and by comparing them, identify the most optimised 
designs, the ones candidate for implementation.  
For this problem, a number of KPIs may be 
selected to describe both the economic and 
environmental dimensions. In this example, we 
further assume that a decision maker selects as the 
most appropriate for the ship economy three KPIs, 
namely the CAPEX, OPEX to represent costs and 
AAB for the revenues. CAPEX measures, in thousand 
$, the funds that a ship owner uses to purchase a 
vessel from a shipyard, OPEX accounts in thousand $ 
per year, the ongoing costs that a ship owner pays to 
run the ship over a specific period, e.g. typical year of 
operation, while AAB represents the revenues and is 
the average annual benefits form the ship, measured 
in thousand $ per year. The details (formulas, data 
parameters) for the estimation of these KPIs are not 
mentioned here due to the limited size of the paper. 
Accordingly, the environmental savings are described 
by EEDI (Energy Efficiency Design Index) and the 
NOx and Sox emissions calculated from the technical 
specifications of each alternative design.  
The values of the above mentioned KPIs appear 
in Table 1. In this table, the first design, indicated as 
REF, corresponds to the basic ship reference that 
participates in the assessment equally with the rest of 
the alternative designs. 
Table 1: The basic data set.  
Desgin CAPEX  OPEX  AAB  EEDI  NOx  SOx 
REF 6582 1.454 5.836 6.8 13.81 3.45 
d1 5377.1 1.447 3.494 7.7 12.3 2.26 
d2 5751.8 1.507 3.613 3.6 11.46 1.25 
d3 5924.2 1.362 5.284 4.5 11.99 2.92 
d4 6914.8 1.61 3.856 4.2 11.14 1.96 
d5 5432.2 1.328 5.397  4 12.09 3.74 
d6 5754.8 1.567 4.728 3.9 14.37 1.98 
d7 5650.4  1.6  6.023 3.1 11.01 1.5 
d8 5524.8 1.362 3.863 2.9 12.9 2.21 
d9 6718.6 1.61  3.8  4 12.09 3.74 
d10 7180.9 1.328 3.893 4.4 11.39 1.81 
d11 5944.9 1.424 3.875 5.6 14.44 3.75 
d12 7056.5 1.575 4.388  4 12.09 3.74 
d13 5360.7 1.338 5.879 3.2 11.35 4.98 
d14 5412.5 1.297 4.691 6.8 13.99 2.48 
d15 6247.4 1.547 3.474 7.7 11.66 3.76 
d16 6526.3  1.61  5.157  4 12.09 3.74 
d17 5337.8 1.328 4.058 3.4 12.51 2.6 
d18 6260.3 1.435 5.165 7.9 11.03 4.43 
 
From inspecting the data in Table 1, we may 
notice that a number of alternatives (e.g. d2) have 
adequate performance on economy and poor in the 
environmental KPIs while for others (e.g. d14) is 
vice-versa. 
In order to estimate the values of the composite 
indicators ECO, ENV, models (1), (2) are applied to 
the data set. Before that, a normalization process (see 
Section 3.3) eliminates the differences in the scales of 
measurement and reverses to positive the values for 
the indicators with negative utility such as CAPEX, 
OPEX, NOx, SOx. In such an arrangement the two 
composite indicators ECO, ENV appear both with 
positive utility (the higher the values, the better is the 
design). Moreover, for the estimation of the economy 
indicator ECO, we considered as most important the 
AAB sub-indicator, giving emphasis to the revenues. 
Accordingly, for the ENV indicator, the most 
important sub-indicator is considered EEDI. This 
initial information is implemented to the modelling as 
ordinal weight restrictions of type “share” (see 
Section 3.2). The values resulted from the model 
application for the composite indicators ECO and 
ENV, appear in the last four columns of Table 1.  
The values of composite indicators ECO, ENV 
derived from models (1)-(2) appear in Table 2.  
Table 2: The values of the two composite indicators ECO, 
ENV obtained by Models (1), (2). 
  Model (1)  Model (2) 
Design ECO ENV ECO ENV 
REF  0.949 0.708 0.935 0.644 
d1  0.796 0.766 0.806 0.797 
d2  0.784 0.935 0.788 0.802 
d3  0.934 0.858 0.941 0.747 
d4  0.747 0.923 0.757 0.894 
d5  0.969 0.875 0.970 0.695 
d6  0.863 0.788 0.844 0.763 
d7  1.000 1.000 0.923 1.000 
d8  0.840 1.000 0.855 0.780 
d9  0.749 0.875 0.756 0.695 
d10  0.791 0.898 0.842 0.908 
d11  0.813 0.708 0.827 0.609 
d12  0.790 0.875 0.799 0.695 
d13  1.000 0.970 1.000 0.687 
d14  0.928 0.700 0.936 0.710 
d15  0.747 0.802 0.758 0.713 
d16  0.863 0.875 0.848 0.695 
d17  0.873 0.902 0.885 0.752 
d18  0.898 0.839 0.902 0.719 
 
Based on the results presented in Table 2, a 
number of remarks are possible. First, focusing on the 
results of model (1), several designs appear as 
superior (score equal to 1) in one of the two 
dimensions. This is the case for designs d7 and d13 
on economy (ECO indicator) and d7 and d8 on the 
environment (ENV indicator). Only design d7 is the 
best in both economics and environment and 
presumably this design is suggested as the optimum 
that achieves reduction of costs and the best 
environmental protection. Scores obtained from 
model (2) with common weights are lower that those 
from model (1). Consequently, alternative d8 loses its