CUMULATIVE EFFECTS OF WINDTURBINES

A GUIDE TO ASSESSING THE CUMULATIVE EFFECTS OF WIND

ENERGY DEVELOPMENT

ETSU W/14/00538/REP

ContractorLandscape Design Associates

The work described in this report wascarried out under contract as part of theNew and Renewable EnergyProgramme, managed by ETSU onbehalf of the Department of Trade andIndustry. The views and judgementsexpressed in this report are those of thecontractor and do not necessarily reflectthose of ETSU or the Department ofTrade and Industry.

First Published 2000 Crown copyright 2000

THE CEWT PROJECT

The following individuals participated in the consensus-buildingprocess which underpinned the preparation of this guidance.Their attendance at workshops, and the opportunity given tocomment on the text, should not, however, be taken to indicatethat those involved necessarily subscribe to all of the views setout in the report. Whilst an absolute consensus on every detailproved not to be achievable, the guidance aims to strike anappropriate balance. Increasing awareness amongst stakeholdersof where a lack of consensus persists has in itself been useful.

Name Organisation

Simon BilsboroughLillian BirchPhil BlackFrancis ComynNeil CrumptonMartin DoddsDavid J EllisJack EllerbyDavid FarrierPaul GillDavid GlasonNick GoodallColin GoodrumKay HawkinsPeter HinsonRebecca HughesSimon LawrenceTed LeemingLily LingeRussel MarshLilli MatsonAmanda MathewsNigel MathewsDavid MillerRick MinterSteve PercivalJill PerryJake PiperDavid PriceKarl RobertsMary RobinsonRobin SadlerChris ShearsGeoffrey SinclairGreg SmithMark SouthgateLiz SpencerJeffrey StevensonMarcus TrinnickSimon TribeSacha Workman

Countryside Council for WalesDepartment of the Environment Transport andthe RegionsLandscape Design AssociatesRochdale Metropolitan Borough CouncilFriends of the EarthCumbria County CouncilBurnley Borough CouncilExmoor National ParkPowerGen Renewables LimitedEnvironmentally Sustainable SystemsGreat Yarmouth Borough CouncilBritish Wind Energy Association (BWEA)Landscape Design AssociatesAspinwall and CompanyNational Wind Power LimitedScottish Natural HeritageLawrence Environmental ConsultantsBWEA (Scotland)Historic ScotlandWorldwide Fund for Nature (UK Office)Council for the Protection of Rural EnglandHarrogate Borough CouncilCornwall County CouncilMacaulay Land Use Research InstituteCountryside AgencyUniversity of SunderlandFriends of the Earth West Cumbria and NorthLakesOxford Brookes UniversityWildfowl and Wetlands TrustCarrick District CouncilRamblers Association (Wales)New PerspectivesRenewable Energy SystemsConsultant to the Council for theProtection of Rural WalesEnglish NatureRoyal Society for the Protection of BirdsNew PerspectivesJeffrey Stevenson AssociatesBond PearceWest Coast Energy Limited

B9 Energy (O&M) Limited

Further details about the preparation of this guidance, theconsensus-building process and the CEWT project outputs are givenin Annexe 3.

This document has been prepared and checked in accordance with BSEN ISO 9001 : 1994

Landscape Design Associates, December 17, 1999.

CONTENTS

CONTENTS

PREAMBLE - The purpose of the guidance

1.0 INTRODUCTION

1.1 The Principles of Cumulative Assessment

1.2 Wind Energy Development in United Kingdom

1.3 Cumulative Assessment of Wind Energy Development

1.4 Best Practice Conclusions

2.0 IDENTIFYING AND ASSESSING THE CUMULATIVE EFFECTS OF WINDENERGY DEVELOPMENT

2.1 Introduction

2.2 Global Environmental Sustainability

2.3 Local Environmental Quality

2.4 Socio-Economic Activity

3.0 SUPPLEMENTARY GUIDANCE FOR ASSESSING THE PRINCIPALCUMULATIVE EFFECTS

3.1 The Assessment of Cumulative Landscape and Visual Effects

3.2 The Assessment of Cumulative Effects on Birds

ANNEXES

1. Glossary

2. References and additional reading

3. The consensus building process behind the preparation ofthis guidance

PREAMBLE

Global concerns over the sustainable use of the earth's resourcesand climate change have resulted in the rapid technologicaldevelopment of renewable forms of electricity generation. UKGovernment policy is to stimulate the exploitation of renewableenergy sources wherever they have prospects of being economicallyattractive and environmentally acceptable (PPG 22, 1993, para.8). The energy review (DTI, 1999) confirmed the Government'scommitment to renewable technologies. At the forefront of thesetechnologies is power generation from wind energy. In the UnitedKingdom, the Government has a target of generating 10% of thecountry's electricity requirement from renewables by 2010. It isanticipated that the contribution to this target from wind energymay see installed capacity increase from the current level ofapproximately 350 MW to 3000 MW. As the installed capacity ofon-shore wind energy development grows, it has, therefore, becomeincreasingly important that the effects of extended and multipledevelopments are fully understood.

The purpose of the guidance

What does the guidance offer and who can it be used by?

This guidance provides practical information and advice on how tocarry out an assessment of the cumulative effects of on-shorewind energy development. It is aimed at developers, planners andall other stakeholders with an interest in the development ofwind energy in the United Kingdom. The purpose of the assessmentof cumulative effects is to ensure that in assessing the effectsof individual proposals, their contribution to wider changeswithin a geographical area, in combination with other similardevelopments, is understood.

Wind energy developments of either two or more turbines with aheight threshold of 15 metres or more, fall under schedule 2 ofthe Environmental Assessment Regulations (DETR, 1999a). Inpractice smaller wind energy developments may also trigger an EAwhich will include a consideration of potential cumulativeeffects. In situations where a full EA is not required, a LocalPlanning Authority may still require an assessment of potentialcumulative effects to accompany a planning application.

The assessment of cumulative effects may be undertaken either inthe context of a site specific Environmental Assessment (EA) oras part of a Strategic Environmental Assessment (SEA). These arereferred to as Cumulative Assessment (CA) and StrategicCumulative Assessment (SCA) respectively. In both instances,understanding effects will be based on similar principles. Theguidance outlines the additional steps that need to be taken whenan assessment of cumulative effects, over and above site specificissues, is required. It supports existing guidance onestablished approaches to environmental assessment, of which itassumes the reader has a good basis of understanding.

There has been growing awareness of the potential for cumulativeeffects arising from the development of wind energy over recentyears. With the extension of existing wind energy developments,

and proposals for new development in proximity to existing sites,their combined effect, over and above the effects of the proposednew development, has received considerable attention. Thesecombined effects are usually referred to as 'Cumulative Impact'in Environmental Statements, Inspector's Reports and Local Plans.In adopting the term 'Cumulative Effects', this guidance aims toavoid the assumption of a detrimental effect implied by the useof the word impact. The cumulative effects of wind energydevelopment can be either positive or negative.

The scope of the guidance was agreed in partnership withstakeholder organisations including wind energy developers,planning authorities, statutory bodies and interest groups. Therecommended approach to CA has been developed with theparticipation of these stakeholders with the aim of establishinga widely accepted and common approach. This consensus buildingapproach is outlined in Annexe 3. Inevitably, given the widedivergence of opinion between stakeholders with opposing views,full consensus was not achieved.

The guidance covers the significant environmental, social oreconomic effects that can be experienced in an area which issubject to wind energy developments. The guidance is applicableto all of the areas of the U.K. which are subject to wind energydevelopment, including England, Scotland, Wales and NorthernIreland. The guidance draws upon related publications which donot necessarily apply to all parts of the UK. This guidance isthe product of contributions by stakeholder organisation and inthe case of Northern Ireland, these have been extremely limited.The scope of the guidance is limited to on-shore development butit is acknowledged that off-shore development can have a combinedeffect with on-shore.

Interest in the cumulative effect of wind energy development hasarisen primarily because of their visibility and effects on thelandscape. As a result the term 'Cumulative Impact' has in someinstances been used synonymously to refer to landscape and visualeffects. Although this guidance recognises that landscape andvisual effects are often the principal concern of practitioners,it deals with all of the potential cumulative effects of windenergy development.

The guidance identifies practical techniques and procedures whichcan be used to understand potential cumulative effects. Therecommended approach to CA draws upon existing tried and testedmethods which have been used to assess the effects of individualwind energy developments - identifying how these can be adaptedfor use within the cumulative scenario. In some instances it isnot possible to provide a simple solution to understanding,quantifying or measuring a cumulative effect, and the guidance isable only to offer the practitioner broad recommendations. Anumber of issues are identified where further research ormethodological development may be required in future.

The aim of the guidance is to help to ensure that decision makersare provided with the best possible information on the cumulativeeffects of a proposed development to come to an informed andreasoned decision. It:

• Introduces the principles of CA• Explains why, when and by whom, CA of wind energy

developments needs to be carried out• Provides checklists of the potential effects which may needto be considered• Explains the steps that should be taken to carry out a CA• Identifies the methods which can be applied to gain the best

possible information for decision makers• Makes recommendations on presentation of information• Provides a discussion on some of the key questions and

problems which may be encountered - including a discussionon alternative views where no clear consensus amongst therelevant professionals exists.

HOW TO USE THIS GUIDE

The guidance is divided into three sections.

Section 1 sets the scene regarding CA and wind energy developmentin the U.K. It concludes with a set of pointers to best practiceindicating why, when and by whom cumulative assessment of windenergy developments should be carried out.

Section 2 provides a structure by which CA can consider the fullrange of social, economic and environmental resources which maycumulatively be affected by wind energy development. It helpsthe assessor to identify, consider and categorise all of thepotential effects. Out of this initial assessment, the principalcumulative effects will be highlighted and the assessor maychoose to refer to the more detailed guidance provided in section3.

Section 3 provides detailed assistance on the methods which canbe employed to assess the principal cumulative effects. Itincludes sections on the landscape and on birds. The approachesit recommends are not intended to be prescriptive but may beconsidered as best practice.

INTRODUCTION

1.0 INTRODUCTION

1.1 THE PRINCIPLES OF CUMULATIVE ASSESSMENT (CA)

This section of the guidance introduces the reader to someimportant generic principles which underpin CA. It outlinesthe need to identify the social, economic and environmentalresources which are being affected by change and to setpractical limits to their assessment - especially inrelation to the geographical area and period of change whichis to be considered. It recommends that a pragmaticapproach must be adopted to the potential complexity of CAto ensure that decision makers are provided with informationwhich is meaningful and significant, rather thanunnecessarily comprehensive.

1.1.1 Focus on The Resource

What do cumulative effects affect, and what should bethe focus of CA?

CA should always focus on the social, environmental oreconomic resource which is being affected by change.Each resource must then be assessed on its own termsand the scope of the assessment may differ dependingon the nature of the resource. The assessment shouldbe relevant to policy and meet statutory requirements.

1.1.2 Spatial and Temporal Limits to 'The Resource'

How does the study of cumulative effects differ fromthe study of the direct effects of an individualproposal?

