Posted By: Gavin_AIf average is used, then it means around 50% of the time the background noise will be quieter than this, so 50% of the time the actual level of disturbance experienced will be more than intended to be allowed even if the actual noise level from the wind farm is within the limits set.

Depends on which average is used, that would be true for median, not for mode or mean.

Posted By: SteamyTea

Posted By: Gavin_AIf average is used, then it means around 50% of the time the background noise will be quieter than this, so 50% of the time the actual level of disturbance experienced will be more than intended to be allowed even if the actual noise level from the wind farm is within the limits set.

Depends on which average is used, that would be true for median, not for mode or mean.

that's why I used the word 'around', as in not exactly, but somewhere in the region of.

When someone is financially involved in a wind farm development (e.g. farmer leases his fields) ETSU-R-97 allows that the noise they may suffer can be higher than for neighbours who are not financially involved. The noise limit can be 45 dB rather than the standard 40 (day) or 43 (night) dB.

What are your views on the situation where there are multiple wind farms which might all affect the same property with a mix of involvement and non-involvement?

In theory 45 dB is allowed to be generated by one wind farm but only 40dB by another next to it. How could this be applied in practice (especially across separate planning conditions) given that ETSU-R-97 states that noise limits must take cumulative impacts of turbine noise into account?

It just goes to illustrate the nonsense that ETSU-97 is. A night time noise limit more than the day time, 40dB when the background is 35dB. If it were a factory, it would never be tolerated. But Ted's question can be answered same as if two factories next door to each other, one with a 40dB limit and the other with a 45dB limit. You have to measure when both are on, then stop one whilst another measurement is taken, then stop the other, etc, etc. Not easy, who pays for the downtime, lots of other issues. That's why such situations rarely get resolved. One always blames the other unless the noise is attributed to an obvious source like a new piece of plant or bearing failure.

Ted,
Yes I see your point and I agree totally. However, I can't see Brechfa West agreeing to a 23.6 dB limit - even when that's still probably around the night time background!

djh - yes, but each wind farm operator would just say " it's not me, I'm within my 43dB limit". ..and the arguments roll on whilst the accumulative limit is breached. It would never get resolved. That's why you must have the lower limit for the second wind farm.

Exactly!

It's not just noise is it. Health issues have been coming out of the woodwork for a while now. See new thread.

It's an interesting paper but they didn't actually try to measure noise levels or examine/test people to see if there was a link between noise and health or look at health effects in animals that presumably can't be influenced by articles on the web.

Perhaps, but even people who like them and land owners have reported problems despite the gagging orders the developers impose.

Just an example..

http://au.news.yahoo.com/latest/a/-/latest/16369441/couple-claim-windfarm-health-issues/

"A South Australian couple claims they are suffering horror side effects from windfarms, and say poor health is not worth the financial compensation received for having turbines on their land."

Time for some double-blind tests, methinks.

E.g., person reported as susceptible spends a day or two in a house adjacent to a turbine but shielded from direct sight of it with the turbine either operating or not selected at random. Needs to be repeated quite a few times with different people, turbines, houses, etc.

But that's the point of a proper double-blind experiment: unless there's outright cheating the prejudices of the experimenters shouldn't affect the results. In particular, the person coding/scoring/observing the subject and the outcome shouldn't know whether the turbine was operating or not. Only when you've got hard numbers which are not subject to bias should comparison with the input data (wind turbine state) be made.

From: MAS Environmental <mail@masenv.co.uk>
Date: 26 November 2013 12:15
Subject: Wind Farm - Amplitude Modulation controls finally accepted at 3dB
To:


Dear all,

Recent research presented at three Planning Inquiries that were conducted in September, October and November (Starbold, Bryn Lleweln and Shipdham - decisions awaited) have hopefully exposed the misconceived arguments made by the Industry's acousticians' which have successfully avoided controls over wind farm noise impact for many years.

After more than 4 years of smoke screens, obfuscation and erroneous objections raising unrealistic concerns and placing barriers in the way of necessary controls over the wind farm noise called "Excess Amplitude Modulation", industry acousticians have finally admitted a planning condition is "necessary" and "reasonable". Excess AM is now shown to be neither rare nor only causing minor effects as claimed over the last few years, arguments that have successfully blocked planning controls leaving many communities exposed to serious noise impact. Research by ourselves and the Japanese have exposed this as a common and serious problem.

Dr Matthew Cand of Hoare Lea is part of the Renewables UK research team on EAM who were due to report their findings over 2 years ago but have continuously deferred this. He finally admitted after 2 hours of cross-examination, when being questioned over the need for a condition at the Shipdham Inquiry last week, that one was both necessary and reasonable. Dr Cand was also questioned over the Den Brook condition metric which was accepted in 2009 but rejected ever since and that was formulated by MAS Environmental with a 3dB(A) EAM limit. This has been subject to widespread industry attacks over the last four years, leading to its rejection by planning inspectors ever since the Den Brook decision. In response Dr Cand said "If I had to pick a number I don't think 3dB(A) is a bad number". In effect the Renewables UK research must support what we found four years ago.

These admissions follow years of unpublished work by Renewables UK, coupled with statements that no one knows the appropriate level. In September at the Starbold Inquiry arguments that the Den Brook condition was triggered by extraneous noise were dropped by the appellants and they accepted it was an incorrect argument. Following the Bryn Llewelyn appeal in October 2013 Dr Jeremy Bass of RES, the main opponent of the Den Brook condition said during a meeting:

"foolishly ... we went along the industry line that amplitude modulation is rare". He accepted the argument that it can be dealt with by statutory nuisance was wrong. He continued "I think that argument is completely exploded by the weight of evidence presented by Mike Stigwood in particular .... we are in a difficult position now ... the landscape has changed and I suspect .... in the future developers will no longer try the argument that AM is rare".

It is hoped decision makers will no longer receive erroneous arguments about the control of EAM and that conditions following the Den Brook metric are now applied to all future consents. There also needs to be a mechanism developed by Government for applying it to existing wind farms. Emerging evidence from the Japanese studies suggests a stricter limit may arguably be necessary but at the present time it is safe to consider the Den Brook metric as a means of controlling wind farm noise.

We also hope decision makers will now exercise particular caution with respect to arguments made by wind industry acousticians and that those who raise concerns over wind farm noise, in the main, do so legitimately.

If anyone seeks further information on appropriate forms of control of this common noise problem they can visit our website at www.masenv.co.uk for more information or email us direct.

Kind regards Mike Stigwood

Thanks Joiner and Ted.