Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
14.5 Cumulative Effects
14.5.1 Potential cumulative effects have been considered, however no further cumulative effects have
been identified. The nearest wind farm to the proposed wind energy development is located at
approximately 6km.
14.6 Mitigation
14.6.1 Shadow flicker events predicted to occur, will be reduced in practice, taking into account
various factors including times when turbines are not turning, cloud cover and the direction of
hub and rotors towards the receptor i.e. effect will be minimised when turbine is not facing the
receptor ‘square-on’. The calculations detailed in Table 14.2 predict the worst case scenario at
the receptors.
14.6.2 If shadow flicker effects occur in practice at a particular property, it does not immediately follow
that additional mitigation is required. Such effects would need to occur in a room that was
occupied at the time of occurrence and for the duration that caused a nuisance. For example,
if the effect was predicted to occur for a three week period in the early hours of the morning in
a room unlikely to be occupied with each occurrence lasting just a few minutes, then it is
unlikely that additional measures would be needed.
14.6.3 Once the location and turbine parameters are defined, the periods during which shadow flicker
can occur are predictable. Therefore, if following a complaint to the planning authority and
following investigation by the operator, shadow flicker is confirmed to result in a loss of amenity
at any location, then mitigation would be implemented. Effective forms of mitigation will vary to
suit the specific circumstances but may include: window screening (with shutters, curtains or
blinds); planting or constructing garden screening; or operational controls.
14.6.4 In the case of operational controls, a specific turbine (or turbines) could be programmed to
shutdown at specific times when the sun is bright enough to cast nuisance shadows. Solar
sensors will be fitted on the nacelles of the turbines to monitor the light intensity to facilitate this
function. There is not specific UK guidance regarding what level of light is sufficient to cause a
shadow flicker event. However, the actual light level which would trigger a turbine shutdown
can be manually configured on-site following installation, to reflect local conditions.
14.6.5 A planning condition provides an appropriate form of mitigation to ensure that any complaints
will be investigated in a reasonable timescale and that the rectification of any shadow flicker
problem that is substantiated will be implemented promptly and effectively.
14.7 Residual Effects
14.7.1 Following adoption of the proposed mitigation measures it is unlikely that any property within a
distance of 10 rotor diameters (900m) will experience shadow flicker effects. Effects are
unlikely to occur beyond this distance.
14.7.2 A programme of monitoring will ensure the effectiveness of the proposed mitigation and allow
for it to be adapted to allow for any inaccuracies in the calculation.
November 2010 Chapter 14 Page 15
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