Cumulative effects have two key characteristics:

• They occur over a geographical area – theassessment must identify the area over whichdevelopments may have a combined effect. Theextent of the affected area (or areas) willdiffer depending on the resource underconsideration and on specific localcircumstances. Some of the resource areas mayextend a considerable distance away from theproposal which may have triggered the need for acumulative assessment. Other resource areas maybe fragmented. Limits to the different geographicareas over which different resources arecumulatively affected must be individually set.

• They occur over time – the assessment shouldideally set the current proposal(s) in thecontext of past development, other currentproposals, and, in certain cases, what isreasonably foreseeable in the future. Theinclusion in the assessment of developments whichare 'reasonably foreseeable' is further discussedin section 1.3.4. An understanding of how

INTRODUCTION

baseline conditions have already been changed mayalso be required. Limits to the period of changemust be set and may differ for each resource.

1.1.3 Complexity

How should potential complexity and a lack of detailedand comprehensive information be handled in CA?

The assessment of cumulative effects can often proveto be extremely complex, not least because informationfor the entire area and period of change, especiallyforeseeable future changes, may be unavailable oruncertain. Absence of the comprehensive informationwhich would usually be available in a site specific EAdoes not preclude CA. Inadequacies in availableinformation should be identified, and any assumptionsclearly stated, so that decisions are taken based onthe ‘best possible’ information available to thedecision maker at the time.

1.1.4 Other land uses

Can wind energy developments have a cumulative effectin combination with other actions or land use changeswhich are affecting a resource?

CA is concerned with identifying situations where anumber of individual effects combine to cause asignificant effect on a particular resource.Cumulative effects can therefore occur as acombination of quite different actions or land usechanges within a defined area and over a definedperiod of time. The focus of this guidance is,however, wind energy development (and associated siteinfrastructure). Generally, therefore, the guidancesets out to understand the combined effects of windenergy development only.

1.2 WIND ENERGY DEVELOPMENT IN THE UNITED KINGDOM

This section of the guidance outlines the importance ofGovernment policy and describes the manner in which windenergy has been developed in the United Kingdom. Itexplains that the cumulative effects of wind energydevelopment are likely to become relevant to increasingareas of the country.

1.2.1 National Policy

Why is wind energy development taking place?

The Government has a commitment to 'a new and strongdrive to develop renewable sources of energy' (DTI,1999). It intends to work towards its aim ofachieving 10% of the UK's electricity supply from

INTRODUCTION

renewables as part of its climate change strategy toreduce UK carbon emissions. Although the Governmenthopes that the 10% target will be achieved by around2010, the policy is part of a broader drive tomaintain momentum over the longer term and to limitgreenhouse gas emissions to a sustainable level.Momentum is encouraged by support mechanisms acrossthe full range of renewable technologies. It isexpected that the current Government policy is likelyto be translated into regional targets in the nearfuture. These will probably be determined by theRegional Development Agencies in England; by theNational Assembly in Wales; and by the ScottishExecutive in Scotland, as part of their Strategies onSustainability, and cascade via Regional PlanningGuidance into Structure and Local Plans.

Generation of electricity through renewables currentlyaccounts for approximately 2% of electricityproduction - approximately 15% of this, is produced byon-shore wind representing over 350 MW of installedcapacity. It is anticipated that approximately 3000MW of installed capacity, generated by on-shore wind,will be required by 2010 to achieve the Government'spresent 10% target.

1.2.2The distribution of existing wind energy developmentsin the United Kingdom

Why have cumulative effects been experienced inparticular geographic areas?

A number of factors have influenced the geographicdistribution of proposals for wind energy developmentsand have caused groupings of developments in certainareas:

• The distribution of the viable wind resource

• Technical and economic constraints to theviability of exploiting different wind speeds

• Electricity grid access constraints

• Avoidance of proximity to habitation

• Policy or technical constraints (Ministry ofDefence, Electromagnetic interference, local andnational wildlife and landscape designations).

• The formulation of Government policy and itssupport mechanisms (e.g. Non Fossil FuelsObligation - NFFO).

These constraints to wind energy development(individually or in combination) effectively result insizeable "no-go" areas. The inverse of this effect isthat proposals for development tend to be clustered in

INTRODUCTION

favourable areas. In response to Government policyand developmental pressures, some local authoritieshave begun to identify Areas of Search for windenergy. In the future such Areas of Search may bemore commonly incorporated in Structure and Local Planprocesses.

It is possible, therefore, to identify areas whereconcern over the potential for cumulative effect ismost likely to arise. Areas with a viable windresource are also likely to widen in future as thecosts of the technology continue to fall.

1.2.3 The distribution of future wind energy proposals

Where are the cumulative effects of wind energydevelopment likely to be experienced in future?

The distribution of proposals for wind energydevelopment in the future is likely to change and tobe influenced by the following:

• Continuing and increased utilisation of high windspeed resource areas - principally in upland,western and coastal locations

• Improvements in the technology, including thedevelopment of larger turbines which will open upthe viability of areas with lower wind speeds -including lowland and eastern areas

• Exploitation of the off-shore resource (suchdevelopment does not generally fall within thescope of this guidance but it is recognised thatoff-shore developments may have a cumulativeeffect with those on-shore)

• The likely adoption within Government policy ofregional targets for renewable energy generation.This is likely to lead to a far widergeographical spread of proposed developments

• Development of a Green Electricity market and anincrease in the number of local business orcommunity initiated projects

The potential cumulative effects of wind energydevelopment may, therefore, become relevant to areasnot currently subject to pressures for suchdevelopment.

1.2.4 Categories of wind energy development in the UnitedKingdom

What kinds of wind energy development can contributeto cumulative effects?

INTRODUCTION

Wind energy developments can range in scale fromsingle, often domestic turbines (which usually do notfeed into the electricity grid) to large commercialwind farms. Individual domestic scale developmentsmay be judged to be insignificant to some resourcesand might be excluded from the assessment. There is norecognised categorisation but the following can beidentified.

• Individual grid connected wind turbines (perhapsfor on-site consumption)

• Single larger turbines

• Wind clusters – a small group (the likely scalefor community schemes)

• Wind farms – a larger group

The relationship between these different categories interms of their cumulative effect differs depending onthe specific effect in question. Unless otherwisestated the use in this guidance of the term 'windenergy development' refers to all categories andscales of development.

1.2.5 Turbine size

What is the relationship between turbine size, numberand cumulative effect?

A number of variables affect the generating capacityof a wind energy development and make importantdifferences to the potential cumulative effect thatmay be experienced in different areas.

• Taller wind turbines with larger rotor diameterscan be used to exploit the resource in lower windspeed areas

• An increase in the rotor diameter has adisproportional effect in increasing electricitygeneration. A single large turbine can generatethe electricity of several smaller turbines

• Larger turbines need to be more widely spaced androtate more slowly.

Turbine height, rotor diameter and rotation speed areall important considerations in CA. When an existingdevelopment is extended (or an additional developmentintroduced nearby) variations in the appearance, scaleand speed of movement of individual turbines mayresult in additional issues or effects.

Turbine heights (to blade tip) presently vary from a6.5m tower with a blade diameter of 3.4m (domesticscale) to a 67m tower and 62m blade diameter (eg.

INTRODUCTION

Swaffham - currently the tallest in the U.K.). Atpresent turbines within clusters and wind farms aretypically between 45 and 60m to blade tip. Larger,more powerful turbines of up to 100m to blade tip makeup the bulk of schemes which are currently beingbrought forward. The long term optimum size,considering all of the issues including perhapscumulative effects, is yet to be established.However, it is unlikely that current increases in sizewill continue.

The topographical character of an area, wind speedsand other technical considerations may thereforeresult in different preferred patterns of developmentregarding turbine size, grouping numbers and thedistribution/proximity of separate developments.

1.3 CUMULATIVE ASSESSMENT OF WIND ENERGY DEVELOPMENT

This section of the guidance brings together the precedingtwo sections which introduce the principles of CA and thenature of wind energy development in the U.K. to set outwhy, when and by whom the cumulative assessment of windenergy development should be carried out.

INTRODUCTION

1.3.1 The context for the assessment of cumulative effects

When will cumulative effects be assessed and by whom?

The cumulative effects of wind energy development maybe assessed in the context of two distinct processes.

• As part of a site specific EnvironmentalAssessment (EA) within the development controlprocess (as set out in the EnvironmentalAssessment Regulations, DETR, 1999). From thestarting point of a specific developmentproposal, its combined effects with otherexisting and planned developments may beassessed. This is most likely to be carried outby the prospective developer and reviewed by therelevant planning authority. This kind ofassessment is henceforth referred to as CA(Cumulative Assessment). The new proposal whichhas triggered the CA is referred to as the‘present proposal’.

• As part of a Strategic Environmental Assessment(SEA). From the starting point of either aresource or geographical area, the cumulativeeffects of all potential developments can beassessed. It is likely that this strategicapproach will be tackled by a regional and/orlocal planning authority or by bodies (statutoryor otherwise) with a remit to protect theinterests of a particular resource. This kind ofassessment is henceforth referred to as SCA(Strategic Cumulative Assessment).

The principles which underpin CA and SCA are largelythe same. Although this guidance has beenspecifically structured for the purposes of CA withinthe context of development control, its content isequally applicable to those wishing to complete a SCA.

1.3.2 The relationship between site specific and cumulativeassessment

Should cumulative assessment be carried outconcurrently with, or subsequent to, the assessment ofthe site specific effects of the present proposal?

Cumulative effects are an additional way in which aspecific environmental, social or economic resourcemay be affected by a new wind energy development. CAis a refinement of, and in addition to, the assessmentof the direct effects of the individual proposal whichwould typically be covered by an EA. As such, sitespecific and cumulative effects are usually beststudied concurrently, their magnitude combined andsignificance jointly assessed. CA will alsoconcurrently feed into the iterative design process to

INTRODUCTION

ensure that the proposed development is refined toincrease its acceptability in cumulative terms. Thefinal assessment should identify the significance ofthe total effect on the resource of the proposeddevelopment and this will include its contribution tovarious cumulative effects.

INTRODUCTION

1.3.3 Cumulative effects

In what circumstances might wind energy developmenthave a cumulative effect?

The cumulative effects of wind energy development arethe combined effects of:

• an existing wind energy development and anextension to that development

• more than one wind energy development proposed atthe same time within an area

• a new wind energy development and one or moreexisting developments

• any combination of the above

1.3.4Setting limits to the assessment of the cumulativeeffects of a proposed wind energy development

Which other existing and proposed wind energydevelopments should be considered by the cumulativeassessment?

The limits which need to be placed upon the assessmentof a cumulative effect, to which an individualproposal may contribute, have been identified asspatial (the area over which the combined effectoccurs) and temporal (the period over which changeoccurs). These limits to the scope of the cumulativeassessment must be separately defined for each of theaffected resources in turn and will require pragmaticjudgements to ensure that assessment is practicableand its results meaningful. The existing and proposedwind energy developments which are considered in thecontext of each individual resource will, therefore,be different. A sequential approach to identifyinglimits, which is applicable to all resources, is setout in box 1.1.

