Tricks are used to allow wind farms too close to habitations
In an email replying to the European Platform against Windfarms (EPAW), world-leading specialist in low-frequency sound Professor Henrik Moller of Aalborg University denounces the improper acoustic measurements carried out by Danish authorities. As a result, he says, the new regulations for wind farm noise are not in line with industrial noise standards. According to EPAW, this effectively constitutes discrimination against wind farm neighbors, which now have less protection than other citizens – in Denmark, but also in those countries that may take their cues from the small kingdom.
Henrik Moller and his team of acousticians have been consulted by DEPA, the Danish Environmental Protection Agency. But their recommendations have been ignored: “We had many objections to the proposal, but none of these were accommodated in the final version” (1). Answering a question from EPAW, the Professor explains how the new regulations will not effectively enforce the 20 dB(A) limit of low-frequency noise levels regarding wind farms, but that this limit is indeed being applied to other industries (2). Notes Mark Duchamp, of EPAW: “In reality, this is a case of double standards.”
In his email to EPAW dated Feb. 5, 2012, Professor Moller wrote: “All these errors sum up to probably not far from 10 dB, which means that the limit is suddenly not 20 but rather 30 dB(A). But the rules are claimed to give the same protection as for industrial sources, which is simply not true.” His letter is reproduced below (2).
“At low frequencies,” continues the Professor, “the perceived intensity, the loudness, increases more steeply above threshold than at higher frequencies. This means that when the level is a few decibels above the 20 dB limit, the consequences are more severe, than if a limit for higher frequencies is exceeded by the same amount. Few people would probably accept 25 dB(A) in their home at night and hardly anyone would accept 30 dB(A).”
Adds Duchamp: “It would appear that the Danish authorities have been cooking the figures to accommodate the wind industry. Years ago, governments were protecting tobacco companies; today, they absolve wind farms of all sins and help them commit more.”
The North-American Platform against Windpower (NA-PAW) joins EPAW in denouncing these manipulations which threaten wind farm neighbors within and beyond Denmark’s frontiers. EPAW and NA-PAW in turn are joined by the Waubra Foundation, Australia’s best known organization investigating the serious health issues affecting wind farm neighbors.
Mark Duchamp +34 693 643 736 (Spain); Skype: mark.duchamp; Executive Director, EPAW
Sherri Lange +1 416 567 5115 (Canada); CEO, NA-PAW www.na-paw.org; email@example.com
Dr Sarah Laurie +61 439 865 914 (Australia); Medical Director, Waubra Foundation; firstname.lastname@example.org
(1) – Quote from the Aalborg University web page on the new wind turbine noise regulations:
(2) – Email of February 5, 2012 from Professor Henrik Moller to EPAW:
from Henrik Møller <email@example.com>
Mark Duchamp <firstname.lastname@example.org>
date 5 February 2012 19:56
subject Re: Noise regulations in Denmark
Dear Mark Duchamp
The Danish 20 dB(A) limit for low-frequency noise cannot be compared to normal noise limits because
- it is an indoor limit and not an outdoor limit like usual limits for wind turbine noise
- the limit applies to the limited frequency range of 10-160 Hz – only frequencies in that range are included – the level of the full frequency range may be higher
Without an acoustical background, it may be difficult to understand how much 20 dB(A) 10-160 Hz noise is, but the limit is the same as for industrial noise in Denmark, and it is in the same order of magnitude as the limits in most other countries that have low-frequency limits (the limit may be defined in completely different ways). Most people will easily hear a noise at that level, and some will find it annoying, in particular if it goes on round the clock.
At low frequencies, the perceived intensity, the loudness, increases more steeply above threshold than at higher frequencies. This means that when the level is a few decibels above the 20 dB limit, the consequences are more severe, than if a limit for higher frequencies is exceeded by the same amount. Few people would probably accept 25 dB(A) in their home at night and hardly anyone would accept 30 dB(A). Therefore, measurements must be accurate.
In the new Danish statutory order for wind turbines, the noise is not measured but calculated. This need not be a problem, if the calculations are correct. But they are not.
The main problem is the sound insulation used to obtain indoor levels. The statutory order gives values to be used in the calculation, and these values are based on measurements in 26 Danish houses. Unfortunately, wrong measurements.
Sound at low frequencies varies a lot in a room, and according to the Danish rules for industrial noise, the level should – briefly explained – be measured, where the annoyed person finds it loudest. The sound insulation must be measured the same way in order to be applicable for calculations of indoor levels from the outdoor level. But it was not. The indoor measurement positions were simply chosen randomly and not selected for the high level. Thus the obtained values of sound insulation are too high – by several decibels.
Furthermore, statistical sound insulation values were chosen (from the wrong data) so that 33% of the houses have poorer sound insulation, meaning that the limit may be exceeded in 33% of the cases.
And finally, the calculated values may exceed the limit by a 2 dB uncertainty value. Measured levels from industrial sources are not allowed to exceed the limit.
All these errors sum up to probably not far from 10 dB, which means that the limit is suddenly not 20 but rather 30 dB(A). But the rules are claimed to give the same protection as for industrial sources, which is simply not true.
I hope this helps your understanding.
Professor, Section of Acoustics
Department of Electronic Systems
Fredrik Bajers Vej 7 B5
DK-9220 Aalborg Ø
Phone: +45 9940 8711 (direct)
Phone: +45 9940 8710 (section office)
Phone: +45 9940 9940 (switchboard)
Fax: +45 9940 7510 (section office)
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