Eedi and eeoi

Answer

Both EEDI and EEOI are energy efficiency metrics introduced by the IMO to reduce greenhouse gas emissions from ships, but they apply to entirely different stages of a vessel's lifecycle.

Energy Efficiency Design Index (EEDI)

• What it is: A static, design-phase index that estimates the theoretical CO₂ emissions of a ship per unit of transport work before it is built. It is an engineering baseline.

• Application: Mandatory for new ships (built on or after 1 January 2013) of 400 gross tonnage and above. The index forces ship designers to improve hydrodynamic hulls, optimize propulsion systems, and utilize energy-saving technologies to beat an IMO-mandated baseline that tightens over time (Phases 0, 1, 2, and 3).

• Simplified Concept:

Energy Efficiency Operational Indicator (EEOI)

• What it is: A dynamic, operational monitoring tool that measures the actual efficiency of a ship in service over a specific period or voyage. It reflects real-world variables like weather, hull fouling, main engine load, and actual cargo payload carried.

• Application: Used as a key monitoring mechanism within SEEMP Part I (Ship Energy Efficiency Management Plan) for existing vessels to track the operational success of efficiency measures over time.

Core Differences at a Glance