INTRODUCTION

Box 1.1

Setting limits to the assessment; the existing andproposed wind energy developments which should beincluded.

The limits to assessment must be identifiedseparately for each resource. How each of thefollowing stages is approached will differ for eachresource. Where appropriate, recommended approachesare highlighted in the subsequent guidance.

A. Identify the direct or site specific effects ofthe present proposal.

B. Identify the social, economic or environmentalresources which will be affected by the presentproposal.

C. Define a geographical limit for each resource.This will vary widely depending on the nature ofthe resource (eg. a designated landscape, a birdpopulation or a local economic area). In somecases the resource area may be fragmented.Resource areas will rarely coincide withadministrative boundaries.

D. Identify the existing wind energy developmentswhich are already having an effect on theresource within any part of its overall area.

E. Identify all other reasonably foreseeable windenergy developments which may affect theresource (see below).

F. Complete an initial assessment to identify whereand when the most significant cumulative effectsare likely to occur and which will requiredetailed investigation. It may be possible atthis stage to acknowledge potential cumulativeeffects on some resources but to determine thatfurther investigation is either unnecessary, asits significance will clearly be limited, orimpracticable to assess. It may also be judgedto be appropriate to restrict the geographicalscope of the detailed assessment to only partsof some resource areas, although such decisionsmust be justified.

It will be necessary to identify other 'reasonablyforeseeable' wind energy developments which may affectresources within their defined geographic limits inthe future. It will be useful to place the assessment

INTRODUCTION

within its broad context; to provide a brief review ofGovernment policy on renewable energy and its specificregional implications in the area being studied. Thiswill enable general statements to be made about thelikelihood of further wind energy development over themedium and long terms.

Future developments are likely to fall into one of thefollowing categories:

• Under construction• Approved planning applications• Proposals in the ‘planning process’• NFFO (or similar) contract schemes• Others

Given that the planning system is aimed at providingcertainty, CA should include only built and permitteddevelopments and those already in the planning processunder determination for which design information is inthe public domain. More speculative proposals,including those with NFFO or similar support, might beincluded by agreement with the planning authority butthis will clearly render the assessment less certain.It may be the case that less certain potential futuredevelopments might be usefully considered in thecontext of some resources, but not others. A SCAcould incorporate all potential schemes, but shouldnot be used as a basis for judging the acceptabilityof an individual scheme. An SCA in this respect wouldbe a ‘higher level’ document than a CA and is morelikely to be relevant to the implementation ofregional targets for renewable energy.

During this process the assessor will have located allof the potential developments, existing, planned andspeculative, which might potentially contribute to acumulative effect. Inherent in this process, however,should be an initial Assessment of the likelysignificance of various effects which will help theassessment to focus on those issues which meritdetailed investigation.

Where appropriate, subsequent guidance set out insections 2 and 3 provides further advice on whichexisting and proposed wind energy developments shouldbe included in the cumulative assessment of specificresources.

1.4 BEST PRACTICE CONCLUSIONS

From the preceding sections the following pointers towardsbest practice can be identified and are set out in Box 1.2.

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Box 1.2

Generic Best Practice in Cumulative Assessment

• Scope:Consult on the scope of the assessment and agree thecategories of future developments which will beincluded in the assessment.

• CA/SCA:Be clear about whether a strategic or site specificcumulative assessment is called for and that anappropriate body is being asked to take on the task.

• Policy:Place the assessment of effects in the context ofGovernment policy, regional targets/quotas and abroad appreciation of the local distribution ofviable and potentially exploitable wind resource.

• Resource:Focus assessment on the principal social, economicand environmental resources which may be subject tocumulative effects.

• Own Terms:Assess the effects on each resource on its own terms,and vary the scope and geographical extent of theassessment accordingly.

• Inclusion:Assess the cumulative effects of all existing andreasonably foreseeable wind energy developments. Theinclusion of less certain future development maydiffer for each resource and may depend on an initialjudgement on the likelihood of a significant effect.

• Limits:Place pragmatic limitations on the assessment toavoid unnecessary complexity and to efficientlyidentify the most significant potential effects.

• Other Changes:Limit the assessment of each individual resource tothe specific effects of wind energy development uponit.

• EA/CA:Complete a CA as a concurrent and integrated exercisewithin a site specific EA.

• Monitoring:Post construction monitoring of important effectsshould be carried out.

2.0 IDENTIFYING AND ASSESSING THE CUMULATIVE EFFECTS OF WIND ENERGY DEVELOPMENTS

2.1 INTRODUCTION

2.1.1 Cumulative Effects, Resources and Categories

This section of the guidance provides the reader with a listof the effects which may result from wind energy developmentand which may need to be considered in the context ofcumulative development. This list is representative of abroad consensus amongst relevant professionals. It isintended to be comprehensive but not exclusive. Othereffects may warrant inclusion in particular circumstances orin future development scenarios.

The guidance suggests a way in which the effects can beusefully categorised to help to identify the resources whichare ultimately affected and to provide a structure wherebyboth global and local considerations can be considered.Precise definition and categorisation of effects which areinterrelated in complex ways is difficult. There are clearlinks, for example, between effects on the landscape,tourism and employment. There is, nevertheless, broadagreement that the categorisation of the effects is a usefulapproach to their analysis.

Box 2.1

A definition :

The cumulative effects of wind turbines are the combinedeffects on principal social, economic or environmentalresources of extended or additional wind energydevelopments within specific resource areas.

They include social and economic as well as environmentaleffects.

They can be adverse or beneficial.

CA is concerned with identifying situations where a numberof individual effects combine to cause a significant effecton a particular resource.

Box 2.2 is an assessment matrix which provides, at a glance,a full summary of the potential cumulative effects of windenergy developments and how their assessment should beapproached. The potential effects are listed andcategorised in the left hand columns. Sections 2.1.2 to

2.1.4 provide further explanation of the matrix. Section2.2 considers the assessment of each of the effects in turn.

Box 2.2 : The Assessment Matrix

Categories Resources

Qualitati

Quantitat

i Additive

Threshold

Effects Relevance to CumulativeAssessment

CumulatiAssessmeNecessar

Energy x x Energy production . Place in context of local orregional generation by renewables. See section 2.2.1

YES

GLOBAL ENVIRONMENTALSUSTAINABILITY

x x ution and CO2 emission. Place in context of local orregional generation by renewables. See section 2.2.2

YES

Biodiversity

x x x Flora . Generally not a cumulative issue. May occur for certain vegetation communities. May occur in future. See section 2.2.3

Possibly

Fauna . Only recognised effect is thaton birds. See section 2.2.4 and section3.1

YES

TheLandscape

x x Landscape character(the fabric,character andquality of thelandscape includinghistorical andcultural aspects)

. Most important potential effect

. Assessment methods alreadyinvestigated. See section 2.3.1 YES

Visual amenity(changes inavailable views)

. Important potential effect

. Must be handled separately toLandscape Character. See section 2.3.2

YES

LOCAL ENVIRONMENTALQUALITY

x x Noise . Unlikely that there will be acumulative effect. Refer to existing guidelines onnoise. See section 2.3.3

NO

Accessibility . Accessibility may increase ordecrease. See section 2.3.4

NO

Recreationalopportunity

. Opportunity may increase ordecrease. See section 2.3.5

YES

Shadow, flicker,movement ofturbines

. Generally site specific effects

. Adequately handled in sitespecific appraisal. See section 2.3.6

NO

The Economy x x The Local Economy . Can be considered locally orregionally. Direct or indirect jobs created. 'Critical mass' must be reachedfor local specialist businesses to beviable. See section 2.4.1

YES

Tourism . May be adverse or beneficial. Different groups/visitor typesmay be attracted or detracted. Effect unlikely to becontinuously additive as development increases. Complex issue which requiresfurther research. See section 2.4.2

YES

SOCIO-ECONOMIC ACTIVITY Sustainablecommunities

. Small levels of local employmentmay tip the balance for small communities. See section 2.4.3

YE

Electromagneticinterference

. Generally site specific

. No additional cumulative effectidentified. See section 2.4.4

NO

People x x Education andpublic awareness

. Possible improved awareness of issues relating to sustainabilityand global warming. Greater awareness of energy uselocally. Greater awareness of GovernmentPolicy. Effects unlikely to besignificant beyond the initial low levels of development. See section 2.4.5

YE

2.1.2 Resources

Cumulative assessment should always focus on the resourcewhich is ultimately affected. In identifying the potentialcumulative effects of wind energy development it is usefulto identify the ultimate social, economic or environmentalresource which is subject to the effect and to furthercategorise these resources in relation to the scale at whichthey are affected - whether the levels of concern are globalor local. Although the categorisation of effects intoglobal and local is useful for the purposes of presentation,it must be noted that effects are often experienced at allscales. Effects on biodiversity (flora and fauna), forexample, clearly have a local dimension. It is likely thatit will be possible for local levels of concern to beaddressed in full by the development control process butthat global issues can only be considered briefly to providean appropriate context. The approach to identifyingresources and their limits is set out in section 1.3.4.

2.1.3 Objectivity

It is always good practice to clearly identify which partsof the assessment are entirely objective and which contain adegree of subjective or professional judgement. Incumulative assessment this is likely to relate in particularto whether the effects upon the resource are quantitative orqualitative. It should be recognised, however, that evenwhere an effect is quantifiable, a judgement about itssignificance will be required.

2.1.4 The Nature of Cumulative Effects

The nature of the combined effects of extended or additionalwind energy developments fall into two distinct categories:

Additive: Where the magnitude of the effect is entirelyproportional to the amount of development, ie.two wind farms of the same size simply have twicethe effect as one.

Threshold: Where the relationship is non-linear and far morecomplex. An additional development may alone beinsignificant but cumulatively 'tip the balance',or the presence of an existing wind energydevelopment may magnify or reduce the effects ofa second.

2.2 GLOBAL ENVIRONMENTAL SUSTAINABILITY

2.2.1 Energy Production

Individual wind turbines can now produce up to 2 MW ofelectricity. On average, this is enough power for around1250 homes. However, it is only cumulatively that windenergy developments can be understood to be increasinglysignificant contributors to regional and national energyneeds. An individual wind farm's contribution to meetinglocal or regional need will be more tangible than nationalneeds. In the cumulative assessment, energy productionshould be considered by reference to its percentagecontribution to local or regional need. It will generallybe beneficial.

2.2.2 Pollution and CO2 Emissions

The electricity which is cumulatively generated by windenergy developments reduces the proportion of electricityconsumption which is met by burning fossil fuels. Areduction in CO

2 emissions and other associated pollutants

will be a positive cumulative effect at the national/globalscale. The Kyoto target for CO

2 reduction is legally

binding. Similar legally binding domestic targets at thenational, regional or local scale have not been established.The developer would normally provide information on COreductions which may be assessed in the context of local,regional or national targets, where these exist. However,regional targets may be more tangible than international ornational targets, when considering the significance of aproposed development in the cumulative scenario.

