3.9 As a general rule for most rural areas of Scotland:
– A single colour of turbine is generally preferable;
– The use of graded colours at the turbine base should be avoided;
– A light grey colour generally achieves the best balance between minimising visibility and visual impacts when seen against the sky;
– The use of coloured turbines (such as greens, browns or ochres) in an attempt to disguise wind turbines against a landscape backcloth is usually unsuccessful;
– Paint reflection should be minimised;
– For multiple windfarm groups or windfarm extensions, the colour of turbines should generally be consistent; and
– Precise colour tone and the degree of paint reflectivity should be specified at the application stage.
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3.10 It is preferable for wind turbine transformers to be housed within the turbine towers, to minimise the number of elements and visual complexity of a windfarm scheme. However, where transformers are housed separately near the base of turbines, the colour of their housing requires careful consideration. This should be site specific, relating to the surrounding land cover, not the wind turbines, as transformers are rarely viewed against the skyline. Such an approach ensures that their visibility is reduced, and they are seen as a separate element to the wind turbine so that they are less likely to detract from the simplicity of its form. Browns, khakis and ‘earth’ colours are generally the most successful colour choices for transformers, with greens often appearing too bright.
Turbine lighting
3.11 In some locations it may be necessary to light wind turbines for reasons of civil or military aviation safety. Such lighting, typically at the top of the tower of the wind turbine, may appear prominent in night views and may be incongruous in predominantly un-lit rural areas. Where lighting is necessary, this should be designed to minimise landscape and visual impacts whilst satisfying health and safety or navigation requirements. This may, for example, be achieved by incorporating shields so that the lights can only be seen from above.
3.12 As yet there has been little experience of lighting turbines in Scotland. However, it is likely to become more of an issue as more sites are being explored within flight paths. SNH is collating information to develop our understanding of these impacts with a view to developing further guidance in due course.
Turbine size
3.13 As wind energy technology has developed, larger wind turbines have become available. Currently machines typically consist of 60 – 100 metre high towers with blades of 40 metres or more, so their overall height to blade tip is typically 100 – 140 metres, although some higher turbines are now available. Longer blades result in a greater rotor area and, combined with the fact that they will likely extend upwards into higher wind velocities, their wind capture and energy production tends to be proportionally larger than smaller turbines.