Ecoscore calculation

Ecoscore

Ecoscore calculation


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, including exhaust emissions (direct emissions) and emissions from the fuel production and distribution (indirect emissions). 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 only contains tank-to-wheel emissions, i.e., fuel-cycle 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).
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, the corresponding pollutants and sources to find them Notes: *the methodology provides values for pollutants emitted in an urban or non-urban area. For well-to-tank emissions, non-urban values are used. A weighted average of urban and rural external costs for exhaust emissions is used based on the national split between urban and rural mileage as a weight factor. Such mileage distribution comes from the Belgian National Institute of Statistics (NIS).

Table 1: Overview of the damages category, the corresponding pollutants and sources to find them
Notes: *the methodology provides values for pollutants emitted in an urban or non-urban area. For well-to-tank emissions, non-urban values are used. A weighted average of urban and rural external costs for exhaust emissions is used based on the national split between urban and rural mileage as a weight factor. Such mileage distribution comes from the Belgian National Institute of Statistics (NIS).

The total impacts are normalized for each damage category and vehicle, given the damages associated with a reference vehicle. The reference for a passenger vehicle is defined as a vehicle 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 you find in the following figure:
The adapted formula for the calculation of the ecoscore of light-duty vehicles

The adapted 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 is displayed in the table 2 and depend on the fuel and Euro stage of the vehicle (and some other parameters).
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
  • for petrol, LPG and CNG vehicles: THC emission (g/km)
  • for diesel vehicles: the difference between the THCNOx and the NOx emissions (g/km)

NOx
  • for petrol, CNG and LPG: NOx emission (g/km) 
  • for diesel vehicles
    • for vehicles complying with Euro 0 till Euro 5, this is 0.63 g/km. 
    • for vehicles complying with Euro 6, this is 0.50 g/km

CO
  • for all fuels: CO emission (g/km)

PM
  • for all fuels: particulate emissions (g/km)

FC
  • for petrol, diesel and LPG vehicles: the average fuel consumption (combined), expressed in l/100km 
  •  for CNG: the average fuel consumption (combined), expressed in kg/100km 
  •  for EV:  the average electricity consumption (combined), expressed in kWh/100km

dB(A)
  • the noise level (driving), expressed in 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, each time subdivided per 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 and vans:

PHEV petrol Euro 5 & 6:
  • Ecoscore = 100*exp[-0.00357*(0,36*CO2 + 23,17*HC + 101,88*NOx + 0,011*CO + 1407,75*PM + 7,01*FCptr + 2,17*FCEV+ 0,333*dB(A) – 12,98)]

PHEV diesel Euro 5:
  • Ecoscore = 100*exp[-0.00357*(0,36*CO2 + 23,17*HC + 101,88*0,63*25/(25+RangeEV) + 0,011*CO + 1407,75*PM + 5,19*FCdsl + 2,17*FCev+ 0,333*dB(A) – 12,86)]

PHEV diesel Euro 6:
  • Ecoscore = 100*exp[-0.00357*(0,36*CO2 + 23,17*HC + 101,88*0,5*25/(25+RangeEV) + 0,011*CO + 1407,75*PM + 5,19*FCdsl + 2,17*FCev+ 0,333*dB(A) – 12,86)]

Of which the parameters are also mentioned on the certificate of conformity of a vehicle:
CO2
  • CO2 emission (weigthed combined) (g/km)

FC's
  • the weighted petrol or diesel consumption (weigthed combined) in l/100km and the (weighted combined) electricity consumption (FCev) in kWh/100km

dB(A)
  • the noise level (driving), expressed in dB(A)

RangeEV
  • the range (km) of the PHEV in electricity only mode