EEXI: the one-time design test
The Energy Efficiency Existing Ship Index asks whether an existing ship's design efficiency matches what would be required of a comparable newbuild. It applies, in general terms, to each ship of 400 gross tonnage and above in the ship types MARPOL Annex VI covers. Each ship's attained EEXI, calculated from its technical characteristics, must not exceed the required value for its type and size. The amendments entered into force on 1 November 2022. Compliance had to be demonstrated at the first annual, intermediate or renewal IAPP survey on or after 1 January 2023. For most of the fleet, compliance was achieved through engine power limitation or shaft power limitation, capping usable power with an override reserved for safety. The calculation is supported by an approved EEXI Technical File, and the International Energy Efficiency Certificate is reissued. Many older ships never had an EEDI calculated, because the design index only applied to newbuildings from 2013. For those ships the guidelines allow the reference speed to be approximated from statistical parameters for the ship type and size, under paragraph 2.2.3.6 of resolution MEPC.350(78), rather than derived from ship specific sea trial data. It is the pragmatic path for a fleet whose original design documentation is thin or missing. EEXI was a gate, not a journey. Once demonstrated it is done, unless the ship is modified. Its practical legacy is a fleet that is, on paper and in fuel curves, slightly slower and meaningfully more efficient at its new operating point.
CII: the rating that never stops
The Carbon Intensity Indicator measures operational efficiency: CO2 emitted per deadweight tonne mile, or per gross tonne mile for some ship types. It is calculated annually from the fuel consumption data ships already report under the IMO Data Collection System. Each ship of 5,000 gross tonnage and above receives a rating from A to E against a required value that ratchets down against a 2019 reference line. The reduction factor is 11 per cent for 2026. Resolution MEPC.400(83), adopted on 11 April 2025, replaced Table 1 of the G3 Guidelines and set the remaining steps: 13.625 per cent for 2027, 16.25 per cent for 2028, 18.875 per cent for 2029 and 21.5 per cent for 2030. The enforcement mechanism is corrective rather than punitive. A ship rated D for three consecutive years, or E in a single year, must develop a plan of corrective actions in SEEMP Part III and submit the revised SEEMP for verification, in no case later than one month after reporting the attained CII. No trading prohibition attaches to the rating itself. The sharper consequences are commercial. Ratings are visible to charterers, financiers and cargo interests, and a weak letter is increasingly a negotiating disadvantage.
The mechanics that decide your letter
Because CII is annual and formulaic, details move ratings. Correction factors and voyage adjustments exist for defined situations, including ice class ships, shuttle tankers and certain cargo heating and port scenarios. Applying them correctly is free rating improvement, and failing to apply them is a self inflicted downgrade. Data quality is now worth money. The same fuel figures feed CII, EU Emissions Trading System liability and FuelEU Maritime accounting at the same time. An error propagates across three regimes and lands in three different places. Operationally the levers are familiar: speed and voyage optimisation, hull and propeller condition, weather routing and port time. CII turned them from cost savings into rating strategy. Charterparty clauses now allocate who controls those levers and who bears the consequences of them.
Where the regime goes next
The IMO's review of the CII framework continues. MEPC 83 agreed a work plan for Phase 2 of the CII review, running from spring 2026 to spring 2028, which will consider enhanced efficiency frameworks, additional metrics and alignment with the net zero strategy. The mid term Net-Zero Framework, with its fuel intensity standard and pricing mechanism, sits behind that and remains unadopted. It was approved at MEPC 83 in April 2025, adjourned at the second extraordinary session in October 2025, and not adopted at MEPC 84 in April 2026. MEPC 85 runs from 30 November to 3 December 2026, and the adjourned second extraordinary session is set to resume on 4 December 2026, subject to confirmation by MEPC 85. That resumed session, not MEPC 85, is the adoption decision point. That position is stated as at August 2026. The direction is one way. Operational carbon performance keeps gaining regulatory and commercial weight. Fleets that build honest measurement and routine optimisation now are buying themselves room under every version of the rules that follows.