Abstract
This Evidence Review Note (ERN) provides comprehensive guidance on assessing the impacts of offshore wind farm (OWF) projects on the marine historic environment. Drawing on evidence from over 76 Environmental Impact Assessments (EIAs), along with input from regulators and heritage professionals, the ERN aims to support more effective, proportionate, and consistent EIAs. It should be read alongside Evidence Review Note: Environmental Impact Assessment, which provides complementary guidance on the overarching approach to EIA.
This ERN identifies significant variation in scoping practices, chapter structure, terminology, and impact reporting across OWF projects, hindering comparability and clarity. Despite this, evidence confirms that well-designed mitigation measures have successfully reduced significant adverse impacts to negligible or minor levels in recent projects. To address these challenges and build on good practice, the ERN gives the following recommendations:
- Standardisation of Scoping: Adopt a consistent, evidence-based approach to EIA scoping using a three-tier categorisation (Categories A–C) of impacts. This will improve efficiency and focus assessments on likely significant effects.
- Consistency and Clarity of Reporting: Use standardised chapter structures and terminology to enhance accessibility and comprehension. Ensure signposting is clear, and aligned with planning policy terminology. This will improve engagement among non-specialist stakeholders.
- Proportionate Reporting: Be concise and focus reports on significant effects. Move technical detail such as historic baseline information to appendices. Use digital tools, such as GIS-based maps, interactive visualisations and web-based reporting to enhance clarity and usability.
- Pre-Application and Pre-Construction Survey Requirements: Informed by pre-application advice, developers will actively manage risks in their decisions about the extent and resolution of surveys at successive stages of the development process. Use a Design Envelope proportionately, and balance flexibility against the need for understanding among decision- makers, so they can assess risks to the marine historic environment.
- Monitoring and Enforcement: Conditions, commitments and requirements secured through planning and consenting must be enforceable and underpinned by robust, standardised monitoring frameworks integrated with CEMPs. Post-consent reporting and archiving must demonstrate that mitigation has been effective, with data deposited in national archives and aligned with national research frameworks.
- Strategic Approach to Risk Assessment: Create greater alignment between project-level assessments and wider strategic objectives, including cumulative effects across multiple OWF projects. This will improve efficiency and provide better context for decision-making.
- Use of Cumulative Effects Assessment (CEA): Adopt a standard methodology for assessing cumulative impacts on the marine historic environment, particularly for areas of known archaeological sensitivity and repeated development.
- Acknowledgement of Beneficial Effects: Offshore wind developments can enhance knowledge of the marine historic environment through survey, investigation, and discovery. Acknowledge and record these positive contributions consistently.
By implementing these recommendations, the offshore wind sector can reduce costs, increase certainty, and streamline the consenting process. Clearer, more consistent and proportionate assessments will strengthen engagement and promote good design. It will ensure the UK’s marine heritage is protected along with its ambitions for clean energy growth.