Ministerial guidelines
Wind Energy Development Guidelines
Siting, design, noise and shadow flicker for wind farms. A revised draft was published for consultation in 2019.
Department of the Environment, Heritage and Local Government · June 2006 · 119 pages
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- 35 Planning Guidelines Chapter 6 Aesthetic Considerations in Siting and Design 6.1 Introduction The primary purpose of this chapter is to provide guidance to planning authorities on decision-making in relation to the siting and design of wind energy developments in the landscape when assessing applications for planning permission. The guidance provided is indicative and general. It typifies ‘best fit’ solutions to likely situations and is thus, proactive. It does not suggest that wind energy developments are appropriate in any given situation. These questions can be informed and/or qualified by the values people attach to landscape and by evaluating their sensitivity through the sieve analysis described in Chapter 3 on the development plan process, or otherwise at a strategic and/or project specific level. The highest standards of siting and design for a wind energy development, as presented in this chapter, should be expected where the sensitivity of the landscape is high and the locations from where it is viewed are critical. Where a wind energy development is close to and visible from an area of high sensitivity, it should be designed to achieve similar standards as viewed from key viewpoints in that area. Particular landscapes of very high sensitivity may not be appropriate for wind energy development The first section of this chapter deals with the general principle of landscape siting and design of wind. It comprises a series of line diagrams that are conceptually illustrative of typical problems and solutions as viewed from a fixed idealized location. These diagrams are presented under the following headings: • Siting • Spatial extent and scale • Cumulative effect • Spacing of turbines (regular, irregular, graduated)
- • Layout of turbines (single line, staggered line, clustered, grid) • Height of turbines (tall, medium, short)12 The second section considers how these principles can be best applied within different types of landscapes. Guidance is also given in relation to associated development, including substation compounds, access tracks and fencing. A more detailed elaboration of the tools required for landscape impact assessment of wind energy development proposals is provided in Appendix 3. 6.2 Aesthetic Considerations While many issues in relation to wind energy development can be assessed in quantitative terms, aesthetic considerations are more subjective and qualitative. They represent, nevertheless, some of the most critical issues in relation to wind energy development, and can be discussed with reasonable objectivity. Considering wind energy development in respect of the following concepts can be helpful in the creative and critical analysis of aesthetic issues in relation to wind energy developments, and can help in achieving reasonable objectivity on the subject: • Conventional visual aesthetic, such as compositional balance and harmony, rhythm, positive tension, aesthetic order and clarity, and including perception of wind energy developments as sculptural elements in the landscape. • Positive association, where, for example, a wind energy development relates thematically to modern structures in terms of form, function and/or operation, perhaps even affirming an identity in a given landscape. 36lanning Guidelines 12 The notion of what constitutes tall, medium and short turbines will change over time with technological advances and thus a shift in turbine height relative to capacity. In 2005, less than 60m to blade tip are considered short, 75-100m medium and over 100m tall.
- • Symbolism, whereby a wind energy development represents or is a public sign for technological efficiency, progress, environmental cleanliness and utility. These concepts provide the conceptual basis necessary for practical guidance on the relationship of wind energy developments to typical landscapes and landscape characteristics and can be applied to key landscape siting and design issues. 6.3 Siting of Wind Energy Developments 6.3.1 Location The elevation and position of a wind energy development in the context of the character and feature of the landscape. Issues to be addressed include: • Consideration of lower ground, where feasible, may be necessary in sensitive landscapes, but otherwise location on ridges and hilltops may be visually acceptable; • Consideration of prominent landcover and structures, or features to which a wind energy development can provide a visual counterbalance; • Management of visual exposure from viewing locations in respect of the sectional profile, striving in so far as is practicable; to achieve full turbine exposure from sensitive key viewpoints, as the perception of complete turbines is more aesthetically pleasing than stunted turbines; • Taking advantage of the possibility of a relationship between a wind energy development and, say, an urban settlement; and • Avoiding the creation of visual confusion and spatial dominance where landscapes are already cluttered, but take advantage of a moderate amount of visual absorption that might be provided by existing structures and/or infrastructure. 37 Planning Guidelines
- 6.3.2 Topographic Profile A wind energy development should be located so as to optimise the aesthetic qualities of the surrounding landscape and those of the wind energy development itself. It should, therefore, respond to topographic profile, achieving visual balance and accentuation of landform. Fig 1: Wind energy development located on a peak Fig 2: Wind energy development located in saddle between peaks – framing and, thus, accentuation achieved. 6.3.3 Sectional Profile Fig 5: Wind energy development partially screened behind crest where screening visually stunts towers. 38Planning Guidelines Fig 3: Wind energy development located above a concave slope, providing full visual exposure. Fig 4: Wind energy development located above & behind convex slope, partially screening turbines from view.
