Non Technical Summary - Partnerships for Renewables

Shadow Flicker – Chapter 14 continued >
of modern wind turbines such as those proposed at Camp Hill
rotate at a speed of less than 20rpm so, as a turbine has
three blades, in any one minute there will be a maximum of
60 blade shadows equating to a rotational speed of 60rpm.
This equates to 1Hz which is below the 2.5Hz minimum
required to trigger epilepsy. This information is derived from
Government and independent research as detailed in the ES.
The duration of potential shadow flicker has been
accurately modelled in the ES using software which uses
the known position of the sun in the sky for every minute
of the year. Assuming worse-case conditions (sufficient
daylight, correct alignment of the blades and no obstacles
between the window and the turbines) potential shadow
flicker effects were predicted in the ES at some thirtyfive
residential properties/prison accommodation blocks
and, of these, fifteen were assessed in detail since some
properties are located on the same street and adjacent
to each other i.e. a representative sample was analysed
further rather than every property individually. The highest
predicted level of shadow flicker effects for properties was
an average of 49 minutes per day up to 56 days per year.
The maximum predicted occurrence of shadow flicker
throughout the year is 45 hours. This assumes that the
sun is always shining during daylight hours and there is no
screening or obstruction i.e. from trees, hedges, structures,
etc. Realistically however, in the UK, the sun shines for
approximately one third of daylight hours and, if this is
taken into consideration, the likely effect would significantly
reduce to a maximum average of 17 minutes per day on up
to 56 days per year and the maximum predicted occurrence
of shadow flicker throughout the year would be 15 hours
per year.
Further Information
Printed copies of the non-technical summary and ES
(including figures and appendices) may be obtained from
Partnerships for Renewables, Station House, 12 Melcombe
Place, London, NW1 6JJ. The non-technical summary is
available free of charge and a limited number of hard copies
of the Environmental Statement are available for £500 per
copy. A limited number of CDs/DVDs containing PDF files of
the Environmental Statement are available for £15 per CD/
DVD. Alternatively, these electronic files can be downloaded
from http://www.pfr.co.uk/camphill.
Copies of the Environmental Statement may be viewed at
the following location during opening hours:
Isle of Wight Council
Council Offices
Seaclose
Fairlee Road
Newport
Isle of Wight
PO30 2QS
Where shadow flicker effects occur at properties mitigation
measures will be put in place which could include planting,
garden screening or operational controls on the turbines by
way of a programmed shut down.
The shut down system would use a device to measure the
intensity of sunlight occurring at a particular moment and
would use this, together with time and date information
programmed into the device, to determine whether shadow
flicker will occur. If the intensity of sunlight is above that
which is required to cause a shadow flicker effect and
the time of day corresponds with a predicted effect the
automatic programme would shut down the wind turbine
until the time period when shadow flicker may occur has
passed and the turbine would re-start automatically.
If required the available mitigation which is normally
secured via a planning condition would result in no
significant effects resulting from shadow flicker.
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