Italian guidelines about wind turbine sound: PO. ID How to improve them and make them work better C001 Martina Repossi Alerion Clean Power S.p.A. – Milan (Italy)

Abstract Critical topics about Italian landscape

Wind turbines can produce unwanted sound (referred to as noise) during operation. The nature of sound As a matter of facts, Italian population density, at 197 inhabitants per square kilometre (ISTAT Report, 2013), depends on wind turbine design. Propagation of the sound is primarily a function of distance, but it can also be is higher than that of most Western European countries. However, the distribution of the population is widely affected by turbine placement, surrounding terrain, and atmospheric conditions. uneven. The most densely populated areas are the Po Valley (that accounts for almost a half of the national In Italy, unlike other European countries, we don’t have specific legislation about windmills sound population) and the metropolitan areas of Rome and Naples, while vast regions such as the Alps and measurement and noise limits from Law no.447 are not functional for noise verifical for wind farms. Public Apenins highlands, the island of Sardinia and the plateaus of Basilicata are very sparsely populated. health is an essential Constitutional right (art.32 from Italian Constitution: "la Repubblica tutela la salute come Besides that, Italian landscape is full of protected areas in order to guarantee environmental conservation. The fondamentale diritto dell'individuo e interesse della collettività”) and disagreements related to wind farms noise consequence is that designers need to adapt wind farms layouts to these constraints, also because most are actually recurring. In January 2012, “Massachusetts Department of Environmental Protection. Turbine windy sites have already been occupied by wind farms. That’s why big and noisy wind turbines have been Health Impact Study: Report of Independent Expert Panel” reported that there is insufficient epidemiologic lately installed in the countryside or mountainside but nearer and nearer industrial and of course inhabited evidence to determine whether there is an association between noise from wind turbines and annoyance areas. Currently, we have “old” wind farms (installed about 15-20 years ago) which electro-mechanic independent from the effects of seeing a wind turbine and vice versa. Anyway, although investigators may not components are fatigued, and new big ones which technology is certainly improved, but can produce noise know the exact nature of the relationship between noise and health impacts, environmental noise pollution can because of their growing size. have serious implications for public health. Energy companies are properly requested to monitor the effects of windmills noise and preserve people from having consequences due to this aspects. To reach this significant goal, some authorities (i.e. ISPRA “Istituto Superiore per la Protezione e la Ricerca Ambientale”) are elaborating studies in order to define methods for measuring windmills noise. When more information and studies become available, best practices can be developed and adopted. Moreover, wind turbine noise control systems are improving, so we can reduce their noise impacts on the surroundings. That’s why we would need to create a standardized system both for developers and inhabitants in order to make them live together and solve reciprocal problems without controversy. Italian law on wind farms noise

