sound power levels based on IEC 61400-11 and the ISO 9613-2 propagation methodology. While current practice in the United States yields relatively minor differences, standardization of predictions is anticipated to result in a robust and repeatable process that increases regulatory confidence. American Clean Power (ACP) is recognized by the American National Standards Institute (ANSI) as an Accredited Standards Developer. ACP established a working group which reached consensus on a preferred method of predicting project sound levels during the siting and permitting process. The goal of this standard is to establish uniform method of predicting future projects sound levels such that pre-development sound assessment results can be readily compared. A standardized calculation method ensures calculated results are repeatable, uniform, and more easily understood by all interested parties.