2.2.3 Flora

The cumulative effects of wind energy development upon floraare likely to be beneficial, through the aggregate effect ofindividual developments in reducing the adverse effects ofclimate change upon plants, especially in temperate uplandareas. These beneficial effects are very difficult toquantify at a local, regional or even national scale buttheir contribution to global environmental sustainabilitysuggests that attempts at quantification should beundertaken in a generic manner, if possible. This may bebeyond the capability of individual applicants.

Wind energy developments do lead to some loss of sitevegetation (mainly due to access roads) but this isrelatively limited due to the nature of development. Thereis, at present, little concern that individual site lossesmay cumulatively become significant. There are, however,certain vegetational communities that coincide with thepresent distribution of developments, and some of these maybe sensitive to hydrological disturbance. Some of thesecommunities, such as blanket bog and wet heath, areprotected by the Habitats Directive and therefore warrant

special attention. Good construction practice should aim toavoid such hydrological effects extending beyond thevicinity of turbine bases and access routes. Such effectsshould certainly be contained within the site boundary andwould therefore be unlikely to cause cumulative effects.Other similar correlations between wind resource areas andhydrologically sensitive vegetation types may occur infuture but there are not, at present, any predictedcumulative effects on vegetation communities.

2.2.4 Fauna

As for flora, the cumulative effects of wind energydevelopment are likely to be beneficial through slowing ofclimate change. Most cumulative effects of wind turbinesupon fauna which have been identified in the consultationprocess relate to birds. Such ornithological or avianconsiderations reflect the depth of existing knowledge onthese areas of biodiversity and the resources of specialistgroups such as the RSPB. It is possible that cumulativeeffects upon invertebrates for example, might arise in somesituations but would probably remain undetected. Thedevelopment of Local Biodiversity Action Plans should helpraise awareness of invertebrates and may generate moreinformation against which to assess the potential effects ofdevelopments.

General guidance on how to assess the cumulative effects ofwind energy development on birds is included in section 3.2of this guidance.

2.3 LOCAL ENVIRONMENTAL QUALITY

2.3.1 Landscape

Effects on the landscape are widely considered to be animportant potential cumulative effect of wind energydevelopment and have already been the subject ofinvestigation and methodological development. It isimportant that effects on the landscape (its fabric,character and quality), and effects on available views ofthe landscape, are handled separately. Visual amenity isdiscussed below in section 2.3.2.

Detailed guidance on the assessment of the cumulativeeffects of wind energy development on landscape is set outin section 3.1 of this guidance. It is generally acceptedthat wind energy developments will not often cumulativelylead to significant loss of, or damage to, the fabric of thelandscape. Rather it is the effect on the overall qualityand character of the landscape, and the values with whichthe landscape is associated, that will need to be assessed.It is generally accepted that a cumulative effect on thelandscape is not dependent on the simultaneous visibility ofmore than one wind energy development.

2.3.2 Visual Amenity

Cumulative effects on visual amenity concern the effect thatwind energy development can have on specific views that areenjoyed by people at fixed locations or as they pass throughthe landscape. In these situations it is important thatwind energy developments are seen to fit into the aestheticof their landscape context and that their pattern ofdistribution within the landscape is appropriate.Cumulative assessment may also consider the frequency atwhich wind energy developments are seen from linear routespassing through the landscape. This may be approached as aneffect on perceived landscape character as well as a seriesof individual visual effects at the various points along theroute. Detailed guidance on the assessment of thecumulative effects on visual amenity is also provided withinsection 3.1.

2.3.3 Noise

Noise has been an important issue for the wind energyindustry and has been investigated in depth. Concerns overnoise relate not only to its level (in decibels) but also tothe type or character of the sounds produced. Advances inturbine technology continue to reduce noise levels and thesituation may improve further in future. Detailed guidanceon the assessment of noise exists (ETSU, 1996). Althoughthere are reports of turbines being heard over considerabledistances, techniques for measurement are well defined. Forthere to be an issue of cumulative noise, developments wouldtherefore need to be in close proximity to one another. Itis widely felt, however, that noise may be handledadequately in site specific assessments and that anyadditional cumulative effect can be successfully addressedwithin the existing framework.

2.3.4 Accessibility

Wind energy developments and their associated access roadssometimes lead to changes in the accessibility to thecountryside. This may be either increased or reduced but inpractice developments are most likely to open up access toareas, often hilltops, that had been previously largelyinaccessible. Changes in access may relate to pedestrians,horseriders or vehicles. Effects may result from changes inbehaviour by both recreational visitors and farmers.Changes in accessibility can therefore lead to changes inland use which may cumulatively have a significant effect.To date, however, changes in accessibility have not arisenas a significant cumulative effect which would meritdetailed investigation.

2.3.5 Recreational Opportunity

Changes in recreational opportunity relate almost entirelyto changes in the accessibility of the countryside (by foot,horse, bike or car) and any visual effect (see section 3.1).The comments in paragraph 2.3.4 therefore also apply here.

2.3.6 Shadow/flicker and Movement

Although clearly influential upon the visual effects of windenergy development the movement inherent to turbines, andalso its relationship with sunlight, can lead to changes inthe general amenity of areas and dwellings. These are mostusually micro-scale issues which are specific to a singlesite and a single receptor. There is, therefore, generallyno cumulative effect and falls within the scope of generallandscape and visual effects.

2.4 SOCIO-ECONOMIC ACTIVITY

2.4.1 The Local Economy

The international wind energy industry is currently growingat a rate of 30% and a wind farm represents significantopportunities for employment and investment. At a nationallevel, therefore, there will be a cumulative economicbenefit. The potential cumulative benefit of additionalschemes at a local and regional level should be explored.

A wind farm generally represents new investment in a ruralarea. Additional schemes in a region may benefit from localexpertise gained at existing facilities and cumulatively anumber of schemes may lead to a stronger regional windindustry base.

There is, therefore, the potential for significantcumulative economic effects of further wind energy schemeswithin a defined region at all stages in the developmentprocess (development, construction and operation). Thesemay be direct or indirect effects of the development.Direct effects may include those upon landowners, localconsultants, service companies (eg. hotels, shops,security), local contractors (fencing, labour), thecommunity (eg. community support programs, improved roads,employment) manufacturers (towers, components). Indirecteffects are likely to mainly be linked to an increase in thelocal economic base.

Potential positive effects must be balanced with anassessment of potential negative effects on the economicbase of an area. These may include increased traffic levelsand effects on tourism (see below). Negative effects arelikely to be considered within other aspects of theassessment such as the cumulative visual effect.

Site specific and cumulative effects should be clearlydistinguished.

2.4.2 Tourism

The potential for wind energy development to affect theattractiveness of an area for tourism has arisen as an issuein some areas. This complex relationship has been littleresearched. Early developments may act as touristattractions for some people. Conversely, others may bedeterred from visiting an area with significant development- although this remains unproved. With increasing numbersof developments in an area, a correlating increase in thenumber of tourists attracted can not be expected. Changes tothe character of the area may deter people or lead to achange in the kind of people who visit and the activities inwhich they indulge. This is clearly an effect for which itis difficult to define thresholds. Section 3.1 of thisguidance considers thresholds to changes in people'sperception of landscape character and the values with whichan area is associated. Further research is requiredregarding the economic effects of these changes on tourism.

2.4.3 Sustainable Communities

Small rural communities are vulnerable to small changes insocio-economic circumstances. The significance of a smallchange to local employment levels and levels of tourism maytip the balance, one way or the other. This is difficult toassess and also links to other effects or changes. The sizeof the local population and its socio-economic activity willaffect the manner and degree to which the local landscape ismanaged for example. The cumulative effect of more than onedevelopment must be considered on a site by site basis.

2.4.4 Electromagnetic Interference

Interference is generally well understood and reasonablypredictable. It is a significant resource constraint butissues can be tackled on a site by site basis, at the siteselection stage, and there are no additional cumulativeconsiderations.

2.4.5 Education and public awareness

The presence of wind energy developments in an area can havean effect on local people's understanding of wind energy; ofits environmental significance regarding CO

2 and other

emissions; and of the Government Policy context to itsintroduction. A number of public perception studies, alongwith focus group research carried out during the preparationof this guidance, have provided an insight into howperception changes when wind energy developments areconstructed. There is evidence that understanding,knowledge and support increases post-construction. It isunlikely, however, that the magnitude of this effect will becumulatively additive as more wind energy developments areproposed and built. For example, the educational value of anadditional wind farm is unlikely to be as high as the firstin an area. It will be dependent on the nature of windenergy development, the specific area and the type ofvisitor. Further research is required.

2.5 INTERPRETING THE WHOLE PICTURE

The cumulative effects of wind energy development on all ofthese different resources may include both beneficial anddetrimental effects of differing magnitude and significance,and effects which are experienced at widely varying scales.Their assessment will include economic and social measureswhich cannot be compared, like-for-like, with less tangibleenvironmental effects. The balancing and weighting ofdifferent cumulative effects is extremely complex. In thecontext of cumulative wind energy development, this islikely to come down to the challenge of balancing local andglobal effects.

The use and development of Sustainability Appraisals andtools such as Environmental Capital methodologies (CAG/LUC,1997) may assist in the process of understanding therelative scale and importance of different kinds of effects

in England and Scotland. (In Wales LANDMAP is the preferredapproach). The Environmental Capital approach aims to guideplanning and decision making in a way which is inclusive andcapable of determining the importance of things, whetherthey are tangible (readily measurable) or intangible(difficult to objectively quantify). The methodology asks"what matters, to whom, and why?" It places a particularemphasis on the benefits which can be achieved. Althoughits early development has focused on the environment, it ishoped that the methodology will be increasingly applied toeconomic and social issues, and their full range ofpotential benefits (Richard Wakeford, 1999).

The UK Government has published its strategy for sustainabledevelopment for the United Kingdom (DETR, 1999b). Thisstrategy seeks to define sustainable development throughfour objectives which any development or proposal must meet,namely:

• Social progress which recognises the needs ofeveryone;

• Effective protection of the environment;• Prudent use of natural resources;• Maintenance of high and stable levels of economic

growth and employment.

Closely related to these objectives are three types ofcapital, i.e. social, economic and environmental capital,whose measurement and monitoring are key parts of theGovernment's view of, and approach to, sustainabledevelopment.

Within the Government's Strategy, "electricity fromrenewable sources" is one of a series of approximately 150indicators against which progress on sustainable developmentwill be judged.

At present renewable energy technologies including wind haveno agreed sets of sustainability criteria on whichstakeholders can base their judgements in local, regional ornational circumstances. This is a subject of currentresearch commissioned by ETSU.

3.0 ASSESSING THE EFFECTS

3.1 THE ASSESSMENT OF CUMULATIVE LANDSCAPE AND VISUAL EFFECTS

3.1.1 The cumulative landscape and visual effects of windenergy development

(i) What does this section of the guidance cover?

