3.14 Choice of turbine size is an integral part of the design process of a windfarm in relation to key landscape and visual characteristics. Identification of the key landscape characteristics, their sensitivity and capacity to accommodate change
will inform this. Generally speaking, large wind turbines may appear out of scale and visually dominant in lowland, settled, or smaller-scale landscapes, often characterised by the relatively ‘human scale’ of buildings and features. On the other hand, the longer blades of larger turbines often have slower rotation speeds and this can be less visually distracting than the faster speeds of smaller blades.
Increase of wind turbine height is not very noticeable within moorland landscape, due to lack of size indicators; nevertheless, there may be a threshold at which larger wind turbines no longer seem to directly relate to the local area of moorland but, rather, relate more closely to the neighbouring high mountains
The size of wind turbines is clearer within a distinct landscape pattern that includes definite scale indicators. Although older/domestic wind turbines may relate to the scale of buildings, most commercial wind turbines commonly used now, over 60m in height, will seem to dominate elements of landscape pattern. There may be, however, a threshold in some landscapes at which a larger wind turbine would no longer seem associated with the underlying landscape pattern and seem ‘elevated’ above it, by appearing to relate to larger components.
3.15 Wind turbine size is also a key issue in upland landscapes that are viewed against or from landscapes which are more intricate in scale and pattern, or where it is otherwise difficult to discern scale and distance. By illustrating the scale of an
upland landscape, wind turbines may seem to compromise the perceived expansive nature of some of these areas.
3.16 As the experience of different landscapes varies greatly, it is not appropriate to provide strict guidelines on turbine sizes that should be used for particular landscapes. Site-specific assessment and design is essential for each
development proposal.
3.17 It is understood that procurement of ‘smaller’ turbines is becoming increasingly difficult as turbine manufacturers move towards larger models. However, some smaller models remain available and may be particularly appropriate near or
adjacent to an existing development comprising of small turbines as well as in smaller scale landscapes. It is important to highlight that a ‘one size fits all’ approach will not respond to the great variation of landscape scale and windfarm
requirements; thus it is important that a market for different sizes of wind turbines, including medium and small sizes, is maintained.