Wind Turbine Sound Level Prediction
An on-line spreadsheet should be visible. This was written using Zoho Sheets, at http://www.zoho.com, and can be viewed by most browsers; please let us know if you have any difficulties with access.
When designing a wind farm, impact upon neighbours is one of the most important considerations. There are three issues to consider - the view of the turbines, shadow effects and noise impact. This spreadsheet is a much simplified version of the tool we use for assessing sites for noise impact, and has been limited to three turbines.
This interactive spreadsheet calculates the way sound levels diminish with distance, and also allows for the way air density helps reduce sound levels. The noise levels from individual machines are combined using a logarithmic formula, giving an overall total. The program does not take into account ground conditions, or any barrier effects from land, houses or vegetation.
You can change any of the variables in the green box, such as turbine noise level, height and distance to the windfarm. The end result is an indication of sound power level, which has to be less than 45dB(A) to avoid being intrusive. Note that some councils are suggesting that windfarm noise should be limited to 35dB(A), equivalent to rural background noise levels, however national guidelines do allow for sound levels up to the 45dB(A) limit for project owners.
This tool only provides an indication of sound levels and more detailed work is normally required for actual site assessment. We hope you find this useful, and please get in touch if you need more detailed information. Please note that this tool has been made available under a creative commons licence.