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

Ship Energy Efficiency Management Plan (SEEMP) / Energy Efficiency Operational Indicator (EEOI)


The date of development and originator of the Ship Energy Efficiency Management Plan (SEEMP) that is present on the ship has been submitted; the plan has been developed in accordance with the Guidelines of IMO’s MEPC.1/Circ.683. and the 10 sub-points fixed bonus are added. Alternatively, ships may chose 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). Supply of data on the type of cargo and/or the value of the EEOI is not required but may be considered.

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.

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