Wind Farm Noise Assessment by XL2

One of the largest acoustic consulting firms in Australia, “Renzo Tonin & Associates” was engaged by the New South Wales Department of Planning & Industry to conduct wind farm noise assessments. The goal was to perform a specialist, independent acoustic compliance audit of three major wind farms located near Canberra, Australia’s capital city.

The objective of the study was to conduct a detailed noise assessment at residential dwellings near to the wind farms. Three wind farms near Canberra, Australia, were investigated. These are the Cullerin Range Wind Farm (operating 15 RePower MM82 and MM92 wind turbines), the Woodlawn Wind Farm (using 23 Suzlon S88 wind turbines) and the Capital Wind Farm (running 67 Suzlon S88 wind turbines).

XL2 Sound Level Meters used for Noise Monitoring
XL2 Sound Level Meters were operated on a continuous basis, typically over a six week period at each wind farm. Altogether 6 XL2’s were used for unattended noise monitoring at each of these locations. Attended noise monitoring was also used to determine whether penalties apply in the calculation of annoyance levels for tonal, low frequency, impulsive or intermittent noise. The principal project manager, Dr. Renzo Tonin, reported: “The XL2 is a class 1 instrument having an accuracy suitable for field and laboratory use. It incorporates 1/1 and 1/3 Octave band filters as well as continuous audio recording. The lower limiting frequency of the XL2 is just 5 Hz and it exhibits a very low residual noise floor which makes it eminently suitable for use at wind farm sites which are typically located in quiet rural locations.”

Dedicated Setup for Wind Farm Monitoring

The XL2 meters were housed in Pelican cases with the XL2 preamplifier extension cable threaded through an aluminum tube with a weatherproofing gland at the top to protect and seal the preamplifier connection. The XL2 was battery powered to enable continuous noise logging for two weeks at a time at each residential site. Special windscreens, 200 mm in diameter, were used to reduce the impact of wind noise on the microphone. The recorded data was then processed in accordance with the relevant standards specified in the conditions of consent for wind farms. For example the following chart illustrates the LA90 level, which is the statistical noise level exceeded during 90% of the measurement period, depending on the wind speed shown on the X-axis.

Chart with 3’773 individual LA90 data points in reference to the wind speed

This method of analysis is typical of many wind farm standards, one of which is ETSU-R-97 commonly used in the UK. The full noise assessment reports are available for download.

Projects successfully completed
Dr. Renzo Tonin summarized: “We selected NTi’s XL2 sound level meters for the noise monitoring program because of their environmental robustness, ease of use and value for money. The project was successfully completed in the allotted time and on budget.”

Renzo Tonin & Associates is one of the largest acoustic consulting firms in Australia with offices in Sydney, Melbourne, Brisbane and Kuwait. The company employs specialists in environmental noise, building acoustics, structural dynamics and expert witness work.

NTI is distributed in Australia by Amber Technology.