Supporting Documentation - Renfrewshire Council

3.8 Vibration
The Dunlaw study was designed to measure effects of extremely low level vibration on one of the quietest
sites (Eskdalemuir) in the world, and one which houses one of the most sensitive seismic installations in
the world. This study was designed to measure effects of extremely low level vibration at Eskdalemuir,
housing. In a rebuttal to the negative press coverage which followed publication of the report, it was
stated that while it is technically correct that vibrations can be picked up as far away as 10km, to give this
impression that they can be felt at this distance is misleading.
Vibrations at this level and in the frequency range will be available from all kinds of sources such as traffic
and background noise and are certainly not confined to wind turbines. To put this level of vibration into
context, they are ground vibrations with amplitudes of about one millionth of a millimetre. There is no
possibility of humans sensing the vibration and absolutely no risk to human health. The department of
trade and industry (DTI) by ETSU carried out a study into low frequency noise and vibration from wind
farms. The study conclusions were that vibration levels attenuated rapidly with distance; 100m from the
turbine, vibration levels were 10 times lower than those recommended for human exposure in critical
buildings; there was no clear increase in vibration with wind speed and tones above 3.0Hz were found to
attenuate rapidly with distance.
Due to the distance to the nearest residential property it is concluded there will be no constraints to
development and no need for any further assessment.
3.9 Shadow Flicker
Wind turbines, like all tall structures, cast shadows. The shadow length varies depending on the sun’s
altitude, geographical position, the time of day, time of year and rotor diameter. As the sun passes
behind the blade of the wind turbine a moving shadow is cast over the neighbouring properties. If this
shadow passes over a window, the light in the room will decrease and increase as the blade rotate
creating a flick-on flick-off affect know as shadow flicker.
Information specific to shadow flicker may be found in “Planning for Renewable Energy: A Companion
Guide to Planning Policy Statement PPS22 Renewable Energy.” The Companion Guide states that
‘Although problems caused by shadow flicker are rare, for sites where existing development may be
subject to this problem, applicants for planning permission for wind turbine installation should provide an
analysis to quantify the effect.’
Therefore, in order to quantify this effect, a Shadow Impact Assessment has been carried out in
accordance with the above policy which states that shadow flicker effects have been proven to occur only
within 10 rotor diameters of a turbine and the area within 130 degrees each side of north. Areas outwith
this are not affected as there is no path between the sun and the turbine which could cause shadow
flicker. Additionally, in situations where there are properties within the shadow flicker area, they will only
be affected if there are windows or openings facing the turbine.
The turbine rotor in this assessment is 27m diameter. The study area is therefore limited to a 270m
radius from the proposed turbine. As illustrated in the Turbine and Constraints drawing contained in
Appendix D, there are no dwelling houses, workplace or community facilities within the area which can be
affected. It can therefore be concluded that shadow flicker will not be an issue for this site.
Waterman Group, Renewable Energy, 2/4 Canning Street Lane, Edinburgh, EH3 8ER T:0131 221 7020
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