A ship’s attained EEXI indicates its energy efficiency compared to a baseline. Ships attained EEXI will then be compared to a required Energy Efficiency Existing Ship Index based on an applicable reduction factor expressed as a percentage relative to the Energy Efficiency Design Index (EEDI) baseline. It must be calculated for ships of 400 gt and above, in accordance with the different values set for ship types and size categories. The calculated attained EEXI value for each individual ship must be below the required EEXI, to ensure the ship meets a minimum energy efficiency standard.
The CII determines the annual reduction factor needed to ensure continuous improvement of a ship’s operational carbon intensity within a specific rating level. The actual annual operational CII achieved must be documented and verified against the required annual operational CII. This enables the operational carbon intensity rating to be determined.
How do the new ratings work?
Based on a ship’s CII, its carbon intensity will be rated A, B, C, D or E (where A is the best). The rating indicates a major superior, minor superior, moderate, minor inferior, or inferior performance level. The performance level will be recorded in a “Statement of Compliance” to be further elaborated in the ship’s Ship Energy Efficiency Management Plan (SEEMP).
A ship rated D for three consecutive years, or E for one year, will have to submit a corrective action plan to show how the required index of C or above will be achieved. Administrations, port authorities and other stakeholders as appropriate, are encouraged to provide incentives to ships rated as A or B.
A ship can run on a low-carbon fuel clearly to get a higher rating than one running on fossil fuel, but there are many things a ship can do to improve its rating, for instance through measures, such as:
- hull cleaning to reduce drag;
- Speed and routeing optimization;
- installation of low energy light bulbs; and
- installation of solar/wind auxiliary power for accommodation services.
EEXI overview and implementation
The Energy Efficiency existing ship Index (EEXI) is a measure introduced by the IMO to reduce the greenhouse gas emissions of ships. The EEXI is a measure related to the technical design of a ship. Ships have to attain EEXI approval once in a lifetime, by the first periodical survey in 2023 at the latest.
The required EEXI value is determined by the ship type, the ship’s capacity and principle of propulsion and is the maximum acceptable attained EEXI value.
The attained EEXI must be calculated for the individual ship, which falls under the regulation. Considering the different scenarios, it is important that you check the applicable scenario for your individual ship.
Class compliance
Depending on the technical solution, if changes are performed in the vessel’s structure or on any important components or systems on board, documentation shall be submitted for approval. This can be done through the alteration portal.
After approval of the documentation and installation/changes on board, a survey can be booked, and the changes will be verified by a surveyor.
Final implementation
Verification that the ship’s attained EEXI and technical file is in accordance with the requirements shall take place at the first annual, intermediate or renewal survey after 1st January 2023. The survey is part of the scope of the IAPP survey, and compliance is documented by issuance of the IEE certificate.
The EEXI measures CO2 emissions per transport work, purely considering the ship’s design parameters. EEXI does not require any measurement or reporting of true CO2 emissions while the ship is in operation. EEXI is the sister to EEDI, Energy Efficiency Design Index, which has been in force since 2013. These indexes measure the same in practice; however, EEDI is applied to new ships while EEXI applies to existing vessels. EEXI regulation is one of the most significant measures by the IMO to promote more environmentally friendly technologies and reduce the shipping industry’s carbon footprint.
Simplified, EEXI estimates CO2 emissions per transport work (grams of CO2 per ton-mile), although the equation is more complex, accounting for possible reduction factors, energy-saving equipment, etc.
The CII (Carbon Intensity Indicator) measures how efficiently a vessel above 5,000 GT transports goods or passengers and is given in grams of CO2 emitted per cargo-carrying capacity and nautical mile.
The first reporting of the CII based on 2023 data is due no later than 31 March 2024. Vessels will receive a rating of A (major superior), B (minor superior), C (moderate), D (minor inferior) or E (inferior performance level). The rating thresholds will become increasingly stringent towards 2030. A vessel rated D for three consecutive years or rated as E, will need to develop a plan of corrective actions.
Connection between the CII, DCS and SEEMP Part III
From 2024, at the latest by 31 March, the CII must be calculated and reported to the DCS verifier together with the aggregated DCS data for the previous year, including any correction factors and voyage adjustments.
In case of a D rating for three consecutive years or one E rating, the SEEMP Part III must be updated with a corrective action plan and verified before the SoC can be issued. The deadline for the SoC issuance remains the same (31 May). The corrective action plan should consist of an analysis of why the required CII was not achieved and include a revised implementation plan.
The intention of the enhanced SEEMP is to ensure continuous improvement, and its implementation will be subject to company audits.
Calculation of the CII
The CII unit is “grams of CO2 emitted per cargo-carrying capacity and nautical mile”, whereby cargo capacity is either deadweight or gross tons depending on ship type. In addition, to cater for special design and operational circumstances, the correction factors and voyage adjustments can be applied to the basic CII calculations for the purposes of determining the rating.
EEDI EEOI
Energy Efficiency Design Index (EEDI):
It is an index quantifying the amount of carbon dioxide that a ship emits in relation to the goods transported.
- indication of energy efficiency by CO2 emission (g) per cargo carry (ton mile) Theactual EEDI of a vessel is called the “attained EEDI” and is calculated based on guidelines published by IMO. The result must be below the limit “required EEDI” prescribed in MARPOL.
- For existing vessels, the EEDI is in most cases irrelevant. It will become relevant only if a ship undergoes a major conversion that is so extensive that the ship is regarded by the Administration as a newly constructed ship.
- For new ships, a technical file must be created showing the attained EEDI and its calculation process.
- The EEDI and the technical file will be subject to verification by the flag administration.
(New ship means a ship:
.1 for which the building contract is placed on or after 1 January 2013; or
.2 in the absence of a building contract, the keel of which is laid or which is at a similar stage of construction on or after 1 July 2013; or
.3 the delivery of which is on or after 1 July 2015.)
Energy Efficiency Operational Indicator (EEOI):
- An efficiency indicator for all ships (new and existing) obtained from fuel consumption, voyage (miles) and cargo data (tonnes)
- In its most simple form, the Energy Efficiency Operational Indicator is defined as the ratio of mass of CO2 (M) emitted per unit of transport work In order to establish the EEOI, the following main steps will generally be needed:
- define the period for which the EEOI is calculated
- define data sources for data collection;
- collect data;
- convert data to appropriate format; and calculate EEOI.
EEDI Technical File:
The EEDI Technical File is the basic document for the EEDI certification and includes all EEDI relevant data and information and EEDI calculation.
Part A
- General information of a ship
- Principal particulars
- Main engine(s) particulars
- Auxiliary engine(s) particulars
- Particulars of shaft generator
- Particulars of shaft motors (PTI)
- Particulars innovative electrical auxiliary systems
- Particulars of innovative technologies reducing main engine power for propulsion
- Model test information
- Reference speed
Part B
- EEDI Calculation &
- Correction factors details