ESI Calculation Example

Below an example is provided of an ESI calculation for a specific ship. The ship in the example has one main engine and three auxiliary engines. The ship uses HFO and MDO/Gasoil. For the formulas and baselines see ‘ESI Formulas’ and ‘IMO annex Regulations and ESI Baselines’.


Nitrogen oxides


Main engine(s) Auxiliary engine(s)
NOX Limit Value 17 11.5 g/kWh
NOX Rating 15 11 g/kWh
Δ Emission 2 0.5
Rated Power 9480 970 kW
Number of engines 1 3

{(17 – 15) x 9480/17 + (11.5 – 11) x 970 x 3/11.5} x (1/9480 + 970 x 3) x 100 = 1241 x 0.008 = 10.0

Sulphur oxides


The average sulphur content of the different fuels is extracted from the bunker delivery notes. The average for the respective fuels is the weighted average over all bunkers.

HFO HFO LS / MDO/Gasoil MDO/Gasoil LS
Baseline 3.50 1.00 0.50 % S (m/m)
Actual 2.00 0.60 0.08 % S (m/m)

For the different fuels, the relative improvement compared to the baselines is calculated; see also ‘ESI formulas’ and ‘IMO annex regulations and ESI baselines’

(3.50 - 2.00) / (3.5 - 1.0) x 30 + (1.00 - 0.60) / (1.0 - 0.5) x 35 + (0.50 - 0.08) / (0.5 - 0.0) x 35
= 18.0 + 28.0 + 29.4 = 75.4


Energy Efficiency Operational Indicator (EEOI)


Ships may choose to report on two of the EEOI data sets viz. fuel consumption and distance sailed; the data provided should be as described in the definitions section of the Guidelines for Voluntary Use of the Ship Energy Efficiency Operational Indicator (MEPC.1/Circ.684). The reporting period for the two data sets should coincide with the reporting period for the BDNs of the ship. A 10 sub-points fixed bonus will be granted to vessels submitting these data.

Supply of data on the type of cargo and/or the value of the EEOI is not requested but may be considered; a section for inclusion of the EEOI value is provided in the Ship Owner section but its use and completion are optional. These data will only be stored and will not be used in the calculation of the ESI CO2 Score.

ESI Score


For this example the ESI sub- points are as follows leading to an ESI Score of 34.0 points:

(2 x 10.0 + 75.4 + 10.0) / 3.1 = 34.0

The presence on this ship of OPS would result in adding 35 OPS bonus points and the following ESI Score:

(2 x 10.0 + 75.4 + 10.0 + 35.0) / 3.1 = 45.3