Background

On 14 January 2025, planning permission was granted for a wind farm which comprised eight wind turbines and their associated infrastructure. Neither the application nor its environmental statement included the environmental implications of the future grid connection required to connect the power generated by the wind turbines to the local electricity distribution network.

An objector during the planning process raised an objection that it was wrong for the applicant not to have included the grid connection in the scheme’s EIA documents. The reporter (the Scottish equivalent of a planning inspector) dealt with the issue briefly and concluded that the grid connection need not be included since (1) the grid connection would be subject to its own evaluation when proposed, (2) the grid connection did not form part of the current proposals, and (3) there had been no attempt on the part of the applicant to avoid the need for an EIA by separating the development into separate parts.

The appellant, Raeshaw Farms Ltd, operates a farm and estate close to the proposed wind farm development. The appellant challenged the grant of planning permission primarily on the basis that when assessing the impact of the wind farm, the reporter should have found that the wind farm and its grid connection constituted a single development.

Under Regulation 3 of the Town and Country Planning (Environmental Impact Assessment) (Scotland) Regulations 2017, planning permission must not be granted unless an EIA has been carried out in respect of that development. A failure to assess the entirety of a development in an EIA would therefore render the grant of permission unlawful.

The grounds of appeal

The appellant brought the appeal on four grounds.

Ground 1 was an irrationality challenge. The appellant contended that the reporter irrationally took into account the benefits of the development that could only be realised upon installation of a grid connection, while at the same time failing to take into account the disbenefits (landscape and visual impact).

Ground 2 was that the totality of the development had not been considered since no EIA had been carried out with regard to the grid connection.

Ground 3 contended that the reporter erred in his dismissal that the grid connection was not part of the overall scheme.

Ground 4 was that the reasons given by the reporter were inadequate.

The Court of Sessions’s Decision

Lady Wise allowed the appeal on all four grounds and quashed the decision to grant planning permission. The scheme was sent to a different reporter for a fresh decision.  

The discussion below focuses primarily on the issues arising under grounds 2 and 3, while providing a brief summary of the Court’s findings on grounds 1 and 4.

Grounds 2 and 3 are intrinsically linked. The judgment on these grounds has a narrow and a broad aspect. Narrowly, was the reporter’s decision correct? More broadly, what is the correct approach to be taken for projects such as wind farms generally?

The narrow issue 

Lady Wise considered that the reporter had failed adequately to assess the development’s scope in two respects. First, he failed to address the critical issue of whether the wind farm and associated grid connection constituted a single development for the purposes of the EIA. The court found that the reporter erred in relying on the fact that the grid connection would “be subject to its own evaluation” when it was eventually proposed and was “not part of the current proposals”. There had been no evaluation on the part of the reporter to ascertain whether the windfarm and associated grid connection were part of a single development for the purposes of an EIA ([43]).

Second, the reporter had erred in his approach to ‘salami-slicing’. Salami-slicing is the term for where a single development is artificially split up into smaller individual projects, which has the effect of circumventing the EIA process. Lady Wise noted that the reporter had erred in concluding that there was no issue of salami-slicing since the development had not been deliberately split up to avoid the assessment under the EIA. The court provided a useful reminder that ‘salami-slicing’ is not concerned with intention but rather was the actual effect that a development is likely to have on the environment ([43]-[44]).

The broader issue

The judgment at [18]-[41] provides a helpful overview of the approach taken not only by the UK courts but also by the Irish and EU courts to assessing what is and is not part of the development for EIA purposes.

The court affirmed that the decision-maker must not confine themselves to how an application is framed in considering what is, or is not, part of the development. The reporter had erred in this respect, effectively taking the applicant’s proposal at face value. A key question for a decision-maker is the degree of connection between the development and its putative effect ([46]).

However, the judgment steers clear of giving more detailed guidance and the court intentionally did not make any sort of finding as to “whether in fact the project under consideration constituted a single project for the purposes of assessing its environmental impact; that has yet to be properly determined. Such a determination properly falls to be made by the appropriate authority, the respondents” ([47]).  

Lady Wise noted that this position was different to the approach taken by the Irish courts discussed at ([33]-[40]) of the judgment. The Irish courts have treated the issue of whether a grid connection and a wind farm are a single development as an “issue of principle” ([48]). The court did, however, find a similar focus between the Irish and UK approaches on the need for “such a fact-specific evaluation before any decision can be made” ([48]).

The respondent’s argument that since wind farms and grid connections have separate project descriptions under the annexes in the directive, they can be treated separately, was soundly rejected by the court. The court's focus was not on abstract descriptions but on the correct approach to the particular scheme in issue.

