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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- 55 Cumulative effect It is important that wind energy development development is never perceived to visually dominate. However, given that these landscapes comprise hedgerows and often hills, and that views across the landscape will likely be intermittent and partially obscured, visibility of two or more wind energy developments is usually acceptable. 2(g) Cumulative effect caused by two wind energy developments - although similar in siting and design, the open and full exposure of both developments might be excessive given the fact that it involves an inhabited landscape. 6.9.3 Flat Peatland Key characteristics of this landscape are: • Landscapes of this type comprise a vast planar extent of peatland and have significant potential for future wind energy development; • In their relatively undisturbed and naturalistic state the wet bogs comprise a landcover mostly of heather, wild grasses and bog cotton, as well as patches of coniferous plantation; • Some of these bogs have been harvested for peat and may comprise long parallel ridges of stacked milled peat and deep drains.; • Evidence of human habitation is sparse; • Roads tend to run in straight lines over considerable distances, followed by electricity and/or telephone lines; and • This landscape type is horizontal, open, extensive and also characterised by a sense of remoteness. The preferred approach here is one of large-scale response. The vast visual openness with few, if any, dominant geometric elements provides a certain freedom in the siting and design of wind energy developments. Siting and design guidance for flat peatland Location Wind energy developments can be placed almost anywhere in these landscapes from an aesthetic point of view. They are probably best located away from roadsides allowing a reasonable sense of separation. However, the possibility of driving through a wind energy development closely straddling a road could prove an exciting experience.
- 56 3(a) Random layout - the random spacing is not entirely appropriate to the simplicity of this landscape. 3(b) Staggered linear layout - the rhythmic spacing and layout as well as even profile of turbines create a composition appropriate to the simplicity of this landscape and corresponding to the peat harvesting ridges. 3(c) Grid layout - the rhythmic and regular layout create a composition appropriate to the simplicity of this landscape. Spatial extent The vast scale of this landscape type allows for a correspondingly large spatial extent for wind energy developments. Spacing Regular spacing is generally preferred, especially in areas of mechanically harvested peat ridges. Layout In open expanses, a wind energy development layout with depth, preferably comprising a grid, is more appropriate than a simple linear layout. However, where a wind energy development is located close to feature such as a river, road or escarpment, a linear or staggered linear layout would also be appropriate.
- 57 Planning Guidelines Height Aesthetically, tall turbines would be most appropriate. In any case, in terms of viability they are likely to be necessary given the relatively low wind speeds available. An even profile would be preferred. Cumulative effect The openness of vista across these landscapes will result in a clear visibility of other wind energy developments in the area. Given that the wind energy developments are likely to be extensive and high, it is important that they are not perceived to crowd and dominate the flat landscape. More than one wind energy development might be acceptable in the distant background provided it was only faintly visible under normal atmospheric conditions. Further details in relation to Best Practice for Wind Energy Development in Peatlands are outlined in Appendix 4.
- 58lanning Guidelines 3(d) Cumulative effect of two wind energy developments - this is acceptable where the wind energy developments are limited in spatial extent and are located at great distance apart.
- 59 Planning Guidelines 6.9.4 Transitional Marginal Landscapes Key characteristics of this landscape are: • Comprises something of both mountain moorland and farmland, thus involving a mix of small fields, tight hedgerows and shelterbelts; • May include relatively rugged and rocky terrain, and thus a reasonable degree of spatial enclosure; • Higher ground tends to be wet and boggy. Lower areas are usually cultivated and managed as fields; • Houses and farmsteads are usually fairly common; and • This landscape type bridges the organised and intensively managed farmland and the more naturalistic moorland; The essential key here is one of respect for scale and human activities. These landscapes are often relatively small-scale due to spatial enclosure provided by hills and wind energy developments should respond sensitively to this intimacy. These landscapes are also visually complex due to diverse landform and landcover, as well as houses and power and telegraph poles and lines. Wind energy developments should avoid adding to such complexity due to the risk of creating visual confusion and conflict. Siting and design guidance for transitional marginal landscapes Location As wind energy developments, for reasons of commercial viability, will typically be located on ridges and peaks, a clear visual separation will be achieved from the complexity of lower ground. However, wind energy developments might also be located at lower levels in extensive areas of this landscape type, where they will be perceived against a relatively complex backdrop. In these situations it is important to minimise visual confusion such as the crossing by blade sets of skylines, buildings, utility lines and varied landcover. Spatial extent Wind energy developments in these landscapes should be relatively small in terms of spatial extent. It is important that they do not
- 60 dominate but achieve a balance with their surrounds, especially considering that small fields and houses are prevalent. 4(a) Wind energy development with regular spacing and linear layout - may not be appropriate due to the undulation of land form as well as limited field pattern. 4(b) Wind energy development with irregular spacing and random layout - is more appropriate given the relative undulation of the setting. 4(c) Large wind energy development straddling two landscape character types within the same visual unit - this creates a visual ambivalence and, thus, negative tension between the two character types involved.
