SLIDE 1
Proposed Sound Rule for Wind Energy Facilities
Public Service Board Workshop Payam Ashtiani, B.A.Sc.
Aercoustics Engineering Limited PayamA@aercoustics.com
Dec 2 2016
Proposed Sound Rule for Wind Energy Facilities Public Service Board - - PowerPoint PPT Presentation
Proposed Sound Rule for Wind Energy Facilities Public Service Board - - PowerPoint PPT Presentation
Proposed Sound Rule for Wind Energy Facilities Public Service Board Workshop Payam Ashtiani, B.A.Sc. Aercoustics Engineering Limited PayamA@aercoustics.com Dec 2 2016 Noise Emission vs Noise Immission Emission: Noise emitted by a source
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Noise Emission vs Noise Immission
Emission: Noise emitted by a source Immission: Noise received at a given location
Emission Immission
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PRE-CONSTRUCTION NOISE MODELLING
Permitting Stage
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Pre-Construction Noise Modelling
- Industry accepted modelling methodology agrees well with post construction
measurements.
- Modelling methods should be standardized and prescribed
- Institute of Acoustics Good Practice Guide – May 2013
- ISO 9613-2 widely accepted
- Modelling parameters important:
- Ground factor (<=0.5)
- Termperature / Humidity
- Sound Power input used (Uncertainty considerations)
- Considerations for concave ground (valleys)
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POST-CONSTRUCTION NOISE MONITORING
Commissioning stage or in response to noise complaints
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Post-Construction Noise Monitoring
Informed by the past decade of measuring noise from large wind turbines Circa 2005-2007 Unattended simple noise monitors – short term Circa 2007-2008 Attended measurements short to medium term Circa 2008-2010 Sophisticated unattended noise monitors – long term Circa 2011-present More robust, cell connected noise monitors – long term Circa 2014-present Algorithms for objective tonality assessment
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Post-Construction Noise Monitoring - instrumentation
- Class 1 sound level meter and microphone
- Secondary wind screen for added protection against
wind induced pseudonoise
- Anemometer located near microphone
- Wind speed
- Wind direction
- Temperature
- Humidity
- Pressure
- Rain
SLIDE 9
- Preferably at locations with the highest predicted noise impact from the facility
- Locations where one can reasonably expected downwind conditions to occur more
frequently than others.
- Locations that are free of significant sources of noise contamination such as busy
roadways, heavily shrubbed or forested areas, or close to other commercial operations
Post-Construction Noise Monitoring - location
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- 1-minute intervals
Post-Construction Noise Monitoring – data filtering
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Post-Construction Noise Monitoring – data filtering
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- 1-minute intervals
- Valid if conditions are conducive to good quality data:
- No precipitation
- Separate daytime from nighttime (different fauna)
- Ensure turbines operating at high noise output
- Wind direction is not upwind (i.e. only downwind and crosswind acceptable)
- Wind speed measured at ground level less than 5m/s to minimize ambient noise.
- Remove intervals with transient events such as car passbys, etc
- Obtain sufficient number of valid data points with Turbines ON and OFF
- Bin the data by wind speed and compare ON vs OFF
- Determine the Turbine contribution through logarithmic subtraction of ambient
Post-Construction Noise Monitoring – data filtering
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Post-Construction Noise Monitoring – data filtering
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Post-Construction Noise Monitoring – assessment
- Assessment made based on the mean or logarithmic average of the
levels by windspeed
- Facility contribution determined by ambient correction with data from
the same wind bin
- Assessment made when there is sufficient data acquired – at least 20
points within a wind bin
- NOTE: Any 1 individual minute above or below the limit does not
constitute an assessment of compliance or non-compliance.
- NOTE: the nature of ambient noise is changing constantly and it would
be difficult to defend certainty in knowing if one individual minute was not unduely influenced by transient event contamination
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Tonality
- Tonality determined by analyzing narrow-band frequency spectra
- Objective measure of the prominence of a tone
- Less prone to false negatives than the current 1/3rd Octave method
SLIDE 16
Thank you
Payam Ashtiani, B.A.Sc.
Aercoustics Engineering Limited PayamA@aercoustics.com
Dec 2 2016