This section of the guidance considers cumulativeeffects upon both the landscape (its fabric, characterand quality) and on visual amenity (views enjoyed bypeople). Landscape and visual effects clearly havelinks with effects on other resources. This reflectsthe difficulties associated with defining andcategorising effects which are interrelated in complexways. Landscape and Visual effects in particular linkto effects on tourism and general amenity. Effects onthe cultural and historical heritage of an area areconsidered in this section insofar as they contributeto landscape character.

Approaches to assessing landscape and visual changesare well established and set out in a number ofguidance documents (eg. Landscape Institute/Instituteof EA, 1995; Countryside Agency/SNH, 1999; CountrysideCommission 1993, CCW, 1998). The established approachadopts characterisation as its foundation, againstwhich the significance of change can be judged. Thisguidance assumes a thorough grounding in theseexisting methodologies and focuses on their adaptationor application to the specific requirements of thecumulative assessment of wind energy development.

(ii) How is the landscape cumulatively affected by windenergy development?

It is an established principle that effects on thelandscape and effects on visual amenity should beassessed separately (Landscape Institute/Institute ofEA, 1995).

Effects on the landscape include:

• Loss of or damage to the specific elements whichmake up the fabric of the landscape.

• Changes to the perceived character and quality ofthe landscape.

Effects on visual amenity include:

• Changes in the available views of the landscapeenjoyed by people.

Individual wind energy developments generally have alimited direct effect on the physical elements whichmake up the fabric of the landscape. The loss ordamage which may occur is usually adequately coveredby site specific EA and there is, at present, littleconcern that these might add up to be cumulativelysignificant. Assessment of cumulative landscape andvisual effects is, therefore, principally concernedwith changes in the appearance of the landscape, itsperceived character and the nature of specific views.

Potential cumulative effects on the landscapetherefore relate principally to:

• the degree to which wind energy developmentbecomes a significant or defining characteristicof the landscape, and especially;

• the degree to which wind energy developmentaffects the values and experiences which might beassociated with the landscape (e.g. its wildnessor sense of history).

Cumulative visual effects relate to:

• the degree to which wind energy developmentfeatures in particular views (or sequences ofviews) and the effect this has upon the viewer.

In some circumstances variations in the appearance,overall height, rotor diameter and rotation speed ofturbines, either added to, or adjacent, an existingsite may lead to additional visual effects (causingvisual confusion) in the cumulative scenario.

In all cases the contribution of wind energydevelopments to the landscape or to specific views maybe either beneficial or adverse.

(iii) When do cumulative landscape and visual effects occur?

Wind energy development may have a cumulative effectin two distinct circumstances:

• When two or more sites (or a site and itsextension) are simultaneously visible from areasof mutual visibility (whether sites themselvesare intervisible or not)

• When two or more sites (or a site and itsextension) are seen sequentially, but notsimultaneously, whilst passing through thelandscape.

For cumulative landscape and visual effects to occurit is neither necessary for different sites to besimultaneously visible, nor necessarily fordevelopments to be seen at close quarters. Effects

can therefore occur when developments are seensequentially over time or when visibility occurs overlong distances. That cumulative effects are notDependent on simultaneous visibility has importantimplications for the identification of geographicallimits to the assessment as is discussed in section3.1.2.

(iv) Over what distances can wind energy developmentscontribute to cumulative effects?

Wind energy developments can theoretically be visibleover very long distances. This distance is also likelyto increase as developing technology leads to higherturbines.

The significance of the visibility of wind energydevelopment at various distances will differ dependingon whether its landscape or visual effect is beingconsidered. Broadly speaking, the significance ofvisibility over longer distances is likely to have amore significant effect on general perceptions ofcharacter than it is on the nature of a particularview. Put another way, simply because turbines aretoo far away to 'dominate' or significantly change anidentified view, it can not be concluded thatperceptions of the general character of the landscapehave not been significantly affected one way oranother.

Another important, but limited, cumulative issue whichrelates to distance concerns the possibility of visualcoalescence. Visual coalescence will occur where twowind energy developments which have clearly separategeographic sites appear as one from certain viewpointswithin the landscape. Such an effect may be perceivedas either beneficial or adverse. Current levels ofdevelopment in the UK have not generally resulted inexamples of this effect, but this may change in thefuture, albeit in a limited number of locations.Visual coalescence will clearly depend on the distancebetween sites. But it will also depend on the extentof each individual site, the height and relativeheight of the turbines, and the distance away fromwhich they are viewed. The legibility of theirseparation may be further reduced if turbines ofdiffering heights are used - especially if thosefurther away are higher. The importance ofconsidering this potential effect lies in itspotential to contribute to perceptions of a 'windenergy landscape' (see section 3.1.6).

The question of the distance over which wind energydevelopments may contribute to cumulative landscapeand visual effects is not entirely Dependent on thedistance over which they may be visible. Wind energydevelopments may be visible from different parts of alandscape area (eg. different parts of a designated

AONB) or at points along a linear visual receptor (eg.from different lengths of a public footpath). Theperceived effect on landscape areas or linear routescan therefore theoretically occur between sites whichare a considerable distance apart (eg. either end of aNational Trail). The distance over which asignificant effect will persist will be a matter forprofessional judgement in each individual case. Itcan probably be said, however, that perceivedassociations are more likely over areas of consistentlandscape character and over shorter journey times.

(v) How should the cumulative effects of wind energydevelopment on the landscape be assessed?

This guidance sets out the four principal steps tocomplete an assessment of cumulative landscape andvisual effects. The landscape methodology is based onthe widely adopted approach to landscapecharacterisation advocated by the Countryside Agency(in England) and Scottish Natural Heritage (inScotland), Countryside Agency/SNH, 1999), and iscompatible with the LANDMAP methodology in Wales (CCW,1998). Landscape characterisation is also advocatedby PPG7 (DoE, 1997). The approach to Landscape andVisual impact assessment is based on best practice(Landscape Institute/Institute of EA, 1995). It isrecommended that CA is concurrently completed andintegrated with the equivalent steps in the sitespecific EA of the present proposal (rather thancompleted and presented as a subsequent and separateexercise). The guidance provided within the followingfour sections covers each of the steps in turn.

The four steps are summarised in box 3.1.

Box 3.1

The four steps to Assess Cumulative Effects on theLandscape

Step 1 A comprehensive review ofpotential cumulative effects onlandscape and visual receptors andan initial assessment of theirsignificance. This approach isintroduced in section 1.3.4 (seebox 1.1). This step shouldconclude with identification ofthe landscape and visual receptorswhich require detailedinvestigation, the extent of thetotal study area and a clearstatement regarding which otherexisting and proposed future windenergy developments will be

considered by the assessment.This identifies the scope of thedetailed assessment.

Step 2 A description of the baselinelandscape and visual conditions.In cumulative assessment thepresence of existing wind energydevelopments must be handledcarefully, the values associatedwith the landscape highlighted andinitial judgements made about thesensitivity of the landscape towind energy development.

Step 3 The assessment of the magnitude ofthe cumulative effects, theirinterpretation and representation.This involves the adaptation ofvarious assessment tools includingzones of visual influence (ZVI),viewpoint analysis and montagerepresentation of effects.

Step 4 The judgement of significance.This involves the application ofthresholds, capacity andprofessional judgement.

3.1.2 Step 1 - Identifying the Receptors of Cumulative Landscapeand Visual Effects – setting spatial and temporal limits

Step 1 is concerned with identifying all of the potentialcumulative effects towards which the present proposal maycontribute. It expands upon the guidance set out in section1.3.4. At this stage the scope of the assessment should bebroad, comprehensive and inclusive. It may then beappropriate for some potential effects to be simplyacknowledged, whilst others will go forward to be assessedin detail.

(i) Preliminary ZVI

As part of the site specific EA it is likely that acomputer generated zone of potential visual influencewill have been produced. This preliminary ZVI canalso be used to identify the receptors in C.A (seebelow). The area the ZVI covers, usually a circlecentred on the development, will be defined by thenature of the planned development and the height ofthe turbines proposed. It should identify all areasof potential visibility. A 20 km radius would betypical. The ZVI should relate to blade tip in thisfirst instance to provide a "worst case" baselinewhich can be progressively refined.

(ii) Receptors

With reference to the preliminary ZVI, a comprehensivelist of the landscape and visual receptors which maybe affected by the present proposal can be produced.These will include:

• Landscape areas• Routes through the landscape• Specific views

Box 3.2 provides a checklist of possible receptors.

Box 3.2

Landscape and visual receptors which may becumulatively affected by wind energy development.

Landscape Areas

• Administrative - Nation, Region, County,District, Parish/Community,Town, City

• Designatory - National Park, AONB, SLA (etc),Heritage Coast

• Character - Landscape character area (national, county, local,

historical or cultural),landscape units or types

Linear Routes

• Public Rights of Way (bridleways, footpaths) andNational Trails

• Major roads, railways, cycleways, canals andother watercourses

• Scenic drives and tourist routes

Specific Individual Views

The views enjoyed by people from:

• Publicly accessible land

• Homes, settlements

• Special viewpoints

• Specific points along linear routes such asroads and footpaths

An initial review of all areas, routes and views mustbe carried out to identify whether they may be subjectto a cumulative effect. In the case of landscapeareas and linear routes, it is necessary to identifywhether the present proposal is contributing tocumulative effects taking place well beyond its ownzone of visual influence. It is for this reason thatthe study area for a cumulative assessment will notnecessarily be a circle based on its ZVI. The studyarea should instead be understood as a composite ofall of the potentially affected receptors which havebeen identified. This will extend by different

distances in different directions depending on thedistribution and size of landscape character areas andthe relevant length of linear routes (for example itmay be necessary for the ‘study area’ to include asignificant length of a National Trail). It may beappropriate to work at a regional scale of 1:200,000.It may then be possible in some circumstances toidentify an arbitrary circle which encompasses all ofthe receptors.

(iii) Other existing and reasonably foreseeable wind energydevelopments to include in the cumulative assessment

Taking each of the individual landscape resources inturn, existing developments in the planning processwhich may have a combined effect with the presentproposal must be identified. The object of theexercise is to quickly identify where and when themost significant cumulative effects, which willrequire detailed investigation, may occur.

Some landscapes resources may be identified as beingpotentially cumulatively affected by developmentswhich are both certain and imminent. For others theremay be an expectation of greater levels ofdevelopment, but with less certainty and not withinthe short term. The response to these variablesshould be clearly and logically argued and ideallyagreed with the planning authority and others.

The final judgement over inclusion must be based onwhat is most meaningful, reasonable and practicable.The landscape and visual effects of planned ortentative proposals are extremely difficult to assessif details are not available on the precise nature ofthe proposals (turbine height, site distribution,etc.) Their inclusion with such uncertainty maytherefore contribute very little to the assessment.On the other hand a landscape resource, perhaps alandscape type fragmented throughout an area, may besubject to the effects of a large number of tentativeproposals. In this circumstance it may be moremeaningful to draw some broad preliminary conclusionsand highlight the likelihood of a future effect,rather than to entirely exclude because of theuncertainty. As has been previously emphasised, thisis best decided on a site by site, resource byresource (receptor by receptor) basis.

