The methodology used to calculate the ecoscore follows the steps based on life cycle assessment: inventory, classification, characterisation, normalisation and weighting. It is applied on a well-to-wheel approach (WTW), including exhaust emissions (direct emissions, tank to wheel or TTW) and emissions from the fuel production and distribution (indirect emissions, well to tank or WTT). All emissions are classified into three damages: climate change, air quality (divided into two sub damages: human health and ecosystems) and noise.
Remark: the detailed sheet for an individual vehicle in the search section of the website only contains tank-to-wheel CO2 emissions (TTW), i.e. exhaust emissions. For most cars, these TTW emissions are more important in the total WTW emissions than the WTT emissions, although some exceptions exist (e.g., full-electric vehicles that don't have exhaust emissions).
Different impact factors are used to characterise the contribution of each pollutant to the damage category they belong to:
Table 1: Overview of the damages category and the corresponding pollutants
*the methodology takes into account whether pollutants are emitted in an urban or rural area. For well-to-tank emissions, rural values are used. For exhaust emissions, a weighted average of urban and rural external costs is used, based on the national split between urban and rural mileage as a weight factor. That mileage distribution comes from the FPS Mobility.
The total impacts are normalized for each damage category and vehicle, given the damages associated with a reference vehicle. The reference for a passenger car is defined as a petrol car that meets the Euro 4 emission standard with CO2 emissions of 120 g/km.
The weighing of the three impact categories into one indicator is based on the weights that are the result of a borad stakeholder survey. These weights can be found in the following figure:
The simplified formula for the calculation of the Ecoscore of light-duty vehicles
The methodology to calculate the ecoscore has been translated to one formula that can be found below. It contains coefficients (A,B,C,D,E,F,G,H) of which the value depends on the fuel and Euro stage of the vehicle (see Table 2).
Ecoscore = 100*exp[-0.00357*(A * CO2 + B * THC + C * NOx + D * CO + E * PM + F * FC + G * dB(A) + H)]
Of which the following parameters are mentioned on the certificate of conformity of a vehicle (a dedicated section for PHEV can be found a bit further):
CO2
CO2 emission (combined) (g/km)
THC
petrol, LPG and CNG: THC emission (g/km)
diesel: the difference between the THCNOx and the NOx emissions (g/km)
NOx
petrol, CNG and LPG: NOx emission (g/km)
diesel:
Euro 0 till Euro 5: 0.63 g/km
Euro 6: 0.50 g/km
CO
CO emission (g/km)
PM
particulate matter emissions (g/km)
FC
petrol, diesel and LPG: the average (or combined) fuel consumption (l/100km)
CNG: the average (or combined) fuel consumption (kg/100km)
EV: the average (or combined) electricity consumption (kWh/100km)
dB(A)
noise level while driving (dB(A))
and with the coefficients A, B, C, D, E, F, G and the constants H corresponding to the values in the table below, depending on fuel type and Euro stage.
Table 2: Value of the coefficients per fuel and euro standard
This formula is a bit different for PHEV petrol and diesel cars:
To calculate the Ecoscore of PHEV vehicles, the weighted combined CO2 emissions and fuel consumption should be used. RangeV refers to the electric range.
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