Wind Farm Noise Impact Assessment PLANNING POLICY & ETSU-R-97

Renewable Development & Noise NSNA EPA COPA Energy Act Climate Change Act BS 4142 BS 8233 ETSU-R-97 Planning system to deliver renewables … Scotland WHO EU Directives Kyoto Protocol www Onshore WTs SPP PAN1/2011

The EU and UK wind resource The UK has the best wind resource in Europe

Wind Farm Noise - the basic aims …. Demonstrate acceptable wind farm noise impact at the planning stage Achieve this acceptable noise impact in practice Balance local noise impact against wider benefits (generating capacity)

Scottish Planning Policy – PAN1/2011 Good acoustical design and siting of turbines is essential to minimise the potential to generate noise. Web based planning advice on renewable technologies for onshore wind turbines provides advice on The Assessment and Rating of Noise from Wind Farms (ETSU-R-97) published by the former Department of Trade and Industry [DTI] ….

Onshore Wind Turbines (as updated 17 July 2013) - Noise PAN on Planning and Noise provides advice on the role of the planning system in helping to prevent and limit the adverse effects of noise. The associated Technical Advice Note provides guidance which may assist in the technical evaluation of noise assessment.

Onshore Wind Turbines (as updated 17 July 2013) - Noise The report, "The Assessment and Rating of Noise from Wind Farms (ETSU-R-97) ….. should be followed by applicants and consultees, and used by planning authorities to assess and rate noise from wind energy developments, until such time as an update is available. This gives indicative noise levels thought to offer a reasonable degree of protection to wind farm neighbours, without placing unreasonable burdens on wind farm developers ….

Onshore Wind Turbines (as updated 17 July 2013) - Noise A further report produced by Hayes McKenzie for DECC … An Analysis of How Noise Impacts are Considered in the Determination of Wind Farm Planning Applications suggested that best practice guidance is required to confirm and, where necessary, clarify and add to the way ETSU-R-97 should be implemented in practice ….

Onshore Wind Turbines (as updated 17 July 2013) - Noise The Institute of Acoustics (IOA) has since published Good Practice Guide to the Application of ETSU-R-97 for the Assessment and Rating of Wind Turbine Noise. The document provides significant support on technical issues to all users of the ETSU-R-97 method for rating and assessing wind turbine noise, and should be used by all IOA members and those undertaking assessments to ETSU-R-97. The Scottish Government accepts that the guide represents current industry good practice.

Onshore Wind Turbines (as updated 17 July 2013) - Noise Further research by AECOM entitled NANR Wind Farm Noise: Statutory Nuisance Complaints Methodology is aimed at helping Local Authorities deal with wind farm noise complaints, using statutory nuisance powers

Noise Policy Statement for England What does minimise increases in noise mean in the context of noise policies? … taken in isolation and to a literal extreme, noise minimisation would mean no noise at all. In reality, although it has not always been stated, the aim has tended to be to minimise noise as far as is reasonably practical the application of the NPSE should enable noise to be considered alongside other relevant issues and not to be considered in isolation. In the past, the wider benefits of a particular policy, development or other activity may not have been given adequate weight when assessing the noise implications.

Baseline 45 MW Consider effect of 2 dB(A) reduction Effect of 2dB(A) at one property 36 MW Effect of 2dB(A) at all properties 27 MW A 2dB(A) difference in noise level is generally considered to be subjectively insignificant – what is the correct planning balance?

The situation to be addressed …. Source Propagation Receiver

Wind Farm Noise – setting acceptable limits ETSU-R-97

BS4142 was used as a helpful starting point but recognised as having a number of practical limitations … Wind farms are likely to be developed in largely rural areas and not in the areas to which the BS4142 standard is principally addressed, namely mixed residential and industrial areas The scope of BS 4142 specifically precludes situations where background noise levels lie below 30 dB(A) but such low levels can be encountered in rural areas BS 4142 recommends that noise measurements should not be taken in extreme weather conditions such as high wind speeds greater than 5 metres per second average – just those conditions under which wind farms would be operating

… but it appears to have been accepted that the general principles of BS4142 should be retained … like should be compared with like specific noise assessed against background noise under the same conditions special consideration given to situations of low noise levels time of day effects for background mode and time of operation effects for specific noise wind effects (direction and speed) use of robust metrics L A90 versus L Aeq (specific to wind farm noise)

Use of the L Aeq,T index for the measurement of specific noise levels in quiet rural areas is highly susceptible to corruption by natural sources of noise

VHVH Both turbine noise and background noise are wind speed dependent VLVL

Steps for undertaking an ETSU-R-97 assessment Specify the location of wind turbines and a candidate type of turbine Identify the locations of the nearest noise sensitive properties (or groups of properties) Determine whether noise immission levels exceed 35dB(A) Measure background noise levels as a function of site wind speed at nearest neighbours, or at least a representative sample of such Determine the day-time and night-time noise limit curves from the measured background noise levels Calculate the noise immission levels at the neighbouring properties Compare calculated wind farm noise levels with derived noise limit curves to ensure ETSU noise limits will not be breached

Measure the existing (inherently variable) background noise level at selected locations as a function of site wind speed and time of day Assessment property – quiet daytime or night time

Calculate the average background level by fitting a best fit curve to the measured noise data Assessment property – quiet daytime or night time

Set the ETSU-R-97 noise limit at 5dB(A) above the background noise curve but with an absolute lower limit day night involved Assessment property – quiet daytime or night time

Calculate wind farm noise immission levels at receptors and compare with ETSU noise limits Noise Propagation Calculation Algorithm Wind Farm Noise Immission Level ETSU-R-97 Noise Limit

The Institute of Acoustics Good Practice Guide Response to request to IoA from DECC Follow up to HMP report Applies to all turbines above 50kW Formally endorsed in Scotland -consultation & engagement -background noise surveys -wind and rain measurements -data analysis and noise limit derivation -noise predictions -cumulative noise issues

Summary of current situation The majority of wind farms designed using ETSU-R-97 appear to be operating successfully without noise issues? Site-specific noise issues have occurred that need to be better understood/managed Operational noise management is possible with current technology wind turbines to mitigate noise effects Amenity of neighbours and a proactive attitude towards noise concerns remains of paramount importance but Inaudibility at all locations and at all times is not a realistic proposition Fears of adverse noise effects may be causing undue stress even before wind farms are constructed

Summary of current situation Either Noise will prevent renewables targets from being met or Noise will result in many more wind farms being built There is an urgent need for a consensus view within the industry, along with improved public engagement, as to those acoustic factors which are truly relevant.

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