It should be possible to make a preliminary assessmentof the significance of potential cumulative effects atthis stage and prior to the preparation of additionalcomputer generated zones of visual influence.

Example: Motorway: another site 50 km away :preliminary assessment; little significance;issue noted in the assessment but not furtherinvestigated.

Example: AONB : other wind energy developments visiblein other parts of the designated area :preliminary assessment; a potentiallysignificant issue; refer to the JointManagement Board or local Planning Authority(eg. Sussex Downs Conservation Board) forcomment.

This process will ensure that the assessment processacknowledges all of the potential cumulativesituations to which the present proposal maycontribute.Additional studies by other bodies may also betriggered.

At the end of this process it should be possible toprovide a schedule of all of the other wind energydevelopments which are to be investigated in thesubsequent detailed assessment. It is useful for thisschedule to provide outline statistics for eachdevelopment such as the number of turbines and theirheight. It may also be possible to summarise whichindividual landscape and visual receptors maypotentially be affected by which developments. Whereit is has been judged necessary to include futureproposals in the assessment for which detailedinformation is not available, this will be highlightedby the schedule. This will present a clear agenda forthe subsequent detailed investigations of potentialeffects set out in steps 2 to 4.

3.1.3 Step 2 : Describe the Baseline and its sensitivity towind energy development

General guidance on how to tackle the description ofbaseline conditions, (the character and quality of thelandscape and views prior to development) is provided byexisting guidance. It is useful, however, to additionallyhighlight the following issues which specifically relate toCA.

(i) Existing wind energy developments

Existing wind energy development must be included inthe description of baseline conditions. Neverthelessthe effect that wind energy development is alreadyhaving on baseline characteristics of the landscapemust be well understood. This existing effect may bebeneficial or adverse. It is important to ensure thatthe cumulative assessment acknowledges the ongoingprocess of change over time.

(ii) The intrinsic values which contribute to baselinelandscape character

It has been recognised that wind energy developmentcan affect the intrinsic values or experiences which

might be associated with a landscape. In practice,this has primarily focussed on the associations whichmay be weakened by the presence of wind energydevelopment. A positive effect on intrinsic values isequally possible but is at present less wellunderstood. The detailed assessment of these factorsis important to the baseline description in cumulativelandscape assessment although they are, by theirnature, very subjective. They will form some of thekey criteria by which the sensitivity of a landscapeto wind energy development may be understood.

(iii) Quality of the baseline landscape

An understanding of the quality of character of thedifferent landscape receptors will be needed. Thequality of a landscape is defined in interim guidance(Countryside Agency/SNH, 1999) by comparing itscondition against a set of defined criteria, and notby its relative scenic value (see box 3.3). Alandscape which might not be judged scenic can,nevertheless, be a high quality example of itsparticular landscape type or character. In thecontext of cumulative assessment of wind energydevelopment it may be felt that scenic values, asdiscussed above, are of greater relevance than thequality or condition of a particular character area.It would be inappropriate to conclude in all cases,for example, that landscapes which are in a poorcondition are better able to absorb wind energydevelopments. The intrinsic aspects of thelandscape's character, whatever its current condition,is a more useful starting point from which to assesssensitivity and capacity for development.

Box 3.3

Making Judgement about Landscape (extract fromCountryside Agency/Scottish Natural Heritage, 1999)

Landscape character is what makes one landscapedifferent from another. It means the distinct andrecognisable pattern of elements that occursconsistently in a particular type of landscape.Distinctive character results from particularcombinations of geology, landform, soils, vegetation,land use, field patterns and human settlements. Itcreates the particular sense of place of differentparts of the landscape.

Landscape quality is related to character and is notthe same as scenic beauty in the landscape. Qualityis primarily a matter of how clearly the distinctivecharacter of a landscape type is expressed in an areaand of the state of repair or condition of landscapeelements and the integrity and intactness of the

landscape.

Landscape value refers to the relative value weattach to different landscape and is the basis fordesignating or recognising certain highly valuedlandscapes. A landscape may be valued for manyreasons, which might include landscape quality,scenic quality, tranquillity, wilderness value,consensus about its importance either nationally orlocally, and other conservation interests andcultural associations.

Landscape sensitivity is the degree to which aparticular landscape character type or area canaccommodate change without unacceptable detrimentaleffects on character. Sensitivity is not absolutebut is likely to vary according to the type of changebeing considered.

Landscape capacity is linked to sensitivity and dealswith the amount of change of a particular type whicha landscape can accept without adverse effects onlandscape character.

Landscape robustness which is another way ofthinking about sensitivity and capacity, in that avery robust landscape will have low sensitivity and ahigh capacity to accept change, while a landscapewhich is not robust will be very sensitive and willnot have much capacity to accept change.

(iv) Sensitivity of the baseline landscape

Understanding the varying sensitivity of differentlandscapes and views to change, and to proposals forwind energy development in general, is important inenabling the significance of a cumulative effect to bejudged, rather than simply its magnitude measured.There is some disagreement within the landscapeprofession over how much can be said about sensitivityin general in the absence of fully detailed proposals.Nevertheless it is considered useful at the baselinestage to draw some broad conclusions. Developmentpolicy in an area, including, for example, regionaltargets for wind related renewable energy productionwill determine how much development (ie. change) isrequired in an area.

Criteria can be identified which can be used asinitial pointers towards aspects of landscapecharacter which may indicate higher or lower levels ofsensitivity towards wind energy development. It isfar from certain, however, that there is a consensuson the links between the presence of certain landscapecharacteristics, and the sensitivity of a particularlandscape to wind energy development.

Each of the individual landscape and visual receptorswill have a different sensitivity to wind energydevelopment. In the case of visual receptors, thiswill partly depend on the 'frame of mind' of thoseenjoying the view. Visitors are likely to be moresensitive than people who gain the view in the contextof work, for example.

3.1.4 Step 3 : Predict the effects and quantify theirmagnitude

The following provides guidance on use of the various toolswhich exist, in practice, to predict and quantify themagnitude of the potential cumulative landscape and visualeffects. The magnitude of an effect is the scale of thechange which occurs. Whether this is a good change or a badchange (a beneficial or adverse effect) is assessed laterwhen conclusions about the significance of effect must bedrawn. Because changes to landscape are largely qualitativerather than quantitative, assessing the magnitude oflandscape effects requires professional judgement. This isjust as much the case in the cumulative assessment of windenergy development where the magnitude of a change tolandscape character may be due to the visibility of turbinesover long distances.

(i) Zones of visual influence

Computer generated Zones of Visual Influence are a keytool in predicting the magnitude of landscape andvisual effects. They provide both an initialimpression of the theoretical extent of theirvisibility and help to identify the specific visualreceptors and viewpoints which may be affected. Theydo, however, have two significant drawbacks:

• they usually omit the screening effect oflandcover• they do not allow for the relationship between

visibility and distance

These drawbacks are magnified in cumulativeassessment.

Cumulative assessment requires the use of compositezones of visual influence. Composite ZVI show thetheoretical visibility of two or more wind energydevelopments. They either indicate the total areafrom which wind energy developments will potentiallybe visible or are able to differentiate, with colour,areas from which different numbers of developmentsmay be simultaneously visible. The drawbacks of ZVIhave two important implications for composite ZVI.If, for example, an area is highlighted from whichmore than one development may be visible:

• if there are more wind energy developments in thestudy it is unclear which of the sites may bevisible.

• it may not be the closest sites which arepotentially visible

Two important variables must be set to produce eithera simple or a composite ZVI;

• the subject of the ZVI; whether it indicatespotential visibility of the blade tip, hub ortower of the turbines and whether it indicatesjust one, several, or all turbines within adevelopment as being potentially visible

• a limit to the distance (or radius) of thepotential visibility

Decisions about how ZVI are to be used, their limitand subject, may change depending on the specificeffect being investigated. The following identifiespoints at which ZVI may be used in a cumulativeassessment and provides guidance on how ZVI can beadapted to provide the most useful information.

1. The preliminary ZVI

The subject of this 'simple' ZVI (ie. notcomposite) is the present proposal only. It canbe used to comprehensively identify all of thelandscape receptors which might experience acumulative effect to which the present proposalmay contribute. It will be most appropriate forthe subject of this ZVI to be just a single bladetip of a single turbine to ensure that it gives a'worst-case' picture.

2. Identification of representative viewpoints

It should be possible to identify all of thelandscape receptors which may be cumulativelyaffected and require detailed investigation priorto the preparation of composite ZVI (see step 1).Nevertheless it can be considered best practiceto prepare composite ZVI to assist in theselection of representative viewpoints. Here thesubject of the ZVI may require the visibility ofhub or tower of several of the turbines. Thiswill help to identify early on accessible andsensitive viewpoints where the most significantsimultaneous visibility may occur. Similarlyplacing limits on the distance of the ZVI foreach site (depending on the height of each) mayhelp identify the key issues within theassessment.

3. Effects on landscape character

Here the total area from which any turbines maybe visible may be as important as identifyingareas of simultaneous visibility. It will beimportant that composite ZVI include visibilityover the longer distance ranges. Generallyspeaking the subject of composite ZVI which arebeing used to predict effects on landscapecharacter should be a significant proportion of asignificant number of turbines at each site.

(ii) Viewpoint analysis

An analysis of different viewpoints in the vicinity ofwind energy developments is an accepted approach toassessing landscape and visual effects. Theviewpoints should ideally be agreed between thedeveloper and the local planning authority.

The choice of viewpoints is often agreed prior to thepreparation of ZVI. In many cases local knowledge mayensure an effective choice, but the use of a compositeZVI to help identify the representative viewpoints canbe considered best practice. Furthermore the use ofcomposite ZVI, with a limit placed on distance, mayassist in identifying those points from whichdevelopments will be simultaneously visible overrelatively short distances . This will help toidentify places from which potential coalescence inthe same field of view might occur.

The final choice should

• Include points from which simultaneous visibilityat close quarters may occur; ie. visible in thesame field of view.

• Include points from which visual coalescence mayappear to occur.

• Include points which are representative of thefull range of potential cumulative landscape andvisual effects.

(iii) Visual Effects

It will be most effective to wherever possible ensurethat all of the viewpoints used in the cumulativeassessment are used also in the of site specific EA ofthe present proposal. The cumulative viewpoints willbe a subset of the site specific viewpoints.

It will be useful to differentiate between viewpointswhich have been chosen to represent landscapecharacter areas, from those which represent a viewenjoyed by a particular visual receptors. Anassessment of the cumulative effects upon a 360o

viewpoint will inform judgements about the magnitude

of change to perceived landscape character.Cumulative visual effects are those which occur withina single field of view. The relationship betweenviewpoints, field of view and visual amenity isdiscussed below.

It may be necessary to illustrate the cumulativeeffects of simultaneous visibility on a 360o viewpoint.If photomontage is used the distortion should be madeclear. A diagrammatic representation may be moreappropriate. A view can be defined as that which isseen within a single field of view. This is generallyaccepted to be between 50 and 70o. Cumulative visualeffects within a single field of view can besuccessfully represented by wireframe or photomontage.Photomontage tend not to be effective representationsbeyond a distance of approximately 7 km.

