Theoretical Technical Efficiency Indexes

EIV and EEDI

Two different measures characterize the technical efficiency of ships. They are both measured in gCO₂/ton/nautical mile. They are theoretical measures: they really on applying formulas based on the characteristics of a ship, not on experimental measures.

EIV: Efficiency Indicator Values
EEDI: Energy Efficiency Design Index

Ships are invited to report a technical efficiency using one of these two indexes.

In the GreenFerries scope of passenger ferries:

255 ships have declared EIV values
only 8 ships have reported using EEDI values
17 ships have not reported any of the two

Correlation between EIV and EcoScore

We tried looking for correlation between the theoretical technical efficiency and the EcoScore. The EcoScore is defined based on the reported annual average gCO₂/km/person. Considering the vast majority of ferries are reporting with the EIV value, we have chosen to ignore the EEDI values.

Here is a scatter plot of the EIV and this average gCO₂/km/person:

Scatter plot EIV per average emissions reported per distance per person

both axes are truncated to ignore outliers

Conclusion from observation: there does not seem to be any meaningful correlation between the two values.