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Slide 2 www.hoarelea.com Wind Farm Noise Impact Assessment INTRODUCTION AND OVERVIEW OF THE DAY Slide 3 www.hoarelea.com Hoare Lea founded in 1862 Extensive experience in wind farm noise assessments since the early 1990s 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 Slide 4 www.hoarelea.com The options . Offshore large scale (>100kW) Onshore large scale (>100kW) Onshore medium / small / micro scale Building mounted / integrated medium / small / micro scale Slide 5 www.hoarelea.com 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 Slide 6 www.hoarelea.com 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 Slide 7 www.hoarelea.com 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) Slide 8 www.hoarelea.com 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 Slide 9 www.hoarelea.com Where is wind farm noise on the scale? So wheres the problem? Slide 10 www.hoarelea.com 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 Slide 11 www.hoarelea.com 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 Slide 12 www.hoarelea.com 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 Slide 13 www.hoarelea.com 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 Slide 14 www.hoarelea.com 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