3.1.5 Step 4 : Assess Significance

The completion of step 3 will have provided a summary of thepredicted extent of wind energy development visibility andits effect on landscape character and on specific individualviews. The significance of these changes will then need tobe assessed. Whatever the magnitude of the effect, itssignificance may be small or great and may be judged to beeither beneficial or adverse. There are two recognisedapproaches; judging significance in relation to the capacityof the landscape to absorb development and identifyingthresholds of change.

(i) Capacity

The capacity of landscapes to successfully absorb windenergy developments, without significant detriment orchange to their character, can be assessed. Definingthe capacity of a specific landscape character will bea matter for professional judgement and there ispresently no consensus over either criteria or on theapplication of the concept of capacity itself.

Assessing the capacity of a landscape for wind energydevelopment is closely related to the definition ofits sensitivity. The presence of existing wind energydevelopments is often perceived to reduce thesensitivity of the landscape. This might beinterpreted as increasing its capacity for furtherdevelopment and would, for instance, be at odds withthe approach adopted by the Countryside Agency inEngland.

The Countryside Agency in England suggest that thecapacity of a landscape is exceeded where it is unableto absorb wind energy developments without significantchange to its essential perceived characteristics(Countryside Agency/SNH 1999). This effectively

defines a single threshold whereby acceptability isDependent on the absence of a change in character.Many would take the view that by the very nature andscale of wind energy development, some change incharacter will usually occur. The Agency approachalso implies that the creation of a 'wind energylandscape' (where wind turbines are the principal anddefining characteristic) will not be acceptable in anycircumstances. The present unfamiliarity of windturbines may result in their being prematurelyidentified as a defining characteristic.

(ii) Thresholds

Increasing numbers of wind energy developments withina landscape are likely to have an increasing effect.It is likely, however, that this relationship will notbe entirely linear (purely additive) and that theprocess of change can be interpreted as a series ofthresholds. Such thresholds can be a useful shorthandfor describing the degree to which wind energydevelopments have become a defining characteristic oflandscape character. The successful and consistentapplication of such an approach will clearly, however,rely on a common understanding of definitions andcriteria. This can be very difficult in practice.

Cumbria County Council suggest that levels of windenergy development fall within one of three stages,separated by two thresholds. These are defined in box3.4.

Box 3.4

Stages of Wind Energy DevelopmentCumbria County CouncilSupplementary Planning Guidance, 1997

Stage Threshold

1. There is a winddevelopment in thislandscape

Wind development becomes asignificant characteristicof the landscapeconcerned.

2. This landscapecontains a number ofwinddevelopments/significant number of turbines.

Wind development becomes

the dominantcharacteristic by whichthe landscape would bedescribed.

3. This is a wind energylandscape.

Stage 2 of the Cumbrian system is arguably very broadand may encompass levels of development of quitediffering significance to landscape character.Similarly, with a division of just three stages, andthe absence of comprehensive criteria, prematureidentification of a 'wind energy landscape' may occur.It is unclear what levels of cumulative effectconstitute the test for demonstrating the creation ofa 'Wind Energy Landscape'. Creation of a Wind EnergyLandscape may have a positive landscape effect in somecircumstances. For these reasons a system ofthresholds which divide the process of change into agreater number of stages, with clearly definedcriteria linked to predicted cumulative effects, maybe useful. Although criteria may differ depending onthe specific character of a given landscape, a 'WindEnergy Landscape' is possible if all the followingoccur:

• Wind energy developments begin to visuallycoalesce from some viewpoints

• Simultaneous visibility within the same field ofview frequently occurs

• Wind energy developments are frequentlysimultaneously visible over relatively shortdistances where they may be said to dominate theview

• Visibility from linear routes is frequent withlittle of a route outside of the visual influenceof wind energy developments.

The above are illustrative examples and should not betreated as in any way definitive. It is likely,however, that the perception of a 'wind energylandscape' is Dependent on extensive simultaneousvisibility of developments.

It will also finally be necessary to make a judgementover whether the creation of a wind energy landscapein the specific circumstances is beneficial oradverse. This will depend on the specific character,condition, quality and scenic value of the baselinelandscape and will always involve subjective judgementregarding the beneficial contribution that wind energystructures can have.

(iii) Weather conditions

Wind energy developments often occur in areas whereweather conditions are changeable and unpredictableand where visibility can be severely reduced for muchof the time. As a principle, whilst the assessment ofeffects always assumes a 'worst case scenario'reference to average visibility with respect toweather etc. should be made. Visibility studiesshould always therefore assume good normal levels ofvisibility. Although the assessment may wish tohighlight the relative infrequency of simultaneousvisibility, this is unlikely to materially affect thejudgement of its significance.

3.1.7 Best Practice Conclusions

The preceding guidance on the assessment of the cumulativeeffects of wind energy development can be summarised in thefollowing pointers towards best practice as set out in box3.5.

Box 3.5

Best practice in the assessment of cumulative effects

• Character and views

Always differentiate between cumulative landscape andvisual effects.

• Simultaneous and sequential visibility

Consider effects caused by both simultaneousvisibility and sequential visibility.

• Intrinsic values

Pay attention to the values and experiences withwhich the landscape may be associated whilstacknowledging the subjectivity involved.

• The study area

Do not confuse the area over which a proposal maycontribute to a cumulative effect with either itstheoretical zone of visual influence or an arbitrarycircle.

• Significant effects

Initially carry out a comprehensive review of all ofthe cumulative effects to which the present proposalmay contribute, but subsequently focus the detailedinvestigation on those issues which are likely to bemost significant and practicable to assess.

• The baseline

Where wind energy developments already exist, ensurethat their effect on the landscape's sensitivity islogically and carefully discussed and that anunderstanding of how wind energy development hasalready changed the landscape is provided.

• Future developments

Make a judgement about which reasonably foreseeabledevelopments should be included in the assessment(each landscape area, route or view on its own terms)

to strike the optimum balance between practicableassessment and meaningful results.

• Representative viewpoints

Prepare ZVI, composite ZVI and limited distancecomposite ZVI in advance of selecting viewpoints toensure they are representative of all potentialissues.

• An integrated approach

Ensure the cumulative viewpoints are all also used inthe site specific assessment.

• Photomontage

Wherever possible, photomontage should represent asingle field of view. (Where panoramas have beenartificially flattened, this must be clearly stated).

• Capacity and thresholds

Explicitly state the criteria and definitions used todraw conclusions about thresholds and the capacity ofthe landscape to absorb wind energy developments.

• Wind energy landscapes

Ensure that judgements of significance areuniversally applicable and would be sensitive to allpossible levels of wind energy development. Ensurethat a 'Wind Energy Landscape' is not prematurelypredicted.

BIRDS

3.2 THE ASSESSMENT OF CUMULATIVE EFFECTS ON BIRDS

3.2.1 Understanding the Cumulative Effects of Wind Energy on Birds

As elsewhere in the guidance the term 'effect' is taken toinclude both positive and negative consequences, qualifiedwhere appropriate by the terms 'adverse' or 'beneficial'.An example of beneficial effects upon birds might arisethrough habitat enhancement at a large moorland wind farmsite. Heather moorland restoration might result in a netbenefit to red grouse populations, by more than compensatingfor the loss or reduction in size of breeding territoriesthrough direct habitat loss, or of individuals throughcollision. This approach to mitigation (see 3.2.2 iv)should not be pursued adjacent to sites protected under theHabitats Directive and UK regulations.

(i) What does the section of the guidance cover?

The primary aim of this section is to outline thecircumstances where cumulative effects upon birdsmight be expected to arise, and provide broad guidanceon a number of issues.

(ii) What baseline should be used?

For birds there is great difficulty in reconstructinga retrospective baseline for pre-constructionconditions. Therefore assessing the effects ofdevelopment in ornithological terms (cumulative orsite specific) is difficult without an adequate andaccurate pre-construction baseline. As a result, itis not possible to conclude whether or not cumulativeornithological effects have occurred to date as aresult of wind farm construction and operation in theUK since any such effects may remain undetected.Nevertheless, there appears to be general agreementamongst practitioners that there is no evidence todate for cumulative effects of wind farms upon birdshaving yet arisen at either individual, pair orpopulation level in the UK.

(iii) What are the steps needed?

A general procedure should start with defining theparticular species for consideration, progressingthrough a consideration of where (includinggeographical limits definition) and how the assessmentshould be undertaken, followed by the analysis offindings from existing studies using methodologiesagreed with statutory consultees and the RSPB, andconcluding with identification of the effects atdifferent levels.

BIRDS

Box 3.6

The Steps:

1. Define particular species for CA2. Consider where and how the CA should beundertaken3. Analyse findings from existing studies4. Use methodologies agreed with statutoryconsultees and the RSPB5. Conclude what are the effects at differentlevels

It has not been possible to reach consensus uponwhether or not all ornithological assessments of windfarm proposals should include cumulative effects.Most practitioners undertaking such assessments forwind farms believe that it should only be undertakenon sites with potential for adverse effects for birds.This suggests that the cumulative assessment isgenerally undertaken only on sites where site-basedassessment reveals the potential for adverse effects,such as particular multi-site situations and withcertain defined key species (see 3.2.2 below).However, practitioners should be aware that someeffects might arise only in a cumulative context. Assuch, cumulative assessment should be regarded as anadvanced phase of general ornithological assessmentmethodologies (eg. SNH/SBWEA) rather than an integralpart of all ornithological assessments contributing toeach and every assessment for wind farms.

3.2.2 Good Practice Guidelines for Birds

The assessment of cumulative effects upon birds is highlyspecialised and complex. As part of the production of theseguidelines a group of ornithologists with experience ofstudying wind farm effects was set up to consider theapplication of current methodologies and consider their rolein the cumulative scenario. The work is written upseparately (Gill, 1999). Monitoring of bird populations andmortality rates are central to the issue and a need forfurther work and co-ordination of existing data has beenidentified.

(i) What species should be considered?

Cumulative assessment is especially relevant for keyspecies whose conservation importance, ecologicalattributes and/or particular sensitivities to windturbine effects make them especially vulnerable.

Effects may arise at either or both of two levels:

BIRDS

• Range of individual pair or breeding unit (eg.red kite, hen harrier, golden eagle, peregrinefalcon, merlin, red throated diver)

• Range of breeding or wintering population (eg.Greenland white-fronted goose, Greenland barnaclegoose, Svalbard barnacle goose, bean goose, henharrier, golden eagle, golden plover, andpossibly curlew and lapwing).

Attributes of species populations increasing theirvulnerabilities to cumulative effects, include largehome/feeding range, other sources of habitat loss,rarity and/or scale and rate of decline, limitedcapacity to replace 'lost' individuals and regularityof use of flight lines.

