Here is a paper from the Energy Collective, which includes a summary of noise regulations and setbacks. The writer’s conclusion is that worldwide regulation is needed, otherwise local regulation of noise is developed, with heavy influence from the wind power industry.
3-MW turbine south of Ottawa at Brinston: Ontario. Worldwide regulation needed to prevent wind industry influence [Photo by Ray Pilon, Ottawa]
December 19, 2016
Europe and the US have been building onshore wind turbine plants in rural areas for more than 25 years. Anyone living within about 1.0 mile of such plants would hear the noises year-round, year after year. Those nearby people would be experiencing:
- Decreasing property values.
- Damage to their health, due to lack of sleep and peace of mind.
- Living with closed windows and doors, due to year-round noises.
- Exposure to infrasound.
The wind turbine noise problem is worldwide. Due to a lack of worldwide guidelines, various political entities have been developing their own codes for the past 30 years. The World Health Organization is finally addressing the lack of detailed guidelines regarding such noises.
World Health Organization Noise Guidelines: WHO, publishes detailed guidelines regarding various, everyday noises, such as near highways and airports, within urban communities and in work places. The guidelines serve as input to local noise codes.
In general, wind turbines are located in rural areas. When they had low rated outputs, say about 500 kW in the 1960s and 1970s, they made little audible noise, and the infrasound was weak. However, when rated outputs increased to 1000 kW or greater, the audible and infrasound noises became excessive and complaints were made by nearby people all over the world.
WHO, which has not published any detailed guidelines regarding wind turbine noises, will be releasing environmental noise guidelines for the European region in the near future.
Worldwide guidelines regarding wind turbine noises are needed to protect nearby rural people, such as regarding:
- The maximum outdoor dBA value, how that value is arrived at, such as by averaging over one hour, where that value is measured, such as near a residence, or at the resident property line to enable that resident to continue to enjoy his entire property.
- How to measure, or calculate the outdoor-to-indoor sound attenuation of a residence.
- How much setback is needed, such as one mile to minimize infrasound impacts on nearby residents.
- The maximum dB value of infrasound, how that value is arrived at, where that value is measured.
- How to determine the need for a 5 dB annoyance penalty.
The lack of such guidelines has resulted in various political jurisdictions creating their own codes. That process has been heavily influenced by well-financed, pro-wind interests, which aim to have the least possible regulation to maximize profits.
Comparison of Wind Turbine Codes: Below are some highlights from the noise codes of various political entities to illustrate their diversity:
1) DENMARK: Because Denmark was an early developer of wind turbine plants, its noise code is more detailed than of most political entities. It has a buffer zone of 4 times total height of a wind turbine, about 4 x 500 = 2,000 ft, about 0.61 km (no exceptions), and it also has the following requirements regarding outdoor and indoor noise:
- For dwellings, summer cottages, etc.: 39 dBA (wind speeds of 8 m/s, 18 mph) and 37 dBA (wind speeds of 6 m/s, 13 mph)
- For dwellings in open country: 44 dBA (wind speeds of 8 m/s) and 42 dBA (wind speeds of 6 m/s)
The below regulations describe the methods and time periods over which sounds are to be measured:
- Page 4, par 5.1.1 mentions averaging over various periods. Only the worst average readings of a period are to be considered for compliance.
- Page 4, par 5.1.2 mentions a 5 dB annoyance penalty must be added to the worst average readings for a period for clearly audible tonal and impulse sounds with frequencies greater than 160 Hz, which would apply to wind turbine sounds.
- Page 6, par 5.4 mentions limits for indoor A-weighted low frequency noise 10 – 160 Hz, and G-weighted infrasound 5 – 20 Hz.
“If the perceived noise contains either clearly audible tones, or clearly audible impulses, a 5 dB annoyance penalty shall be added to the measured equivalent sound pressure level” That means, if a measured outdoor reading is 40 dBA (open country, wind speed 6 m/s), and annoyance is present, the reading is increased to 45 dBA, which would not be in compliance with the above-required 42 dBA limit.
In some cases, a proposed wind turbine plant would not be approved, because of the 5 dB annoyance penalties. The noise of wind turbines varies up and down. The annoyance conditions associated with wind turbines occur year-round. The annoyance conditions associated with other noise sources usually occur much less frequently.
NOTE: The 5 dB penalty does not apply to indoor and outdoor low frequency and infrasound noises, i.e., 160 Hz or less.
– For both categories (dwellings, summer cottages, etc.; open country), the mandatory limit for low frequency noise is 20 dBA (Vermont’s limit is 30 dBA), which applies to the calculated indoor noise level in the 1/3-octave bands 10 – 160 Hz, at both 6 and 8 m/s wind speed. The purpose of the regulation is to ensure neither the usual noise, nor the low frequency noise, will annoy nearby people when the wind turbines are in operation.
Denmark’s Controversial Noise Attenuation Calculations: The controversy in Denmark is regarding the Danish EPA assuming high attenuation factors for calculating attenuation from 44 dBA (outdoor) to 20 dBA (indoor, windows closed) for frequencies above 63 Hz, which yield calculated indoor noise levels less than 20 dBA. The Danish EPA prefers assuming high factors, because they result in compliance, which is favorable for wind turbines.
However, acoustics engineers have made indoor field measurements (supposedly “too difficult to measure”, according to the Danish EPA), which indicate many houses near wind turbine plants have lower than assumed attenuation factors, which results in indoor noise levels greater than 20 dBA, i.e., non-compliance, which is not favorable for wind turbines.
However, the final arbiters should not be government personnel using assumptions, but the nearby people. Increasingly, those people are venting their frustrations at public hearings and in public demonstrations.
2) POLAND is considering a proposed a law with a 2.0 km (1.24 mile) buffer zone between a wind turbine and any building. That means at least 65% of Poland would be off limits to wind turbines. Future wind turbine plants likely would be offshore. …
Read the full article here.