Standards New Zealand has released for public comment a draft Standard DZ 6808 Acoustics – Wind farm noise. The purpose of this Standard is to provide suitable methods for the prediction, measurement and assessment of sound from wind turbines for use in both wind farm development and local authority planning procedures. This Standard also provides guidance on the limits of acceptability for sound received at noise sensitive locations emitted from wind farms containing one or more wind turbines.
DZ 6808 is a revision of NZS 6808:1998 Acoustics – The assessment and measurement of sound from wind turbine generators. The 1998 version was written prior to significant wind farm development in New Zealand. The basic methodology proved robust, but experience and research over the following decade brought to light numerous refinements and enhancements which are now addressed in the revised draft.
The terminology and format of the Standard have been updated to align with the 2008 editions of NZS 6801:2008 Acoustics – Measurement of environmental sound, and NZS 6802:2008 Acoustics – Environmental noise. This includes adopting L90 in place of L95 as a measure of sound levels.
The original recommended noise limits are retained, but are added to by provision for a more stringent secondary noise limit where justified by particular local circumstances. The simple prediction method in the 1998 version has been removed, and replaced by methods using octave-band calculations, which account for a wider range of factors influencing sound propagation. Measurement procedures have been clarified and wind speeds are now referenced to the wind turbine hub-height.
Standards New Zealand invites comments on the draft Standard up to 30 April 2009. The technical committee that prepared the draft Standard will then consider each public comment received and reach consensus on any changes that may be necessary. The revised Standard is expected to be published in October 2009.