LDP11 Landscape Sensitivity and Capacity Assessment for Onshore Wind Turbine Development

The following notes are summarised from guidelines set out in Scottish Natural Heritage (2012) Siting and Design of Small Scale Wind Turbines of between 15 and 50 metres in height.
Useful guidance is also provided in the following documents. Although aimed at larger windfarm developments, the guidance set out in these documents is frequently transferable and should be considered when designing and siting small scale developments:

• Design Commission for Wales (2012) Designing Wind Farms in Wales
• Scottish Natural Heritage (2009) Siting and Designing Wind Farms in the Landscape

Turbine colour should be chosen to help blend the structure into the landscape. The same colour should be used for all components of the turbine. A very light grey is commonly used because it minimises the visibility of the turbines when they are seen against the skyline, which is how most large scale turbines are viewed. Smaller scale turbines are more likely to be viewed against a vegetated backdrop and may benefit from being a darker grey green colour. In all cases the aim should be to minimise visibility and reflectivity of the turbine components.

Although small scale turbines are likely to have fewer landscape and visual effects than large commercial models, they can still visually dominate nearby landscape features. Identifying the main landscape and visual characteristics of the landscape in which the turbines are to be sited is an important determinant in selecting the most appropriate size. Landscapes with a simple, strong and mainly horizontal form are better able to accommodate taller turbines and large turbine groupings as the height of turbines appears more proportionate to the landscape. Small scale turbines, smaller groupings or individual turbines tend to be better suited to smaller scale, more complex landscapes where there are other features such as buildings, trees or hedges. A useful rule is that turbines should generally be no more than 50% higher than nearby buildings.

Although there is scope to present a small group of turbines as a coherent visual image, this may be difficult where there are other built elements such as buildings, wood poles and masts present with the result that visual conflict can arise. Where possible turbine layout should respond to existing landscape patterns, whether field boundaries, building or vegetation patterns.
In all cases, turbine layout should respect the underlying landform.

Micrositing of turbines often takes place during construction due to unforeseen circumstances such as ground conditions. This can affect the original design concept, particularly the relationship with nearby vertical features such as tress and masts. It is preferable if developers undertake pre-application ground surveys to minimise the requirement for micrositing at the construction stage.

Visual impacts of any ancillary developments and visual conflicts with between turbines and ancillary structures should be minimised by:

• Sensitively siting and designing ancillary equipment and infrastructure (e.g. using local landform, locally appropriate materials, architectural style and colours to more successfully integrate them into their surroundings).
• Using turbines with integral transformers.
• Siting turbines as close as possible to the point of use or grid connection to avoid long sections of overhead power lines or cable runs (more applicable to large scale wind farm developments).
• Utilising existing tracks to avoid tree and hedgerow removal, which may have adverse landscape effects. New tracks if required should follow existing landscape features such as field and woodland boundaries.
• Minimising cut and fill operations.
• Designing fencing or walling to fit the local situation, whilst maintaining the required security.
• Identifying locations for new tree and shrub planting to provide long term screening.

This sensitivity and capacity study provides the basis for identifying the key landscape characteristics of the site and the wider area. It also identifies the sensitivity of the landscape to turbines and any special qualities which should be protected. However, this is a strategic study and in all cases turbine applications (large or small scale) must be considered on their individual merits and detailed analysis is required to fully appreciate the nature of the development, site and its surroundings.
Impacts on landscape character are likely to be related to:

• Scale of the landscape – whether it is small or large and whether the proposed turbines are of an appropriate scale.
• Influence on the tranquillity of the landscape – turbines creates movement, the amount depending on the particular model.
• Settlement pattern – turbines should be carefully sited in relation to existing buildings.
• Topography – turbines can dominate small scale or intricate landform if not carefully sited.
• Skylines – turbines can affect the simplicity of skyline or ridges even if located below such features.

Rural areas which are particularly valued for their remoteness or wildness can be affected by the introduction of turbines, although this is less likely to be the case if the turbines are located close to farms or other existing buildings. However, incremental erosion of the special qualities of remoteness and wildness should be avoided.
Some locations close to centres of population are valued as an important recreational resource and have a sense of wildness even though they are close to urban areas. Locating turbines in these areas should be very carefully considered.

All landscapes are valued but this report identifies landscapes which are designated for their international, national or regionally valued qualities. Again, however, this is a strategic study and in all cases turbine applications (large or small scale) must be considered on their individual merits and detailed analysis will be required to fully appreciate the nature of the development, site and its surroundings and effect on any locally designated or higher value landscapes.

Landform
Smaller turbines have more potential to utilise landform (often in conjunction with vegetation) to help lessen their visual impact than larger scale commercial models.

