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Framework for Assessing Ecological and Cumulative Effects (KEC)

The Framework for Assessing Ecological and Cumulative Effects (KEC) is an instrument for calculating the possible effects of existing and future offshore wind farms on the populations of protected species and their habitat. This concerns the ecological effects of the already built and planned wind farms together in the period up to and including 2033 (Roadmap 21 gigawatts). The site decisions for the various wind farms also look at whether site-specific effects can be expected. That also involves determining which mitigation measures can be taken to prevent any significant negative effects. These are effects that would cause a structural decline in the populations of species to be protected and would affect the natural resilience of the species. By identifying the ecological effects of a future wind farm scenario at an early stage, the risks surrounding the roll-out of such a scenario are identified in good time and action can be taken to manage risks.

Continuous refinement of knowledge and assumptions

The KEC is continuously refined and supplemented with the latest insights. There is a new version approximately every two years. In addition to the most recent insights from new research, each new version also includes calculations of the cumulative effects of a new wind farm scenario. Assumptions that were made earlier are continually refined by new insights. The most recent version of the KEC, KEC 5.0, dates from April 2025.

KEC documents and publications

The Framework for Assessing Ecological and Cumulative effects 5.0 (2024-2025) consists of

Part A:

To be published soon.

Parts B:

• KEC 5.0. Report Part B Marine Mammals, Heinis et al, 2025; (pdf, 8.8 MB)
• Collision effects of North Sea wind turbines on bird species within the ‘Kader Ecologie & Cumulatie (KEC)’ 5.0. Actualisation of models, data and predicted mortality for Dutch offshore wind development scenarios. (pdf, 3.4 MB)
• Population level effects of displacement of marine birds due to offshore wind energy developments, KEC 5. (pdf, 5.1 MB)
• Impact of offshore wind farms on the North Sea ecosystem. Scenario study for the partial revision of the Dutch offshore wind planning. (pdf, 12 MB)
• New approach to quantitatively estimate bat casualties at offshore wind farms (pdf, 714 kB)
• Marine Strategy Framework Directive descriptors in relation to OWFs and Framework for Assessing Ecological and Cumulative Effects (KEC 5.0). (pdf, 751 kB)

Background documents:

• Letter report Seals. (pdf, 2.5 MB)
• Letter report Resident cetacean species in the North Sea. (pdf, 582 kB)
• Letter report Changes in Harbour porpoise distribution in the North Sea. (pdf, 593 kB)
• Knowledge update KEC5 density maps seabirds. (pdf, 636 kB)

ALI-thresholds

Memo ALI dempelwaardes (pdf, 136 kB) (in Dutch)

The Framework for Assessing Ecological and Cumulative effects 4.0 (2021 - 2022) consists of:

Part A reports:

Part  B reports:

The Framework for Assessing Ecological and Cumulative effects 3.0 (2018 - 2019) consists of:

Part A

Part B reports

Part C: Summary

Framework for Assessing Ecological and Cumulative Effects 3.0: Beschrijving and assessment of the cumulative effects associated with the implementation of the 2030 Offshore Wind Energy Roadmap

Relationship between parts A, B and C

Part A of the KEC report provides the conceptual framework for the approach to ecology and accumulation, and describes its implementation for offshore wind energy. Part A replaces previously published versions. The substantive reports (in Part B) further elaborate the substantive methods and models used, and include the calculations for the roadmap as made with the models. New reports have been added to Part B.

Part C provides an executive summary of the substantive reports and states the conditions required for the implementation of the 2030 Roadmap. Part C is new by comparison with previous versions.

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