In Italy the most important national law that deals with acoustic impact was approved about 20 years ago (Law no. 447/1995); Hydrologycal constraint this law gave “general guidelines on acoustic pollution” and tried Water courses buffer zone Forests buffer zone to find the fundamental principles about protecting indoor and outdoor spaces from noise. It also established that the Region Table 4 – Ranking and Thematic map of the “Demographic density” in Italian Regions Picture 5 – PCN (Portale Cartografico Nazionale) map with Picture 6 – Hydrologycal constraints and buffer zones around evidence of IBA, ZPS and SIC areas a wind farm Office must define rules about acoustic impacts, like town zoning In part because of the expected wind development in more-populous areas, empirical investigations into and the definition of acoustic redevelopment plans; moreover, related community concerns are required; indeed, many times neighbours complain about discomfort due to some competencies are up to Provincial Districts and even wind farms (e.g. sleeplessness, nausea, headaches), even if their relative distance from wind turbines was Municipalities, causing more and more decentralization in the judged not dangerous for noise impact during development phase. Moreover, another critical point is related to regulatory system. This rule set the basis for specific decrees that Class I – Protected areas low frequency sound; here we are some relevant researchers' statements about this aspect: came later: in fact, the guidelines given by LQ 447/95 aimed to Class II – Residential areas Class III – Mixed use areas Infrasound from Wind Turbines – Facts, Fiction or Deception - Dr. Geoff Leventhall regulate organically the subject of noise, then a series decrees Class IV – Intense human activities areas Class V – Mainly industrial areas – "Frequencies below 40 Hz cannot be distinguished from the background noise due to wind; put in act those principles. The first important law was the Prime Class VI – Industrial areas – There is insignificant infrasound from wind turbines and there is normally little low frequency noise; Minister Decree 14/11/97 about the determination of the legal Picture 1 – Graphical acoustic classifications according to DPCM 14/11/97 – Attention should be focused on the audio frequency fluctuating swish, which some people may well find to be very disturbing and limits of acoustic sources. Moreover the DPCM 14/11/97 stressful, depending on its level.” confirmed the outline introduced by the previous DPCM 1/3/91, Do wind turbines produce significant low frequency sound levels? - G. P. van den Berg “It is clear from the spectra that most energy is found at lower frequencies. This does not imply it is relevant for hearing as human hearing however is relatively insensitive by setting the absolute input limits in a unique table for all kind of at low frequencies. Indeed, the correlations show that the most audible energy near the turbines is contained in the 1/3 octave acoustic sources (Tables 1 and 2). In houses with open windows band levels with frequencies from 400 through 3150 Hz. […] It is clear that the sound below appr. 20 Hz must be considered absolute noise can’t exceed background noise more than 3dB inaudible for even well hearing people, even when one stands close to the turbine.” during the night and 5dB during the day. This criterion doesn’t apply to industrial areas and nearby roads. At last, different noise Table 1 – Acoustic classifications and emission noise limits within municipality lines Recommended noise mitigation strategy limits are prescribed for municipalities that didn’t provide acoustic classification. Anyway, although investigators may not know the exact nature of the relationship between noise and health Consecutively, lots of different regional guide lines contributed to impacts, or why noise affects some people differently than others, the evidence suggests that environmental create more confusion about legislative environment; for noise pollution can have serious implications for public health. Some new technical instruments are to be instance, in Sardinia, regional guide lines named “Regional tested in order to control wind turbine sound (active interventions): lately, researchers have been focused on Directives about environmental acoustic pollution" (DGR n. 62/9 reducing noise without affecting the power generated by the wind turbine. The point is to limit the noise del 14/11/2008) define how to draw attention to some areas Table 2 – Acoustic classifications and immission noise limits within municipality lines produced by each functioning turbine and thereby comply with local regulations regarding noise emission. according to their use: every area corresponds to different This allows Italian wind farms to be located close to urban areas, limiting the environmental impact they imply. acoustic limits that must be respected by new infrastructures or Some noise reduction systems, to be installed as additional modules on top of the basic SCADA, for instance, manufacturing activities. Moreover, in Tuscany, "Regional guide can be programmed in order to control wind turbines production (ref. Table 5 below); they also consider wind lines for the environmental impact assessment of wind farms“ directions and modify settings from day to night, according to law limits. At last, wind turbines could be (2012) define a "1km area" around the wind farm site, called stopped at low wind speeds because of