Wind turbine noise assessment

We conduct wind farm noise assessment using WindPRO 2.7 software. WindPro is the worlds most used software package for the design and planning of wind energy projects.

In Estonian legal system the concept of noise is described by the Ambient Air Protection Act which defines noise as unwanted or harmful outdoor sound created by human activities created by stationary or mobile sources of pollution.

There are no specific standards in Estonia for the noise created by wind generators, but the analogue for stationary and continuous noise has been an industrial enterprise working around-the-clock and which fulfils the standards applying to industrial noise have been followed.

Usually 40 dB(A) (target level for newly planned areas during night time in residential areas) is taken as a noise limit for new wind farms.

The sources of noise emitted from wind turbines are divided into mechanical and aerodynamic. Aerodynamic noise is produced by the flow of air over the blades.

All turbine manufactures declare noise levels for their turbines. Those values are  usually sound emission levels that are measured from the centre of the rotor when wind speed is 8 m/s at 10 m above ground for a turbine sited in an open landscape with roughness class of 1.5. If the sound emission level is known, the sound emission level for certain distance can be calculated.