- 6.3.4 Composite Relationships Large entities contiguous to a wind energy development may or may not result in visual balance. In diagram below, a forest stands in profile, creating a visual counterbalance to the wind energy development. This assumes the typical practice of replanting commercial plantations after harvesting. Fig 6: Wind energy development in visual harmony with forest. Large entities such as power lines and towers, agricultural buildings, houses and roads may create a context that visually absorbs a wind energy development, especially in farmland (visual absorption capacity), though in more sensitive upland situations this could result in visual confusion. However, visual complexity as well as image and/or thematic association with industrial structures, for example, can help to assimilate a wind energy development where it becomes just one more element in the landscape. Fig 7: Wind energy development located in a landscape of complex visual composition resulting in visual confusion. Where the wind energy development is relatively close and above a small urban node, it should respect the scale of its setting and avoid spatial dominance. 39 Planning Guidelines
- Fig 8: Wind energy development located contiguous to an urban centre. 6.4 Spatial Extent and Scale Spatial extent is the area covered by a wind energy development, reflecting the number of turbines involved and their spacing. The spatial extent of a wind energy development should be balanced and in scale with its landscape context. This involves consideration of the perceived size (extent and height) of landform, landcover and structures relative to the wind energy development. Many turbines viewed at close proximity in a spatially enclosed area, such as hilly mountain moorland or farmland area will be large while a few turbines on open moorland will be regarded as small.13 Fig 9: Wind energy development is too limited in spatial extent relative to the scale of its panoramic setting. Fig 10: Spatial extent of wind energy development is more appropriate regarding the scale of its panoramic setting. 40lanning Guidelines 13 The term ‘size’ is deliberately avoided here as it is usually used within the industry to indicate the capacity of turbines to generate electricity (measured in megawatts).
- 6.5 Cumulative Effect Cumulative effect is the perceived effect on the landscape of two or more wind energy developments visible from any one place. • A landscape of complex landform and landcover provides a greater possibility of screening for more than one wind energy development. • Similarity in the siting and design approach is preferred where a number of wind energy developments are located in the same landscape character area, particularly within the same viewshed. However, an alternative approach where a particular aesthetic effect is sought may be acceptable. • Different wind energy developments can appear as a single collective unit if located near each other. • It is preferable to avoid locating turbines where they can be seen one behind another, when viewed from highly sensitive key view points (for example, viewing points along walking or scenic routes, or from designated views or prospects), as this results in visual stacking and, thus, confusion. This may not be critical, however, where the wind energy development to the rear is in the distant background. 41 Planning Guidelines Fig 11: Wind farm is too spatially extensive relative to the scale of the hill. Fig. 12: Spatial extent of wind farm is more appropriate relative to the scale of the hill.
- Fig 13: Wind energy developments dissimilar in terms of spatial extent, spacing and layout in different landscape types but within the same viewshed. Wind energy developments within relatively close proximity to one another, while in different landscape character contexts, may be so close as to be within the same visual unit and, therefore, should involve the same siting and design approach. 6.6 Spacing Spacing concerns the position of turbines relative to one another and the gaps between turbines. • Regular spacing is more appropriate for wind energy developments in landscapes of clear and orderly landcover pattern or unenclosed flat landscapes. • Irregular spacing is more appropriate in landscapes of varied landcover pattern or hilly and/or rugged landscapes. • Graduated spacing of turbines is acceptable for wind energy developments where accentuation of a landscape feature or the creation of a sense of climax is sought. • Generally, spacing should be of a uniform type in any given wind energy development, rather than a mixture. • Some flexibility in spacing should be integral to a planning permission to allow for necessary on-site fine-tune adjustment of turbine placing due to such considerations as geological support for foundation or archaeological remains, etc (see paragraph 7.3 and 7.4). 42lanning Guidelines
- 43 Planning Guidelines Fig 14: Wind energy development with regular spacing of turbines – a simple and obvious rhythm. Fig 15: Wind energy development with irregular spacing of turbines – no obvious rhythm, i.e. non-repetitive. Fig 16: Wind energy development with graduated spacing on a hillside - attractive in terms of accentuation of ascent and sense of climax. 6.7 Layout Layout concerns the position of turbines, providing the overall form or configuration of the wind energy development and its perceived density or complexity. • Generally, layout should be of a uniform type, whether a single line, staggered line, splayed line, random or grid, rather than a mixture; • The creation of a “visual stacking” effect from a sensitive viewpoint should be avoided; • A circular / oval cluster or linear layout would be appropriate on hilltops; • A linear or staggered linear layout would be appropriate close to a road or other such linear features; and
- 44lanning Guidelines • A random or grid layout would be appropriate on a vast open landscape. Fig 17: Plan and view of single line layout. Fig 18: Plan and view of staggered line layout. Fig 19: Plan and view of splayed linear layout. Fig 21: Plan and view of grid layout. Fig 22: View of linear layout on a peak. Fig 23: View of linear layout in response to a road, shoreline or cliff. Fig 20: Plan and view of random layout
Source Department of the Environment, Heritage and Local Government: Wind Energy Development Guidelines (June 2006) · Licence the publisher's termsText read from the publisher’s PDF; tables, maps and drawings do not survive as text, and page numbers are the PDF’s (its first page is 1). Check the original before relying on a passage.