- 61 Planning Guidelines Spacing All options are possible, depending on the actual landscape characteristics. However, irregular spacing is likely to be most appropriate, given the complexity of landform and land cover typical of these landscapes, and the absence of extensive swaths of fields of regular and rectilinear pattern. Layout The likely location of wind energy developments on ridges suggests a linear or staggered linear layout whereas on broader hilltops they could be linear or clustered. Grid layouts are less likely to succeed aesthetically unless there is an open continuity of similar landcover. Height In small-scaled enclosed areas, short turbines are preferred in order to avoid their spatial dominance and to ensure visual balance. However where the upper ground is relatively open and visually extensive, taller turbines may be more appropriate. In terms of perceived height, the profile can be even or uneven, depending on the profile and visual complexity of the terrain involved. The more rugged and undulating, the greater the acceptability of an uneven profile provided it does not result in significant visual confusion and conflict. Cumulative effect This would have to be evaluated on a case-by-case basis, but great caution should be exercised. The spatial enclosure often found in transitional marginal landscapes is likely to preclude the possibility of seeing another wind energy development. However, should two or more wind energy developments be visible within a confined setting a critically adverse effect might result, depending on turbine height and wind energy development extent and proximity. 6.9.5 Urban and Industrial Key characteristics of this landscape are: • a predominance of urban complexity, industrial buildings, infrastructure or a combination of these; and • that it is intensively altered and dominated by structures.
- 62 The essential key here is one of rational order and simplicity. Wind energy developments can thematically complement the contemporary technology expression of these landscapes and visually relate to their functional nature. Siting and design guidance for urban and industrial areas Location A wind energy development can be placed sufficiently close to the structures concerned in order to establish a visual relationship but sufficiently distant to ensure a certain autonomy. The wind energy development should appear as a distinct and discrete entity. Spatial extent This should be determined by the spatial extent and height of the existing structures making up the urban and/or industrial context. Generally, therefore, it is likely to be relatively limited. 5(a) Large wind energy development with random layout contiguous to town that can be inappropriate - although an association is achieved between the wind energy development and urban structures as well as infrastructural elements; the wind energy development spatially dominates the hill and town. 5(b) Small wind energy development with regular layout contiguous to town. Regarding its spatial extent, this wind energy development is appropriate to the scale of the hill and town and a thematic association is created with the existing telecommunication towers in terms of technological image.
- 63 5(c) Wind energy development contiguous to industrial buildings with random layout - visual disharmony is created. 5(d) Wind energy development with staggered linear layout contiguous to industrial buildings – rhythmic spacing is appropriate to the industrial and technological image of the context. Spacing Regular spacing will usually provide the greatest possibility of visual integration. A graded spacing, however, could be used to aesthetic effect, depending on how it was composed in relation to the built context. Layout In order to achieve simplicity, a single line or staggered line will most likely be the preferred approach. In the case of an extensive urban and/or industrial complex a slightly deeper plan might be acceptable. Height Where only a very small wind energy development is involved, tall turbines could create a dramatic contrast with existing structures. Otherwise, turbines should be selected so as not to visually overpower existing structures. An even profile would typically be preferred in order to ensure
- 64lanning Guidelines simplicity and reduce the likelihood of visual confusion, but an uneven profile may be acceptable depending on contextual relationships. Cumulative effect In urban areas there is little or no tolerance of more than one wind energy development due to the likely sense of clutter and possible feeling of dominance.
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.