What is the Carbon Intensity Indicator?
The Carbon Intensity Indicator (CII) measures the energy efficiency of a ship based on the amount of CO₂ emissions per cargo carried and per nautical mile. The indicator is expressed in grams of CO₂ per deadweight-nautical mile (gCO₂/DWT-nm). CII is an important part of the decarbonization strategy of the International Maritime Organization (IMO).
Since 2024, ships receive an annual CII rating from A to E, based on their verified operational performance. This means:
- A – very good performance
- B – good performance
- C – average performance
- D – below-average performance
- E – insufficient performance
The performance thresholds are gradually tightened until 2030, requiring ships to continuously improve their operational efficiency. Normec Verifavia provides accredited CII verification so that shipowners and operators can demonstrate that their reporting complies with IMO regulations.
Which ships are subject to CII regulations?
The CII regulation is laid down in MEPC.328(76), adopted during MEPC 76 in June 2021, and incorporated into MARPOL Annex VI.
The regulation introduces new requirements for:
- Operational Carbon Intensity Indicator (CII) and CII rating
- Enhanced Ship Energy Efficiency Management Plan (SEEMP)
CII applies to:
- Cargo ships and cruise ships of 5,000 GT and above
These are the same ships that fall under the IMO Data Collection System (IMO DCS).
What does CII mean for shipping operators?
Ships must collect and report additional fuel and operational data annually.
This data includes, among other things:
- Fuel consumption per type of consumer and fuel type
- Fuel consumption when the ship is not underway
- Use of shore power
- Laden distance travelled
- Installation of innovative technologies
- Total transport work
This data is reviewed by a recognized verifier, who then calculates the attained CII. Based on the attained and required CII, the ship receives a CII rating from A to E.
How Normec Verifavia supports you
Normec Verifavia helps shipping companies verify CII data and reports according to international regulations.
Our services:
- Accredited and independent verification
Normec Verifavia is recognized under ISO 14065 and performs verifications for, among others, EU ETS, MRV, CII and FuelEU Maritime. - Experience and proven track record
We have carried out more than 1,200 CII verifications, including more than 500 through integrated digital platforms. - Digital integration
Our systems are integrated with more than 20 IT platforms, including Stormgeo and DANOS, for accurate and efficient reporting. - Efficient and reliable processes
Our structured verification processes ensure timely completion and reduced administrative burden. - Collaboration with flag states and classification societies
We work with flag states such as Antigua & Barbuda, St. Kitts & Nevis and Dominica, as well as classification societies such as RINA and KR. - Independent expertise
Our marine experts have many years of operational experience in the shipping sector. - Customer trust
More than 200 shipping operators rely on our verification services.
What does this deliver for you in practice?
- You comply with IMO obligations for emissions reporting
- You gain insight into the operational efficiency of your ships
- You can take timely action to avoid a low CII rating
- You strengthen your sustainability position towards stakeholders
- You reduce compliance risks under future regulations
Improvement plans and future requirements
The required CII is calculated based on a reference year (2019) and an annual reduction factor. This means that ships must operate more efficiently every year to maintain the same rating.
When a ship:
- Receives a rating D for three consecutive years, or
- Receives a rating E for one year
the operator must submit an improvement plan.
This plan describes measures to improve the ship’s energy efficiency to at least rating C. The calculation methodology for CII also includes correction factors for specific routes and circumstances, as laid down in:
MEPC.355(78) – Interim guidelines on correction factors and voyage adjustments for CII calculations (CII Guidelines G5).
The verification process for CII
-
1.
Submission
Shipping companies submit their IMO DCS fuel oil consumption reports and the calculated CII value to Normec Verifavia.
-
2.
Verification
We review the accuracy of the submitted data, including fuel consumption, distance travelled and CII calculations.
-
3.
Recommendation
After successful verification, we send a formal recommendation to the relevant flag state authority.
-
4.
Issuance of Statement of Compliance (SoC)
Based on the verification and recommendation, the flag state issues a Statement of Compliance.
Would you like to know more about the Carbon Intensity Indicator?
Downloads
- Resolution MEPC.348(78) – 2022 Guidelines for administration verification of ship fuel oil consumption data and operational carbon intensity
- MEPC.352(78) – 2022 Guidelines on operational carbon intensity indicators and the calculation methods (CII Guidelines, G1)
- MEPC.354(78) – 2022 Guidelines on the operational carbon intensity rating of ships (CII rating Guidelines, G4)
- MEPC.349(78) – 2022 Guidelines for the development and management of the IMO ship fuel oil consumption database
- MEPC.353(78) – 2022 Guidelines on the reference lines for use with operational carbon intensity indicators (CII reference lines Guidelines, G2)
- MEPC.355(78) – 2022 interim Guidelines on correction factors and voyage adjustments for CII calculations (CII Guidelines, G5)
Frequently asked questions about the Carbon Intensity Indicator
-
When a ship receives a CII classification D for three consecutive years or a classification E for one year, a corrective action plan must be included in SEEMP Part III (SEEMP III) and implemented.
This plan describes measures to improve the ship's energy efficiency to at least classification C. In such cases, SEEMP III approval must be obtained before the ship can receive a Statement of Conformity (SoC).
-
The carbon intensity indicator (CII) can be calculated by several methods. Two examples are:
- Annual Efficiency Ratio (AER) - calculated as emissions per mile deadweight-ton and applied to ships where the weight of the cargo is the main factor.
- Capacity Gross Ton Distance (cgDist) - calculated as emissions per gross ton-mile and used for ships where cargo volume plays a larger role.
-
The first annual CII rating was awarded in 2024, based on verified operating data for calendar year 2023.
-
When a ship is transferred to another shipping company, the previous operator must have the partial emissions data for the operating period verified by the competent authority or an authorized organization.
The verified data and associated documentation must then be transferred to the new operator within one month from the date of transfer.
-
Boil-off gas (BoG) used as fuel can come from either the cargo or the heel of the ship.
When calculating LNG fuel consumption, the mass of nitrogen must be subtracted because nitrogen does not produce CO₂. This is done based on:
- CTMS certificates, or
- Real-time gas chromatograph measurements.
Relevant certificates and reports should be submitted for verification of annual fuel consumption and CII calculation.
-
The annual reduction factors for operational carbon intensity were established in IMO Resolution MEPC.400(83), as part of the guidelines for CII reduction factors (G3).
Year
Reduction factor relative to 2019
2023 || 5%
2024 || 7%
2025 || 9%
2026 || 11%
2027 || 13.625%
2028 || 16.250%
2029 || 18.875%
2030 || 21.500%
These reduction factors mean that ships must operate more efficiently each year to maintain the same CII rating.