Answer
The Energy Efficiency Design Index (EEDI) is a mandatory technical mechanism under MARPOL Annex VI aimed at driving down greenhouse gas emissions by making new ship designs progressively more energy-efficient.
What is the Required EEDI Line Called?
The Required EEDI represents the maximum allowable $\text{CO}_2$ emissions per capacity-mile for a newly built ship. To achieve compliance, a new vessel's Attained EEDI must be less than or equal to the Required EED
How is the Required EEDI Line Drawn?
Data Collection Baseline: The IMO collected empirical design data (power, deadweight, speed) from thousands of existing ships built between 1999 and 2009 to establish a representative baseline of performance for each specific ship type (e.g., tankers, bulkers, gas carriers).
Formulating the Reference Curve: Using this historical data, a statistical regression analysis was performed to plot a curve using the baseline formula:
| Symbol | Meaning |
|---|---|
| a | Constant depending on ship type |
| b | Ship capacity, usually 100% DWT |
| c | Constant depending on ship type |
3. The Required EEDI line is drawn by reducing the reference line by a percentage called the reduction factor X.
IMO states that the attained EEDI must be less than or equal to the required EEDI, and the required EEDI is calculated using the reduction factor compared with the reference line.