Energy Efficiency Existing Ship IndexEEXI
A one-time IMO design-efficiency standard that existing ships must meet, the in-service counterpart of the EEDI for new ships.
The Energy Efficiency Existing Ship Index (EEXI) is a technical, design-based measure of a ship’s CO₂ efficiency that existing vessels must satisfy from 2023. It is calculated like the Energy Efficiency Design Index (EEDI) for newbuildings and compared against a required value for the ship type and size.
Unlike CII, which is operational and assessed yearly, EEXI is a one-off certification of the ship’s design potential. Many owners meet it by limiting engine power, which also encourages slower steaming.
On The Maritime
Also known as: EEXI, energy efficiency existing ship index.
Related terms
Carbon Intensity IndicatorCII
An IMO operational measure of how much CO₂ a ship emits per unit of transport work, graded A–E each year.
Energy Efficiency Design IndexEEDI
An IMO design standard that caps the CO₂ emitted per unit of transport capacity for newly built ships.
International Maritime OrganizationIMO
The United Nations agency that sets global rules for ship safety, security and pollution prevention.
Slow Steaming
Deliberately sailing below design speed to cut fuel consumption, emissions and effective fleet supply.
Plain-English reference definition — our own explanation of a standard shipping concept, not a licensed source or legal advice. See the full glossary or the broader maritime dictionary.
Last reviewed: June 2026.