A proposed method for measuring noise from wind farms for the purpose of determining compliance with applicable limits and the comparison of results to ISO 9613-2 predictions

Abstract

This paper describes methods for the measurement of noise emissions from utility-scale wind farms and the analysis of the resulting data for determining compliance with noise level limits and standards. The methods call for primarily unattended monitoring of noise levels, wind speeds, and turbine operating conditions over many weeks, in some cases months, in order to capture the recurring maximum turbine-only noise level at a receptor (e.g., residence). This condition occurs when the nearest turbines are producing full acoustic output, while noise from background sources is very low (particularly that from wind). This paper will present the results of noise compliance measurement studies applying these methods conducted by Hankard Environmental, encompassing over 13 projects and over 50 measurement locations in the Northeast, Midwest, and Plains regions of the United States (U.S.) The results of these measurements are used to assess the accuracy of the ISO 9613-2:1996 method in predicting wind turbine noise levels on both an overall A-weighted and octave band basis. These results can be used by wind energy developers to accurately design projects to meet applicable limits and standards and gives all parties in the permitting process a greater degree of confidence in predictions and compliance measurement results.