Energy Efficiency Operational Indicator (EEOI)
"A voluntary monitoring tool recommended by the IMO to measure the energy efficiency of a ship in operation, defined as the ratio of mass of CO2 emitted per unit of transport work."
Definition
The Energy Efficiency Operational Indicator (EEOI) is an operational index that allows shipowners to assess the CO2 efficiency of their ship over time. Unlike the EEDI (which is for design), EEOI measures real-world performance.
Formula
EEOI = (Total CO2 Emissions) / (Cargo Mass × Distance Sailed)
Usage
While EEOI is voluntary (unlike the mandatory CII), it is widely used for internal benchmarking. It helps fleet managers evaluate the effectiveness of operational changes, such as hull cleaning or weather routing, by providing a normalized efficiency score across different voyages.