What is EEXI?

The IMO is implementing short-term measures to improve ship energy efficiency and reduce fuel consumption to minimize carbon emissions from shipping.

Among these measures is the Energy Efficiency Existing Ship Index (EEXI), which comes into effect on January 1, 2023. The EEXI is a framework for assessing the energy efficiency of in-service vessels as designed and built. To determine this, the EEXI accounts for a vessel’s engine and auxiliary engine power, transport capacity and given reference speed. Emissions are calculated using the installed power of the main and auxiliary engines, the engine’s specific fuel oil consumption and a conversion factor of the fuel’s mass into CO2 mass.

All EEXI calculations must be conducted in accordance with MARPOL Annex VI. Calculation requirements for the EEXI are based on those used for the Energy Efficiency Design Index (EEDI).

Tell me more about EEXI calculations

Existing ships will be required to assess their energy efficiency index, known as “attained EEXI”. All ships must individually calculate and receive approval of attained EEXI by their first annual, intermediate or renewal International Air Pollution Prevention (IAPP) survey of 2023. Attained EEXI will then be compared with required EEXI, a performance level set by the IMO regulations. Required EEXI values are determined based on fleet statistics per ship type, cargo capacity, and propulsion method.

Formula of EEXI


How do I achieve EEXI compliance?

Vessels’ attained EEXI and related technical files will need to be verified during their annual, intermediate or renewal IAPP survey following January 1, 2023. Compliant ships will be issued an International Energy Efficiency Certificate (IEEC).

Non-compliant ships will need to find ways to comply with the required EEXI values. Technical changes such as Engine Power Limitation (EPL) and Shaft Power Limitation (SHaPoLi) can reduce the calculated emissions. Ships with particularly poor EEXI performance may require retrofitting, energy-saving devices, propeller modifications or green solutions like wind-assisted propulsion.

EEXI Timeline 2022-2024

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Sebastien Crouzet

International Statutory Affairs Manager

Bureau Veritas M&O

Few things set shipowners on edge quite like the phrase ‘required calculations’. When the EEXI was announced, Bureau Veritas immediately started developing a digital calculation tool. Designed with users in mind, VeriSTAR Green does the heavy-lifting, helping shipowners report on emissions, calculate EEXI and achieve regulatory compliance.

Bureau Veritas’ EEXI services

Bureau Veritas Marine & Offshore helps ship owners, operators and managers to perform EEXI assessments and gain approval for their preliminary technical files. We support shipowners in identifying the technical measures needed to improve their vessels’ energy efficiency and limit emissions. Further, our experts ensure that ships meeting EEXI requirements receive the requisite IEEC.

Our services are complemented by VeriSTAR Green, a web platform designed to make EEXI easier, helping users easily and efficiently perform EEXI calculations. Shipowners can calculate both attained and required EEXI values, comparing the two and measuring their fleets’ environmental impact. VeriSTAR Green also gives users digital access to Bureau Veritas experts who can verify their emissions calculations. Furthermore, they can reach technical advisory services to improve performance from independent experts from BV Solutions M&O.


  • What is the difference between EEXI and EEDI?

    The EEDI is a design index applicable to newbuilds, while the EEXI applies to existing vessels. Both the EEDI and EEXI use the same calculation method to report on ship energy efficiency. Approximately 70% of EEDI-compliant ships are expected to achieve EEXI compliance without alteration.

  • Which ships does EEXI apply to?

    EEXI provisions apply to all ships of 400 GT or more that are categorized in the MARPOL Annex VI regulations listed below and are subject to MARPOL Annex VI chapter 4. As required EEXI values are determined by ship type, operators will need to assess ship energy efficiency against vessel type requirements.

    MARPOL Annex VI regulation

    Ship type


    Bulk carrier


    Combination carrier




    Cruise passenger ship


    Gas carrier


    General cargo ship


    LNG carrier


    Refrigerated cargo carrier


    Ro-ro cargo ship


    Ro-ro cargo ship (vehicle carrier)


    Ro-ro passenger ship



  • What is VREF in EEXI?

    A required element in calculating EEXI is a vessel’s reference speed (VREF) at a certain draft. EEXI calculation guidelines enable shipowners to determine VREF using an approximate formula for their ship type and installed power. Shipowners can also use more precise methods, such as sea trials, towing tank tests or computational fluid dynamics assessments.

  • Is EEXI evaluated annually?

    Existing ships are only required to gain EEXI approval once over the course of their in-service lifetime. Only in the case of extensive retrofitting, modifications, or conversion will EEXI need to be reevaluated and reapproved.

  • How can I improve my vessel to achieve EEXI compliance?

    Shipowners can turn to EPL or SHaPoLi as short-term solutions for reducing emissions. Owners can also make permanent modifications to engines, such as cutting out turbo chargers, or install energy-saving devices like wake-equalizing ducts, bulbous bows or propeller fins.

  • Is EEXI compliance going to be expensive?

    The majority of vessels will face limited CAPEX to meet EEXI requirements, as most ships will not undergo modification. EEXI may affect OPEX for some vessels, as crew undertake additional training and ships make speed adjustments. However, for ships undergoing retrofitting to achieve compliance, CAPEX may be significant. Shipowners will evaluate and decide on a case-by-case basis which are their most cost-effective options.

Find out more about EEXI