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Noise update, 20 November 2008  

Author:  | England, Noise

I am Jane Davis. I live on a farm [Grays Farm] on the Fens in Lincolnshire, England, an area known as South Holland.

May 2006: Deeping St Nicholas Wind Farm – eight 2 megawatt turbines 100 metres tall, 930 metres away (Photograph © julian.t.davis 2007)

May 2006: Deeping St Nicholas Wind Farm – eight 2 megawatt turbines 100 metres tall, 930 metres away
(Photograph © julian.t.davis 2007)

Perceptions of Noise

  • Swish – blade cutting through the air.
  • Ripping /lashing
  • Hum – low frequency drone similar to mains transformer, but uneven.
  • WD40 noise.
  • Background roar.
  • Helicopter noise (aerodynamic modulation – AM) …Whoooomph
  • Enhanced helicopter noise (amplitude modulation of aerodynamic modulation)

Factors That Emphasise Turbine Noise Pollution

  • Shelter – Trees, especially conifers, tend to filter out other noise, making the sound of the turbines clearer.
  • Reflective surfaces – Buildings (especially with steel cladding) reflect the sound, increasing the annoyance and making the enveloping of the area even more complete.
  • Insulation – from other sounds (double glazing, wall insulation, ear plugs etc) leads to greater selection for lower frequency sound pressure waves as they have a much greater ability to penetrate and are practically impossible to protect against in a domestic situation.
  • Wind direction – Most effects are worst when the wind is from a southerly direction, blowing through the wind farm toward our home.
  • Stable air conditions associated with temperature inversion on summer evening, i.e., still air and quiet at ground level but strong wind at 100 metres above ground level.

Extract from South Holland District Council

“It should be noted that the methodology for assessing noise from wind farms is different from other more traditional sources of noise (e.g., loud music). The standard ETSU-R-97 is used for wind farms as opposed to BS:4142 for most other noise sources, meaning that traditional measures of nuisance do not apply.”

Davis-regression-analysis

Davis-AM1

Davis-noise1

Davis-125Hz

Day Date Time Problem “Whoosh” Pulse Hum
1 25/06/2006 15.00 to 23.00 Significant noise and sensations Yes Yes Yes
2 26/06/2006 05.00 – 07.00 and 22.00 – 24.00 11.5 revolutions per min and grinding/rumble heard at night Yes Yes Yes
8 02/07/2006 17.00 – 24.00 Tried to have a BBQ and had to go inside due to noise and vibration – felt by guests also. Difficult to get to sleep. Wind SSE, SSW Yes Yes Yes
21/07/2006 Holiday – Away, throughout holiday all of us slept till at least 9 am. No headaches, or earaches whilst away. Turbines off when we returned home.
15 22/07/2006 04.37 – 07.30 Woken at 04.37, ears pulsing, whoosh, throb and house humming. I cried. Yes Yes Yes.
18 25/07/2006 19.00 – 23.00 Too loud to sit comfortably in garden. Yes Yes Yes
23 30/07/2006 19.30 – 23.01 Could be heard over combines! Yes Yes Yes
25 01/08/2006 04.37 woken by house humming and ears pulsing. Wind from SW, fast and noisy Yes Yes Yes
56 01/09/2006 04.44 woken by house humming and ears pulsing. Wind from SW, fast and noisy Yes Yes Yes
57 02/09/2006 04.38 woken by house humming and ears pulsing. Turbines whooshing and thumping fast and noisy. Eventually got back to sleep by putting fan on facing wall. Yes Yes Yes
61 06/09/2006 04.47 woken by house humming and ears pulsing. Turbines whooshing and thumping fast and noisy. Eventually got back to sleep by putting fan on facing wall. Yes Yes Yes
62 07/09/2006 05.35 – 23.00 Hum very loud and “rattly” Yes

63 08/09/2006 02.00 – 24.00 Woke at 02.00 to go to the toilet, still awake at 03.43. Hum more of a noisy grinding in the background than a hum, and not easy to get back to sleep. Hum and whoosh very noticeable at midnight when we had
visitors!
Yes Yes
64 09/09/2006 04.44 – 23.00 Woke briefly and could hear hum but went back to sleep as had taken sleeping tablets Yes

Transport, environment and health. WHO Regional Publications. European Series No. 89
Disturbed Sleep.
“Noise can cause difficulty in falling asleep, reduction in deep resting sleep. Increased awakenings during sleep and adverse after effects such as fatigue and decreased performance. These effects are avoided if noise levels are kept below 30dB LAeq continuous noise or 45dB LA max indoors. (LAeq values refer to steady state continuous noise. LA max values refer to noise events.)”

So what steps can be taken to protect the residential amenity?

  • Consider what is the difference between sound and noise? Clearly more than the loudness alone. An aircraft is very noisy, but a dripping tap at night can be more than enough to spoil a good nights sleep.
  • ETSU-R-97 just talks about noise as in volume – it does nothing to account for the intrusive character of the noise. So in a rural area 35dB(A) may be as much as 15 dB(A) over background and modulate as well. 43dB(A) (the nightime recommended criteria WILL be too high in a rural area, even with a nearby road!). “A” weighting masks the low frequency element by diminishing it!
  • Spacing is crucial. Spacing between turbines (following current best practice) should be at least 4 × the rotor diameter apart. Between rows of Turbines it should be 10 × the rotor diameter.
  • Whichever turbine is chosen as the model for the EIA then that IS the model and any changes should have a new noise assessment done. Size DOES matter! The relationship between blade length and tower height is critical and crucial to the material effect that it will have on noise and the residential amenity.
  • Distancing from homes/schools etc should be 1.5 miles (in an ideal world) but NEVER less than 1000m, irrespective of whom the inhabitant is going to be!

Download original document: “Noise update, 20 November 2008, Jane Davis, Grays Farm, Deeping St Nicholas

This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

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