environmental statement - Rotherham's Online Application for ...

objects such as trees or walls may surround windows and obscure the
view of the turbines and hence prevent shadow flicker;
during operation, the turbine rotors automatically orientate themselves
to face the prevailing wind direction. This means the turbine rotors will
not always be facing the affected window, and in fact will sometimes be
„side-on‟ to the window. Very little of the blade movement would be
visible during such occurrences and therefore the potential for shadow
flicker is reduced; and
the turbines will not operate for 100% of daylight hours. During periods
of very low wind speed or very high wind speed or maintenance shutdowns,
the rotors do not turn. During such periods shadow flicker is
not possible.
15.13 When considering the above factors a greatly reduced level of impact
occurs.
15.14 If we consider that shadow flicker can only occur during daylight hours and
times of sunshine the maximum occurrence is based upon all hours of
daylight being sunny with clear skies.
15.15 A maximum theoretical occurrence at Ulley Beeches of 125.9 hours per
year can be reduced to 40.3 hours per year when considering that the
Midlands Regional Met Office data gives actual sunshine hours to be 32%
of daylight hours. This figure also does not consider potential marginal
cloud cover diluting any effect.
15.16 A maximum theoretical occurrence at Penny Hill Lane of 104.9 hours per
year can be reduced to 33.6 hours per year when considering the same
methodology.
15.17 The properties at Ulley Beeches and Penny Hill Lane and a number of the
other assessed properties also have a high level of vegetation surrounding
the properties potentially obscuring affected windows when the turbine
rotors are facing.
15.18 Consideration of the above factors leads to the conclusion that the level of
shadow flicker will be greatly less than the predicted levels.
15.19 The possibility that shadow flicker could induce photosensitive epilepsy
has also been considered. It has been demonstrated that the frequency at
which shadow flicker would occur at this site (up to 0.7 hertz per turbine /
cumulative frequency up to 1.4 hertz) is significantly less than the
frequency at which photosensitive epilepsy is usually triggered (between 5
and 30 hertz). While some people are sensitive at higher frequencies, it is
uncommon to have photosensitivity below 2.5 hertz. Published in October
2007, the Onshore Wind Energy Planning Conditions Guidance Note
commissioned by BERR (the Department for Business, Enterprise and
Regulatory Reform) states:
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Penny Hill Wind Farm
Environmental Statement