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2 Wind Farm Noise Impact Assessment INTRODUCTION AND OVERVIEW OF THE DAY

3 Hoare Lea founded in 1862 Extensive experience in wind farm noise assessments since the early 1990’s Specialists in feasibility studies, noise impact assessments for planning, expert witness services, compliance monitoring, complaint investigation, detailed mitigation strategies and peer reviews State-of-the-art research in the field of wind turbine noise Members of DTI NWG (ETSU-R-97) committee Members of IoA Good Practice Guide committee Members of IEC61400-11 committee About Hoare Lea Acoustics

4 The options …. Offshore large scale (>100kW) Onshore large scale (>100kW) Onshore medium / small / micro scale Building mounted / integrated medium / small / micro scale

5 The economies of scale Power in wind = 0.5  A v 3  = air density A = swept area of rotor =  r 2 v = wind speed Power increases with …. cube of wind speed square of rotor radius height (increasing wind speed) … therefore locate large diameter rotors on high towers in areas of high wind speed

6 Typical installed capacity 2MW to 3MW Typical hub height 60m to 100m Typical rotor diameter 60m to 90m Typical height to blade tip 90m to 140m Onshore large scale turbines

7 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)

8 Diversity of energy supply is a necessity Renewables must play a key role in this diversity The UK has the best wind resource in Europe Large scale onshore wind is the key contributor in the immediate term There is a commitment to attain government targets Context of the need to attain this balance

9 Where is wind farm noise on the scale? So where’s the problem?

10 Wind farm developments are often in quiet rural areas Wind farms are designed to produce an ‘acceptable’ level of noise (in planning terms) ‘Acceptable’ does not necessarily mean inaudible Wind farm noise is likely to be audible at some neighbouring residences for at least some of the time Audibility may be unacceptable to some individuals Attitude and audibility are key …

11 When does sound become noise ? Depends on individual Depends on activity of individual Depends on attitude of individual Depends on hearing acuity of individual Depends on level of noise Depends on character of noise Image courtesy Bruel & Kjaer

12 Heart disease Raised blood pressure Gastric disorders Noise – an all encompassing definition The World Health Organisation (WHO) provides the following definitions: Noise - any sound that is damaging to health Health - a complete state of mental, physical and social well-being and not merely the absence of disease or infirmity Hearing damage Sleep disturbance Activity interference Annoyance Stress

13 Potential adverse effects of noise … Physical damage to structures Direct physical damage to humans (e.g. irreversible hearing damage) Secondary adverse health effects (e.g. stress, increased blood pressure, etc.) Activity interference (e.g. speech, sleep, work, relaxation, etc.) Annoyance Very high noise level Lower noise level

14 Assessment of ‘true’ impact Overall level - dB(A)Overall level - dB(A) Additional noise characteristics - tones etc.Additional noise characteristics - tones etc. Time of exposure – day/evening/nightTime of exposure – day/evening/night Actual duration of exposure to noiseActual duration of exposure to noise Activity during exposure – work/home/sleepActivity during exposure – work/home/sleep Expectations of sound environmentExpectations of sound environment Variability of noise – level/characterVariability of noise – level/character Masking effects of other soundsMasking effects of other sounds Variability of masking soundsVariability of masking sounds Attitude towards the source of noise Hearing acuity and general healthHearing acuity and general health Non-acoustic influencesNon-acoustic influences WHO <30% of noise problems are due to noise level Impact must be based on the likely response of a ‘representative’ sample population

15 Wind farms and current noise ‘issues’ …. Infrasound Low frequency noise (LFN) Ground-borne vibration Direct adverse health effects (WTS) Vibro-acoustic disease (VAD) Indirect (secondary) adverse health effects Sleep disturbance Use of background noise measurements Cumulative effects Effects of wind shear Effects of increased turbine size Noise propagation effects External to internal noise transmission effects Amplitude modulation (AM) Conditions

16 Wind Farm noise video …. promoters

17 Wind Farm noise video …. objectors

18 Thank you

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