The expansion of offshore wind is accelerating, driven by Europe’s ambitions to achieve climate neutrality while reducing dependence on fossil fuels. But as deployment increases, so does the complexity of the decisions involved. Ensuring sustainable offshore wind farm (OWF) development requires a deeper understanding of environmental, social and economic impacts throughout the entire project life cycle, from site selection to decommissioning.
A variety of assessment tools currently exist. To support the development of the SUSTAINOW tools, a review of existing tools was necessary to identify how, and to what extent, these support sustainability outcomes, ultimately providing a basis for identifying gaps and opportunities for improved decision-making support.
Summary and Conclusions
Table of contents
1Purpose and scope
This report provides a review of tools used to assess and support sustainability in offshore wind planning and design. It contributes to SUSTAINOW’s aims by clarifying existing tools, their function in practice and their sustainability scope.
The analysis combines:
- A conceptual framing of decision-making in OWF development.
- A mapping of assessment tools used in general practice and across selected countries (Estonia, Portugal, Spain, and Denmark).
- A systematic assessment of the sustainability scope of these tools.
- A review of related tools under development in European research and innovation projects.
2Conceptual framing: OWF phases and decision-making
The report adopts a life-cycle perspective structured around seven phases:
Across these phases, decision-making is characterised by varying:
- Levels of strategic influence.
- Degrees of reversibility.
- Capacity to affect long-term sustainability outcomes.
The greatest opportunities to influence sustainability come during the early stages of offshore wind farm development, particularly when selecting sites and designing tenders. Decisions made at this stage shape many aspects of a project’s future. Although later phases offer less room for change, they remain important for improving implementation and responding to new challenges. Looking ahead, repowering and decommissioning will also play a growing role in supporting circularity and reducing long-term environmental impacts.
3Assessment tools in OWF practice
The report identifies and analyses a set of core assessment tools applied in OWF planning and development. An overview of these tools is provided in the table below:
| Category | Tool name |
|---|---|
| Holistic assessment tools |
Environmental Impact assessments (EIA) Strategic Environmental assessment (SEA) |
| Other assessment tools in SUSTAINOW project scope |
Life cycle assessment (LCA) Cumulative impact assessment (CIA) Social impact assessment (SIA) |
| Assessments under nature and water-related EU Directives and transboundary processes |
Appropriate assessment (AA) under the Habitats Directive
Assessment under the water framework directive (WFD)
and marine spatial framework directive (MSFD) Transboundary impact assessment (TIA) under the Espoo Convention |
| Additional technical or analytical tools for OWF development | Examples: Modelling tools, GIS-based tools, economic analyses, feasibility studies. |
| Upcoming tools under development in research projects | Examples: Data spaces, multi-use platforms, digital twins |
These tools operate within a multi-level regulatory framework, primarily defined by EU directives and international conventions, complemented by national implementation practices.
A key finding is that SEA and EIA constitute the backbone of assessment practice, while several other assessments – particularly those related to biodiversity, water, and marine ecosystems – are typically embedded within SEA and EIA processes rather than applied independently.
Cross-country comparison indicates both convergence and variation:
- A shared reliance on SEA and EIA across all cases.
- Differences in the sequencing and integration of tools.
- Limited and uneven application of LCA and SIA.
- Variable treatment of cumulative and transboundary effects.
4Sustainability scope of assessment tools
The sustainability scope of the identified tools is analysed using two complementary perspectives:
Coverage of sustainability factors
The analysis shows that existing tools collectively address a broad range of environmental, social, and socio-economic factors, including biodiversity, climate, water, human health, and socio-economic activities.
This analytical framework builds on the environmental concept defined in EU SEA and EIA directives and further operationalised in recent methodological developments, including its implementation in the Danish Environmental Assessment tool. This concept reflects an integrated understanding of sustainability, spanning environmental, social, and socio-economic dimensions.
The analysis shows that the currently legislatively required tools differ in nature: Some of the tools have a narrow focus in terms of sustainability, whereas other tools have a broad scope (e.g. the EIA and SEA directives).
Mitigation and enhancement
The analysis identifies a clear distinction between mitigation-oriented and enhancement-oriented contributions to sustainability.
Across the assessed tools:
- Mitigation is systematically embedded and often mandatory, particularly within SEA, EIA, and directive-based assessments.
- Enhancement is not systematically required and is addressed inconsistently, typically depending on project-specific approaches or voluntary tools
Regulatory tools are therefore effective in:
- Identifying and reducing negative impacts.
- Ensuring compliance with environmental standards.
- Managing risks.
However, they appear less effective in:
- Systematically identifying opportunities for positive sustainability outcomes.
- Supporting proactive improvements.
- Enabling system-level optimisation
Tools such as LCA and SIA demonstrate potential to support enhancement through lifecycle optimisation and social value creation, but their application remains limited and not structurally embedded in decision-making processes.
5 Tools under development in European research and innovation projects
In addition to tools currently used in OWF planning practice, a growing number of European research and innovation projects are developing analytical methods, databases, and decision-support tools aimed at improving sustainability outcomes in offshore wind development. This section provides an overview of such tools based on a targeted mapping of recent and ongoing projects relevant to offshore wind planning and marine spatial decision-making.
