EEXI, a design measure
EEXI is a one-time, technical index that applies the energy-efficiency thinking of the newbuilding EEDI to existing ships. A ship must demonstrate an attained EEXI at or below a required value, often achieved through measures such as engine power limitation, and the result is documented and verified.
CII, an operational rating
CII rates a ship's actual operational carbon intensity each year, assigning a rating from A to E, with the required level tightening over time. A ship rated D for three consecutive years, or E in a single year, must submit a corrective action plan in its SEEMP. CII makes how you run the ship, speed, routing, maintenance, a compliance matter, not just a commercial one.
SEEMP and verification
The Ship Energy Efficiency Management Plan (SEEMP) ties it together, with Part III setting out how the ship will meet its CII targets. Data is collected, reported and verified, so the rating rests on auditable evidence, exactly where a compliance platform earns its keep.