Lady Wise also rejected the respondent’s second line of argument that a ‘staged-approach’ was appropriate. A staged approach is where two connected projects may proceed separately, and their cumulative effects may be assessed either in two stages or at the second stage, but as soon as the cumulative effects can be identified for meaningful assessment.

The court had before it two affidavits on whether it was appropriate or possible to assess the likely significant environmental effects at the initial application of planning permission. The court, once again, focused on whether, in the current circumstances, it would have been realistic to have assessed the impact. The court agreed with the appellant that it would not have been unrealistic in the circumstances for the interested party to have assessed the impact of the grid connection at an earlier stage since the grid connection at the wind farm was known ([51]-[52]).

On ground 1, Lady Wise agreed with the appellant that it was irrational for the reporter to have placed considerable weight on the wider benefits that would result from the operation of the wind farm once connected to the grid. Whilst, at the same time, saying that the grid connection, and its disbenefits, would be considered at a later date ([56]).

On ground 4, the Court found that the reporter’s reasons were inadequate as they largely contained assertions and conclusions and were bereft of reasoning directed at the point in issue ([54]).

Commentary

The judgment provides a number of key takeaways relevant to those considering EIA and wind farm projects in particular:

First, the decision proceeds on the basis that there is no blanket rule or approach as to what constitutes development for the purposes of EIA. The court refused to take such an approach, and there is no ‘in principle’ rule, unlike the Irish case law, about what should or should not be included when progressing an EIA for a wind farm. The court perceived that there would be certain scenarios where it would be appropriate to include a grid connection, and others where it would not. The court’s decision, in that respect, departs from the reasoning of the majority in R (Finch) v Surrey County Council [2024] UKSC 20 as regards the different question of whether downstream emissions are an indirect effect of a project. The majority in Finch adopted an objective approach when assessing the environmental effects of a project; this approach was intended to ensure consistency among decision-makers when assessing the effects of similar projects. Accordingly, it seems that a decision-maker must take divergent approaches at the different stages of an EIA. First, a subjective approach in deciding what the development itself is, and then an objective approach in deciding what is and is not an effect of that particular project.

Second, and related to the above, the decision of what is or is not part of the development is squarely in the hands of the decision-maker. This evaluative exercise is a matter of planning judgment, and the court will not substitute its views for those of the decision-maker. Nor would the court pre-empt the judgment of the decision-maker. It does, however, leave scope for different opinions on the same project by different decision-makers. Inconsistency, it seems, is welcomed at the initial stage of assessing the environmental impacts of a development.

Third, for promoters of wind farms and interested third parties, the judgment demonstrates the importance of considering the whole of the development from the outset. It is not enough, at a planning inquiry, for a promoter to assert that the future grid connection will be considered later as part of a separate application, or that it is too uncertain at this stage. In fact, the court cautioned that where a developer wished to argue that the grid connection was too uncertain, such an argument was “rather suggestive of permission being sought prematurely”. Similarly, the court cautioned that it is no longer enough to assert that project splitting is justified solely by the expediency of assessing the environmental impacts of constructing a wind farm before the grid connection details are available ([53]).  

It may be worthwhile, alongside this case, to read the recent judgment of Mould J refusing permission to apply for judicial review in R (Against Sizewell C Limited) v Secretary of State for Energy Security and Net Zero [2025] EWHC 3460 (Admin). The judgment provides a helpful example of where it was found to be rational for the decision-maker to adopt a staged approach in assessing the impacts of a development. The case concerned whether, under the Conservation of Habitats and Species Regulations 2017, the potential future use of overland flood barriers and their impact should have been assessed when development consent was granted for Sizewell C. The circumstances of the two cases are somewhat different, but, when read together, they reinforce the fact that the court affords a decision-maker a large degree of latitude in deciding what is or is not part of a development, provided that that conclusion is adequately reasoned.

Fourth, what factors could lead to the grid connection being rightfully left to a later assessment is left unanswered. Lady Wise commented that “other factors could have militated against a conclusion that the scheme constituted a single project” ([46]). While in the present case the grid connection for the windfarm was known, it is not difficult to imagine a scenario in which a grid connection had not been secured, would not be secured for some time, and the form of which (i.e., whether overhead or underground cables) was genuinely unknown ([51]). In such a scenario, an applicant may well wish to argue that the grid connection could be considered separately.

Finally, while this decision concerned wind farms, it offers guidance for any development with multiple components. The best approach, where there is any doubt, is likely to be to assess the cumulative environmental impacts of the whole of the development to the full extent possible as part of the application and consideration of the first stage.