The Raeshaw Farms decision highlights key EIA considerations for renewable energy developments and grid connections, and what they mean for developers in practice.

Published: 28 October 2026
Authors: Jemma Hughes

Earlier this year the Court of Session issued a decision that has highlighted the importance of determining whether a renewable energy development and its grid connection should be treated as separate or connected projects for environmental impact assessment purposes. In this article we look at the key considerations for developers and what the decision could mean in practice.

In Raeshaw Farms Limited v Scottish Ministers and Energiekontor UK Ltd [2026] CSIH 10, the Inner House of the Court of Session highlighted the importance of identifying the project for the purposes of environmental impact assessment (EIA). The case was concerned with a challenge to an appeal decision to grant planning permission for the proposed Wull Muir Wind Farm. A key question was whether the wind farm and its grid connection were separate projects, or a single project requiring an EIA of the wider scheme. Whilst the Court stressed that the decision on what constituted the project was one for the decision maker and not the courts, it decided that the Reporter had not undertaken an adequate, fact-specific evaluation of whether Wull Muir Wind Farm and its associated grid connection formed one project or two separate projects for EIA purposes.

The Wingfield factors

The Court highlighted the non-exhaustive list of factors for identifying the project identified by the High Court in R (Wingfield) v Canterbury City Council [2020] JPL 154 (the Wingfield Decision). These include:

• Common Ownership: Where two sites are owned or promoted by the same person, this may indicate that they constitute a single project.
• Simultaneous Determinations: Where two applications are considered and determined by the same committee on the same day and subject to reports which cross refer to one another, this may indicate that they constitute a single project.
• Functional Interdependence: Where one part of a development could not function without another, this may indicate that they constitute a single project.
• Stand-alone Projects: Where a development is justified on its own merits and would be pursued independently of another development, this may indicate that it constitutes a single individual project that is not an integral part of a more substantial scheme.

Separate projects

Where in terms of the Wingfield factors it could be concluded that the projects are separate then no cumulative environmental assessment of the grid connection is required at the renewables project stage.

Connected projects

If the projects are considered connected and the grid connection route is known then the EIA should assess the cumulative impacts of both projects. In circumstances where the projects are connected but a connection route may not be fully known then the ‘realistic, worst case’ grid connection corridor is assessed applying the so-called ‘Rochdale Envelope’. Further guidance is available from the Scottish Government, Nationally Significant Infrastructure Projects guidance and the UK Government EIA guidance.

This allows a decision maker to determine that a renewables project and the grid connection project are connected projects and at least a partial assessment, based on the information available at the time, of the cumulative impacts of the grid connection will be required.

To assist the decision maker being comfortable with taking a Rochdale approach we could propose a Grampian Condition:

• no development above [specified stage] shall commence until details of the proposed electricity grid connection serving the development have been submitted to and approved in writing by the local planning authority

• the submitted details shall:

  • demonstrate that the proposed grid connection falls within the design parameters and environmental envelope assessed in the Environmental Statement and supporting environmental informationaccompanying the application
  • demonstrate that no materially new or materially different likely significant environmental effects would arise, either alone or cumulatively with the development hereby permitted, beyond those previously assessed by the local planning authority in determining this application
  • identify any mitigation measures necessary to ensure that the environmental effects of the development and grid connection remain within the scope of those previously assessed

• the development shall thereafter be carried out in accordance with the approved details