Sensitive species lacking special protective measuressuch as curlew, some ducks, geese and waders; mightneed to be considered as part of cumulative assessmentin some situations. Sites with special concentrationsof birds which might give rise to an exceptional riskto any species should also be considered.

General species predictions about risks should not bemade - these are site-specific and may be critical atsome times, not others.

However an initial list of key species to beconsidered for ornithological CA should includeGreenland white-fronted goose, Greenland barnaclegoose, svalvard barnacle goose, bean goose, red kite,merlin, short eared owl, clough, raven, hen harrier,golden eagle, peregrine falcon, red throated diver,black throated diver, great skua, arctic skua,dolterel, golden plover and dunlin. As a precautionall EC birds Directive Annex I and Wildlife andCountryside Act (W&CA 1981) Schedule 1 species shouldbe included.

(ii) When should Cumulative Assessment be undertaken andwhat is the scope?

Cumulative Assessment should generally only berequired in multi-site situations where site-basedadverse effects are predicted (see 3.2.1) though theRSPB have pointed out that for birds and some floracumulative effects may arise where there are no suchpredictions.

The geographical boundary for the cumulativeassessment of each species should be separatelydefined rather than using a site-based limit, eg. 500to 800 metres from outermost turbines for wadingbirds.

BIRDS

Forestry and other land use developments which affectbirds in similar ways (eg. habitat displacement) havethe potential to add to or combine with the effects ofwind farms, and might therefore need to be included inan ornithological assessment. Whether other suchdevelopments are already affecting the species underexamination in similar ways should be considered.

(iii) How should delayed effects be considered?

Studies should be designed to allow for delayedresponses by continuing monitoring over several yearsbefore and after development. Depending upon how sitefaithful an individual bird is, and the availabilityof suitable alternative habitat nearby, response todisturbance may be delayed. Such monitoring shouldonly be continued where analysis of initial reportsshows a significant need to do so.

Displacement may cause knock-on effects onproductivity, body condition, survival, as well aspopulation size. Detailed studies (where necessary)should attempt to quantify these. If it is difficultto establish where displaced birds have moved to, itmay be simpler to assume a worst case scenario thatdisplaced birds have either been lost from thepopulation, or will make a reduced contribution tobreeding or survival.

(iv) What about mitigation?

Consider the potential to improve habitat quality inimpoverished habitats as mitigation of any predictedadverse cumulative effects. Consider also theavailability of suitable alternative habitat in thevicinity of the wind farm. Do not copy any sitespecific mitigation measures unless the sites aredirectly comparable or until the efficacy of suchmeasures has been established.

Collision risk should always be minimised by sitingand design rather than habitat enhancement elsewhere.

(v) How can collision mortality rates be predicted?

Extrapolations to predict bird collision mortalityrates associated with regional wind/renewables/CO

2

reduction targets (see 1.2.1) might help minimise anycumulative effects in the future. These should bepresented as average collision mortality rates withconfidence intervals for the region and form acomponent of Regional Strategies on Sustainability.Environmental Assessments which predict some collisionmortality should compare these predictions to averagerates across the region.

(vi) Monitoring

BIRDS

Long term monitoring may be needed at a representativegroup of wind farms to properly evaluate gradual orincremental change in longer lived bird species.Since monitoring after construction is an onerousburden on wind energy both as an industry and asindividual developers it is essential that these sitesare very carefully chosen, rather than arising as theyoften do through uncoordinated negotiations betweendeveloper, consultees and planning authority. It isimportant that sufficient time is allowed to monitorbird populations. The minimum would be a full yearcycle of site occupancy. There is a need for moredata for species which do not breed every year, havealternative nest sites or have irregular flight-lines(e.g. some geese).

(vii) Predictive Models

Where predictive models (e.g. Population ViabilityAnalysis) are employed to explore effects of wind farmdevelopments upon mortality rates and breeding successthey should use appropriate data. The use ofhypothetical estimates of collision rate for raptors,guessing of estimates of survival for rare birds andthe use of data from small samples not typical of thespecies’ range are to be discouraged.

GLOSSARY

Annexe 1

GLOSSARY

Additive effectsEffects which increase in direct proportion to the number of wind

energy developments

CharacterA distinct, recognisable and consistent pattern of elements in

the landscape (see box 3.3).

CharacteristicsThose elements that in combination create the distinctive

character of an area.

CharacterisationThe process of identifying areas of similar character,classifying and mapping them and describing their character.

Composite zone of visual influenceOverlapping zones of visual influence of more than one windenergy development

Cumulative effectsThe combined effects of extended or additional wind energydevelopments

ElementsIndividual components which make up the landscape eg. woodland,moorland, scree slopes.

FeaturesParticularly prominent or eye-catching elements, like treeclumps, industrial buildings, pylons, roads, housing, churchtowers, or wooded skylines, etc.

Field of viewThe view which is seen in a single direction - generally agreedto be between 50 and 70o

Landscape capacity(see box 3.3)

Landscape quality(see box 3.3)

Landscape sensitivity(see box 3.3)

Landscape value(see box 3.3)

Present proposalThe proposed wind energy development which has triggered thecumulative assessment

GLOSSARY

GLOSSARY

Sequential visibilityVisibility from different places as one moves through thelandscape. Speed, and therefore time between viewings andviewpoints will be an important consideration.

Simultaneous visibilityVisibility of more than one wind energy development from a singlefixed point

Site specific effectsThe effects of the individual present proposal

Temporal limitsThe period of change over which cumulative effects may arise

Threshold effectsAn effect which does not necessarily increase in directproportion to the number of wind energy developments

Zone of visual influenceThe area from which a wind energy development is theoreticallyvisible

BIBLIOGRAPHY AND REFERENCES

Annexe 2

REFERENCES AND ADDITIONAL READING

This document should be read as a supplement (which focusesentirely on additional cumulative issues) to many of thefollowing publications. These either provide a basis ofunderstanding upon which the content of this guidance has beenbuilt, or already provide the assessor with useful informationwhich can be applied in the cumulative context. The list alsocontains references for other outputs of the CEWT project.

BWEA (1994) Best practice guidelines forwind energy development. BritishWind Energy Association . November1994.

CCW (1998) Landmap : The Landscape assessmentand decision making process. Drafthandbook for consultants.Countryside Council for Wales.

Countryside Agency/SNH (1999) Interim Landscape CharacterAssessment Guidance. CountrysideAgency and Scottish Natural Heritage.

Countryside Commission (1993) Landscape Assessment Guidance(CCP 423). Countryside Agency,Cheltenham.

DETR (1999a) Environmental AssessmentRegulations. Department of theEnvironment Transport and theRegions. HMSO.

DETR (1999b) A better quality of life : Astrategy for sustainable developmentfor the United Kingdom. Departmentof the Environment Transport and theRegions. HMSO.

DoE (1997) Planning Policy Guidance Note 7. TheCountryside and Rural Economy. HMSO.February 1997.

DoE (1993) Planning Policy Guidance Note 22.Renewable Energy. HMSO. February1993.

DTI (1999) New and Renewable Energy - Prospectsfor the 21st Century. Department ofTrade and Industry. HMSO. March1999.

ETSU (1996) The assessment and rating ofnoise from wind farms. The working

BIBLIOGRAPHY AND REFERENCES

group on noise from wind turbines.ETSU-R-97. September 1996.

GAG/LUC (1997) What Matters and Why. EnvironmentalCapital: A New Approach. Aprovisional Guide. Land UseConsultants. August 1997.Countryside Agency, Cheltenham.

Gill (1999) Cumulative Effects of WindTurbines - Report on results ofconsultations on cumulative effectsof wind turbines on birds. Report toETSU. November 1999.

Gill, J.P., Townsley, M & Review of the impacts of windfarms and other aerial

Mudge, G.P. (1996) structures upon birds. ScottishNatural Heritage Review No. 21.

Landscape Design Associates (1999) Cumulative Effects of WindTurbines - Report on the preparationof a planning tool by means ofconsensus building. Report to ETSU.W/14/00538/00/00. December 1999.

Landscape Institute/ Guidance for landscape andvisual impact assessment.

Institute of EA (1995) E & FN Spon. NB: Revision due2000.

New Perspectives (1999) Cumulative Effects of WindTurbines - Report on qualitativepublic attitude research in MidWales. Report to ETSU. July 1999.

SNH (1999) Exploration of the capacity oflandscape character types toaccommodate wind energy development.Unpublished consultant report toScottish Natural Heritage.

Richard Wakeford (1999) The development of theEnvironmental Capital Approach.Speech to LGA seminar, 21.9.99.Chief Executive - The CountrysideAgency.

CONSENSUS BUILDING PROCESS

Annexe 3

THE CONSENSUS BUILDING PROCESS

Central to the development of the CEWT guidance has been itsadoption of a consensus-building process amongst stakeholderswith an interest in the future of wind energy development. Fulldetails of this process are recorded in a separate report byLandscape Design Associates (Landscape Design Associates, 1999).The following provides a short overview of the process:

• Project Team: The project team comprised LandscapeArchitects (Phil Black and Colin Goodrum of Landscape DesignAssociates), an Ecologist (Paul Gill of EnvironmentallySustainable Systems), a Wind Energy Developer (Chris Shearsof Renewable Energy Systems) and a local authority Planner(David J Ellis of Burnley Borough Council). Workshops wereled by a specialist consensus-building and conflictresolution organisation (Robin Sadler and Liz Spencer of NewPerspectives). The project team was supported by a steeringgroup which included Richard Boud and Tony Duffin of ETSU.

• Call for Contributions: Invitations to contribute to theproject were sent to approximately 300 organisations(identified by the project team) and published as a pressrelease. The Call for Contributions was carefully worded toensure that stakeholders were given an opportunity to helpdefine the scope of the project and identify what wasrequired of the final guidance.

• Written Contributions: A written contribution to theproject was received from approximately 100 organisations.These were reviewed to identify the 'key players' and thosewith most experience of tackling the issues of cumulativeeffect.

• Stakeholder Workshops - First Discussions: A group ofapproximately 30 stakeholders attended two workshops whichaimed to identify the scope and content of the requiredguidance.

• Public Focus Groups: Three focus groups were held in MidWales (led by Robin Sadler and Liz Spencer of NewPerspectives) to explore different groups' perspective onthe issues. The findings of the Focus Groups are presentedin a separate report (New Perspectives, 1999).

• Electronic Discussion Group on Birds: A separate electronicdiscussion group on birds (led by Paul Gill ofEnvironmentally Sustainable Systems) was held to furtherexplore specialist and technical issues. The findings ofthis group are presented in a separate report (Gill, 1999).

• Second-Stage Stakeholder Consultation Workshop: A singleworkshop presented issues papers on the key findings of theCEWT project to approximately 20 stakeholders. The final

CONSENSUS BUILDING PROCESS

form of the guidance was built upon these issues papers andthe feedback received from stakeholders.

• Final Consultation Draft: A final draft of the guidance wascirculated to approximately 40 key stakeholders -principally those who had attended any one of the threepreceding workshops.

Written responses to the Consultation Brief were reviewed and thedocument amended in response to common concerns.