EEDI vs. EEXI vs. EEOI Framework

Answer

1. EEDI (Energy Efficiency Design Index)

• Focus: Newbuilds.

• Purpose: To promote the use of more energy-efficient equipment and engines. It sets a minimum energy efficiency requirement for new ships based on their design.

• Core Concept: It is a "technical" measure. It represents the amount of CO₂ emitted per unit of transport work (g/t⋅nm) based on the ship's design parameters (engine power, speed, capacity).

• Status: Mandatory for new ships since 2013; progressively tightened through "Phases" (Phase 1, 2, 3, and now 4).

2. EEXI (Energy Efficiency Existing Ship In

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• Focus: Existing Ships.

• Purpose: To ensure that existing ships (built before EEDI requirements or before they became strict) meet a one-time technical efficiency standard.

• Core Concept: It is effectively the "EEDI for existing ships." If a vessel does not meet the required EEXI, it must undergo technical modifications, the most common being EPL (Engine Power Limitation) or Shaft Power Limitation (ShaPLim), effectively capping the maximum power output to reduce CO₂.

• Status: A one-time certification performed at the first periodical survey after 2023.

3. EEOI (Energy Efficiency Operational Indicator)

• Focus: Day-to-Day Operations.

• Purpose: A voluntary monitoring tool that allows shipowners and operators to measure the fuel efficiency of a ship in operation over a specific period.

• Core Concept: Unlike EEDI/EEXI, which are fixed design values, EEOI is a real-world measurement. It changes based on the weather, cargo volume, hull condition, and fuel type.

• Relation to CII: While EEOI is voluntary and provides a granular way to measure efficiency, CII (Carbon Intensity Indicator) is the mandatory regulatory framework that uses EEOI-style data to grade the ship annually (A to E).

Comparison Table: At-a-Glance