their prevalent sound on residual noise; in fact, the rotational speed "panoramic area", to be analysed with an accurate measuring decrease reduces power output, and therefore systems should only be implemented within a certain range of campaign at every single receptor. Table 3 – Acoustic classifications and emission noise limits without township lines wind velocities, since high winds also have the added benefit of masking the sound of the wind turbine with the sound of the wind itself. Moreover, planting vegetable filters can reduce noise, as much as installing anti- noise windows: anyway, these kind of passive interventions can paradoxically increase differential limits, Technical rules and evaluation methods unless they are able to decrease noise to an imperceptible value. In the end, proactive noise monitoring promotes effective cooperation with neighbours that can prevent conflicts before they arise, and quickly Despite this complicated but accurate legislative body, that allows to define "sound acceptability", in case of resolve those that do by clearly proving ongoing compliance; that's why more and more Environmental Italian controversy the Court Technical Consultant usually refers to what we call "sound tolerability", a sort of Authorities are suggesting these interventions to energy developers and producers. subjective reaction depending on people personal perception, referring to Constitutional health right (article no. 32); that's why noisy activities, like wind farms, that respect "acceptability" limits, can be stopped because of "tolerability" ("tolerability" based on the civilistic approach, uses to the so-called "comparative parameter", a more restrictive, but less accurate criterion than noise level limits defined by law). Moreover, art. 844 of Italian Civil Code specifies that the Judiciary Authority must mediate between production needs and owner’s rights, counterposing inviolable public health right to renewable energy production (which plants are defined of public usefulness, not deferable and urgent ones by 387/03 Legislative Decree). In addition to that, from a technical point of view, fixed rules both for wind turbines noise level (IEC 61400-11) and for methods for the evaluation of acoustic impacts have been recently released. Unfortunately, IEC 61400- 11 gives all the right issues to measure wind farm noise at ground level but just for one single turbine. If we want to know noise levels at receivers, we have to extend measured data through an acoustic model which can predict how noise spreads. Besides this, in 2013 the Unification Italian National Office (UNI) released a technical rule (UNI 11143) about «Method for the evaluation of the acoustic impact and climate according to different sources - Part 7: Wind turbine noise», that describes different methods for estimating the acoustic Picture 7 – Variation in power according to noise level and wind (Noise reduction system) Table 5– Different turbine noise levels using Noise Reduction Systems impact of wind turbines through an experimental characterization of the acoustic climate of a wind site. It suggests to evaluate a 500m area around the wind farm, with in-depth fact-finding surveys, as for receivers, land use, wind farm layout, anemometers, local regulation; it also considers wind direction and intensity, both References affecting wind measurements. The same is for recent ISPRA guidelines; anyway, even if these technical rules 1. DPCM 1.3.91 on protecting room environment and outdoor environment from noise pollution; are valuable in terms of standardised systems, they’d need to be officially adopted by Italian regulation in 2. Law n.447/95 containing prescriptions about general noise impact assessments; order to represent a unique path for professionals and developers. 3. DPCM 14.11.97, determining limit values of noise sources; 4. DM 16.3.1998, detecting and measuring techniques for noise pollution; 5. “Regional Directives about environmental acoustic pollution" (DGR n. 62/9 del 14/11/2008); 6. “Regional guide lines for the environmental impact assessment of wind farms” (Tuscany Region, 2012); 7. Guidelines for evaluating and monitoring wind farms acousting impacts - ISPRA “Istituto Superiore per la Protezione e la Ricerca Ambientale” – Nov. 2013; 4. Italian Civil Code, art. 844 “Immission ban”; 5. International Standard IEC 61400-11 Wind turbine generation systems – Part 11: Acoustic noise measurement techniques; 6. UNI 11143-11: «Method for the evaluation of the acoustic impact and climate according to different sources - Part 7: Wind turbine noise»; 7. Effects of industrial wind turbine noise on sleep and health, "Noise & heath", Volume 14, Issue 60, 2012 - Michael A. Nissenbaum, Jeffrey J. Aramini, Christopher D. Hanning; 8. Wind Turbine Syndrome. A report on a natural experiment (2009) Journal Article, Name of Journal - Nina Pierpont; 9. C. Hanning, Wind Turbine noise, sleep and health. Response to "The Northumberland County Council Core Issues and Options Report Consultations", 2012; 10. http://www.nextville.it “NextVille” website, renewable energies and energy efficiency;

Picture 2 – Noise measurement setup according to IEC 61400-11 Picture 3 – Noise measurement algorithm Picture 4 – Area on a turbine 11. Italian demographic density: ISTAT, Statistics National Institute – 2013 Report according to UNI 11143 blade with largest sound production

Wind turbine sound 2014 – Technology Workshop, Malmö, 9-10 December 2014