The Environmental Ship Index (ESI) has helped shipping companies benefit from environmental port fee incentives for several years. Now, with ESI Core entering into force on 1 January 2027, the framework is evolving to better reflect today’s shipping realities while making participation simpler and more practical for shipping companies.
The updated methodology aligns more closely with current operational practices, creates additional opportunities to improve vessel scores, and simplifies reporting requirements by using data already available through existing compliance processes.
Why ESI Core Was Updated
Shipping and environmental regulation have evolved significantly in recent years. The updated ESI Core methodology modernizes the long-established ESI framework to better reflect operational reality and today’s environmental practices.
This includes,
Operational measures:
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cleaner fuel strategies
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shore power usage
Innovation:
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wind-assisted propulsion
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air lubrication
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batteries and emerging technologies
The updated framework creates more opportunities for vessels to improve their environmental score through measures that were previously not fully recognized within ESI.
More Operational Measures Are Recognized
Compared to the existing ESI Air methodology, ESI Core introduces a stronger focus on operational and performance-based environmental assessment. The methodology better reflects how vessels actually operate and how environmental performance is achieved in practice.
Operational measures such as shore power usage and cleaner fuel strategies can now contribute more directly to vessel scoring, alongside innovative emission reduction technologies. This creates clearer recognition for operational environmental performance and allows shipping companies to benefit more directly from measures already being implemented across fleets today.
Reporting Requirements Become Simpler
At the same time, ESI Core substantially simplifies reporting requirements and reduces overall administrative effort. The updated framework is designed around data that shipping companies already manage today, including:
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BDNs
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EDNs
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engine-related data
Reporting is also aligned more closely with existing IMO DCS timelines and annual reporting cycles. This helps simplify participation and allows companies to reuse existing datasets and reporting workflows instead of creating additional parallel processes.
What Shipping Companies Need to Do
The first ESI Core scores will be based on 2025 full-year vessel data. To ensure vessels are correctly assessed under the updated framework, all relevant 2025 data must be complete and correctly reflected in the new ESI Core structure. Importantly, existing entries under ESI Air — for example SOx or BDN data — are not automatically sufficient under ESI Core. The relevant data must be available and correctly reflected in the new subscore tabs within the updated structure. Shipping companies are therefore encouraged to review and update their vessel data as early as possible to ensure a smooth transition to ESI Core.
Why This Matters
If vessel data is incomplete or outdated:
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ESI Core scores may not be calculated correctly
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vessels may not qualify for port incentives
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commercial benefits linked to ESI participation may be lost
As environmental incentives continue to play an increasingly important role across ports globally, ensuring correct participation under ESI Core becomes commercially relevant for shipping companies.
Key Timeline for ESI Core
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ESI Core enters into force: 1 January 2027
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First scores based on: 2025 full-year data
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Validity of first scores: January – June 2027
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From July 2027: yearly update cycle based on 2026 data
Shipping companies are requested to update 2025 full-year data for all vessels in their fleet by 31 July 2026.
ESI Core as the Next Step for Environmental Incentives
ESI Core is not a fundamental reinvention of ESI. It is the next logical evolution of the scheme.
The updated methodology reflects the realities of modern shipping and regulation more accurately, creates more opportunities to benefit from environmental incentives, and keeps participation straightforward, practical and cost-efficient.
For shipping companies, ESI Core strengthens the connection between operational environmental performance and commercial incentive opportunities while reducing the administrative complexity traditionally associated with reporting frameworks.
If you have any questions or need support, please contact the ESI Administration.