As the viewer’s eye tends to be drawn towards the skyline, turbines should be set back from ridges and skylines to reduce their visibility within the wider landscape. Where siting on a skyline is unavoidable then the aim should be to retain a balance of skyline features or to provide a new focal point in an otherwise featureless skyline.

Siting of turbines on distinctive or prominent summits or skylines should generally be avoided. Shallower side slopes or gently undulating landform below ridgelines should be selected where possible.

It is often preferable for wind energy developments to be grouped upon the most level part of the site so the development appears to be less visually confusing when viewed from different elevations and directions.

Landscape Pattern
Turbines can be sited to reflect patterns in the landscape, for example field and woodland boundaries or coastal edges. Conversely, care must be taken not to site turbines so that they conflict with patterns in the landscape.

Groupings of turbines can affect how they appear in the landscape. For example three dispersed turbines could be grouped to form a single feature in a visually complex landscape, whilst in a larger scale landscape, a single turbine with the same generating capacity may be preferable.

Multiples of turbines of a smaller size are most likely to be preferable in more lowland landscapes, where there are many other scale indicators.

Focal Features
Turbines are likely to become focal features in the landscape particularly when new or unfamiliar designs are introduced. Care is required to ensure that they do not cause visual conflict or competition with other focal points. The siting of turbines should therefore be carefully considered to protect views to and from important landscape and cultural heritage features and their wider setting.

Turbines can highlight features which would otherwise be hidden. For example a turbine next to a farm could draw attention to its presence when the farm itself is hidden by buildings or trees.

Perspective
The size of features in the landscape influences the perception of perspective. For example if larger turbines are seen in front of smaller ones, the smaller ones can appear further away than they actually are. Conversely, if smaller turbines are in front of larger ones, the larger ones can appear further away.

Relationship with Settlement and Urban Landscapes
Turbines should be carefully located in relation to nearby settlements, buildings and other structures. In sparsely settled rural landscapes, turbines should be located to existing buildings or structures.

Views to/from, or on the approach to settlements (including dispersed properties) should be carefully considered when siting wind energy developments. Turbines should be located in the least visually prominent location. The type of turbine may be influenced by its proximity to settlement – a two bladed turbine is likely to visually integrate better with a busy urban setting than a calm rural location.
Turbines should be sited to minimise impacts on public viewpoints, roads and public rights of way.

Woodland & Trees
Although trees and woodlands can cause turbulence which interferes with the efficiency or longevity of turbines, in some locations there may be the opportunity to screen small scale turbines close to trees and tall shrubs. Care should be taken to site turbines so that they do not visually dominate or compete with prominent vegetation such as parkland tree, trees on knolls, avenues etc.

Turbines should be located without the need to fell trees and woodlands particularly where they are important features in the local landscape.

Seasonal variation in leaf cover should be considered when using trees to screen turbines as should felling and restocking regimes when considering commercial forestry.

Cumulative consideration of new turbine developments should include simultaneous, sequential or combined views.

Groups of micro turbines can be prominent in some locations, by drawing the eye to their rotating blades. Rotation speeds vary considerably between small and larger bladed turbines, which if viewed together can create visual disturbance and clutter, rather than balance. Variations in rotor blade diameter should therefore be avoided.

Multiple small scale developments can dominate the landscape. Turbines should not create visual clutter with existing built development and vertical structures such as high voltage overhead power lines and communications masts. Man-made structures do not all share the same characteristics of scale, shape or form. Visual clutter and cumulative impact can occur when turbines are placed too close to vertical structures of dissimilar character such as electricity pylons and communication masts. To avoid this consider the following principles:

• Avoid inconsistent turbine height, layout and design between multiple wind energy developments.
• Consider associating particular types of turbines with specific situations. For example turbines on lattice towers in rural situations and turbines on tubular towers in urban situations. This helps create some local distinctiveness.
• Identify opportunities to lessen intervisibility between multiple developments – intervening landform and forestry are all useful in this respect.

Turbines should be carefully sited in relation to important viewpoints. To ensure a consistent spatial relationship between small scale turbines and other forms of development, especially tall structures such as pylons and masts, where possible ensure that developments are visually linked with landscape features such as forestry, farms, skylines or contours.

Smaller turbines when seen in combination with large turbines can create a confusing visual image. This can be lessened by:

• Using the same type of turbines design where more than one scale is visible.
• Using turbine layouts of a similar arrangement where more than one turbine group is present.
• Avoid situations where turbine rotary speeds are significantly different.

Onshore turbines can create visual clutter and confusing perspective when seen in combination with offshore turbines. This should be avoided wherever possible.

The perception of an area can be altered by introducing small turbines between clusters of windfarms which creates a visual link between all of the developments. Where site analysis indicates that visual separation is desirable, the gap between developments should be maintained.