Filter projects by related SUSTAINOW topic:
| Related SUSTAINOW topic | Project abbreviation (and link) | Year of completion | Purpose | Sustainability scope |
|---|---|---|---|---|
| Marine data | ILIAD | 2025 | To develop a data-intensive, cost-effective Digital Twin of the Ocean | Environment, social |
| Marine data | SEADITO | 2027 | Restore ocean health by socialecological analysis and models for digital twin ocean. | Social, environment |
| Marine data | AquaInfra | 2026 | Restore ocean health by developing a virtual environment with multidisciplinary data and services | Environment |
| Marine data, siting | DTWO | 2027 | Digital twin of offshore wind, siting conditions | Socio-economy |
| Siting | Spowind | 2026 | Overcoming challenges with a marine spatial planning WebGIS tool. Focus on Mediterranean Sea | Social, socio-economy, Environment |
| Siting, Impacts | WIMBY | 2025 | Addressing restrictive regulations and negative public perception, providing a Web-GIS interactive platform | Environment, social |
| Tenders, Impacts | WindScore | 2028 | To develop a decision-making tool in the form of a 360-degree KPI toolbox. Design of tender criteria and holistic evaluation | Environment, social, socio-economy |
| Impacts | GES4SEAS | 2026 | Achieving good environmental status for maintaining ecosystem services, methods for assessing integrated impacts of cumulative pressures. | Environment |
| Impacts | ActNOW | 2027 | Advancing understanding of cumulative impacts on European marine biodiversity, ecosystem functions and services for human wellbeing. Method developed. | Environment |
| Impacts | Off-coustics | 2028 | Reducing offshore wind and tidal turbine damage with focus on acoustic repercussions. Model developed. | Environment |
| Impacts, Floating | FloatFARM | 2027 | Offshore wind, reducing negative impacts on marine life and enhancing acceptability. Method developed. | Environment, social |
| Impacts, Floating | FLOATANT | 2022 | Deep water floating wind, exploring environmental and social impact of floating platform. Method developed. | Environment, social |
| Impacts, Floating | ATLANTIC | 2029 | Technological advancement of floating offshore wind turbines. Method development. | Environment |
| Impacts, Floating | CoreWind | 2023 | Research on concrete-based floating substructure concepts. LCA work. | (LCA) |
| Impacts | ROMEO | 2022 | Solutions for reducing Operation & Maintenance (O&M) costs, LCoE reductions method | Socio-economy |
| Impacts | UNITED | 2023 | Multi-use platforms or co-location of different activities in a marine and ocean space. Method developed. | Environment, socio-economy |
| Impacts | MARINEWind | 2025 | Provide an interactive tool to assess the Levelised Cost of Energy for offshore wind technologies. | Socio-economy |
| Mitigation, Impacts | EcoCorp | 2025 | Integration of biodiversity in offshore wind planning by combining ecosystem and corporate approaches. | Environment |
| Mitigation, Floating | INF4INiTY | 2027 | Nature inclusive designs for subsea components of floating offshore wind installations. | Environment |
| Mitigation | OCEaN | - | Achieving a nature-friendly energy transition, catalogue of mitigation measures | Environment |
| Acceptance | WENDY | 2025 | Unravelling the factors triggering social acceptance of wind farms – technical, environmental and social | Environment, social |
6 Key findings and identified gaps
The combined analysis across life-cycle phases, tools, and sustainability scope highlights several key findings:
- Strong institutionalisation of mitigation, supported by mandatory regulatory frameworks.
- Regulatory requirements for key assessment tools ensure attention to a system perspective on OWF.
- Limited and uneven integration of enhancement, with no consistent requirements across tools.
- Fragmentation between regulatory and voluntary tools, limiting integrated decision support.
- Variability in the treatment of cumulative, transboundary, and lifecycle impacts.
- Limited coverage of later life-cycle phases, particularly repowering and decommissioning.
These findings indicate that current assessment practice is well-developed in terms of impact identification and mitigation, but less effective in supporting proactive and systemic sustainability outcomes.
Basis for further work
The results of this report provide a structured basis for subsequent project activities, particularly in relation to:
- Identifying priority areas for improving decision support.
- Developing approaches that better integrate enhancement alongside mitigation.
- Strengthening the use of lifecycle and system-oriented assessments.
- Improving the integration of tools across life-cycle phases and decision levels.
The overall life-cycle framework provides a useful and conceptually clear picture for understanding OW development processes. However, in practice, planning and permitting processes are often iterative and overlapping rather than strictly sequential. Permitting, environmental assessment, technical optimisation, and stakeholder negotiations may evolve in parallel and continue across multiple phases. Acknowledging this complexity strengthens the practical applicability of the framework and highlights the need for flexible and adaptive assessment approaches.
Overall, the analysis in the report points to the need for a transition from a predominantly impact mitigation framework towards a more balanced approach, where assessment tools also support the identification and realisation of positive sustainability outcomes.
