Acoustics: Wind farm noise — New Zealand Standards public comment draft 

Version 2.5, 2 Feb. 2009

Closing date for comment: 30 April 2009

Comment on line or download comment form: http://www.standards.co.nz/web-shop/?action=viewDraft&draftId=DZ6808&mod=drafts

This Standard covers the prediction, measurement and assessment of the received sound from wind farms. It recommends noise limits that balance the need to avoid disturbance to people living in the vicinity with the need to provide for development of a source of renewable energy.

Limits for wind farm noise are required to provide protection against sleep disturbance and maintain reasonable residential amenity.

In order to provide a satisfactory level of protection against sleep disturbance, this Standard recommends an upper limit of wind turbine sound levels outdoors at residential locations of 40 dB L90.

Primary noise limit

As a guide to the limits of acceptability, at any wind speed wind farm sound levels (LA90(10 min)) should not exceed the background sound level by more than 5 dB, or a level of 40 dB LA90(10 min), whichever is the greater. The noise limit applies at every point within the notional boundary of any noise sensitive location.

Secondary noise limit

In most circumstances the primary noise limit will be adequate to protect health and some degree of amenity. However, at some locations a secondary noise limit may be desirable to afford a greater degree of protection during evening and night-time. A secondary noise limit should only be considered where:

a) Background sound levels during evening or night-time are commonly less than 25 dB when the wind farm sound levels are predicted to exceed the background sound level by 10 dB or more; or
b) Objectives or policies in a district plan promote a higher degree of protection of amenity, related to the sound environment of a particular locality, than generally applies in a district; or
c) District plan rules require a higher degree of protection of amenity related to the sound environment of a particular locality.

Where a secondary noise limit is applicable, wind farm sound levels (LA90(10 min)) should not exceed the background sound level by more than 5 dB, or a level of 35 dB LA90(10 min), whichever is the greater. The noise limit applies at every point within the notional boundary of an existing noise sensitive location where a secondary noise limit is shown to be justified. The secondary limit only applies when the wind speed at the hub-height of the nearest wind turbine is less than 6 m/s, during evening and night-time. During daytime and for higher wind speeds the primary noise limit should always apply. It is recommended that wind farm noise limits should not be set lower than 35 dB L90 at any time.

Claims have been made that low frequency noise and vibration from wind turbines have caused illness and other adverse physiological effects among a very few people worldwide living near wind farms. The paucity of evidence does not justify, at this stage, any attempt to set a precautionary limit more stringent than those
recommended [above].

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