Computer model to calculate emissions from road traffic

COPERT is the EU standard vehicle emissions calculator. It uses vehicle population, mileage, speed and other data such as ambient temperature to calculate emissions and energy consumption from road transport. It incorporates results of several technology, research, and policy assessment projects. The main purpose of the model is to facilitate national experts to compile their emissions inventory, but the scope of the model goes beyond that. COPERT can be used as a policy assessment tool for any type of environmental studies. The model can also act as a reference point for researchers to find information on the emission and energy consumption levels of any type of new vehicles existing on the European roads but also older vehicle technologies which might still exist.

The model consists of 3 main parts; the input part, the emission factor part (in consistency with the EMEP/EEA Emission Inventory Guidebook, based on Tier 1/2/3 methods), and the results part, where the calculated emissions are presented. Estimated emissions are grouped in four sources; emissions produced during thermally stabilized engine operation (hot emissions), emissions occurring during engine start from ambient temperature (cold-start and warming-up effects), and non-exhaust emissions from fuel evaporation, tyre, brake and road wear. Some additional emissions for all driving modes are calculated due to the use of an A/C. Total emissions are calculated as a product of activity data provided by the user and speed-dependent emission factors provided by the software as a result of RDE measurement data.

There is also the energy balance feature; the activity data is most frequently modified so that calculated energy consumption meets the statistical one reported by each country. In this case, a mileage correction factor (MCF)and the biofuel content correction factor are applied to the mean activity to balance the statistical and calculated energy consumption. The spatial scale of the model can range from a region to country level. The temporal extension of COPERT can also range from annual to multi-annual, although it actually depends on the activity data provided. This means that the calculation period can range from a year to a number of years (from 1990 to 2050).

COPERT can be used for policy anticipation, implementation and evaluation for air quality related policies. It can be used for trend analysis, and input for air quality modelling and impact assessment studies, either directly or after some modifications, sometimes in combination with other emission models (e.g. SIBYL). It has been recently used for the assessment of the emissions from battery electric vehicles, the introduction of Euro 7 emission standards for cars, vans, trucks and buses, and the revised procedure for non-exhaust emissions.

COPERT applies EEA’s EMEP/EEA air pollutant emission inventory guidebook version 2023 (updated in 2024), and more specifically chapter 1.A.3.b.i-iv Road transport 2024. The model structure is split in three parts; input, emission factor calculation and results.

COPERT includes 530 vehicle categories (205 cars, 72 vans, 137 trucks, 70 buses, 46 l-category vehicles) divided per load capacity (trucks & buses) of engine capacity (other vehicles), Euro emission standard, fuel type:

• Passenger Cars:
  • Fuels: Petrol, Petrol Hybrid, Petrol PHEV, Diesel, Diesel PHEV, LPG Bifuel, CNG Bifuel, Battery electric
  • Segments: Mini, Small, Medium, Large-SUV-Executive, 2-Stroke
  • Euro standards: from Conventional to Euro 7
• Light Commercial Vehicles:
  • Fuels: Petrol, Diesel, Battery electric
  • Segments: N1-I, N1-II, N1-III
  • Euro standards: from Conventional to Euro 7
• Heavy Duty Trucks:
  • Fuels: Petrol, Diesel, CNG, LNG
  • Segments: Rigid, Articulated
  • Euro standards: from Conventional to Euro VII
• Buses:
  • Fuels: Diesel, Diesel Hybrid, Battery electric, CNG, Biodiesel
  • Segments: Urban Buses (Midi, Standard, Articulated), Coaches (Standard, Articulated)
  • Euro standards: from Conventional to Euro VII
• L-Category:
  • Fuels: Petrol, Diesel
  • Segments: Mopeds 2-stroke, Mopeds 4-stroke, Motorcycles 2-stroke, Motorcycles 4-stroke, Quad & ATVs, Micro-car
  • Euro standards: from Conventional to Euro 5

Inputs for each of them can be divided into required and desired:

• Required inputs:
  • Population (stock)
  • Mileage (mean activity)
  • Lifetime cumulative activity
  • Average speed in urban/rural/highway streets
  • Share of km run in urban/rural/highway streets
• Desired inputs:

• Load factor and road slope for trucks and buses
• Size of tank and canister (for the evaporative part of the emissions only)
• Percentage of evaporation in urban/rural/highway streets (for the evaporative part of the emissions only)
• Environmental conditions (minimum and maximum monthly average temperature (for the cold part of the emissions only), humidity (for the impact of the A/C use), Reid vapor pressure)
• Fuel type characteristics (content of metals in the fuel, ratio of hydrogen to carbon and oxygen to carbon, heavy metal content, density, fuel energy content, biofuel content)
• Trip characteristics (length, duration)
• A/C options (A/C usage, vehicles with A/C, A/C effect)
• Energy balance (total fuel sales)
• CO2 parameters (CO2 reduction, SCR CO2 emissions)
• Utility factor (for PHEV vehicles)

Parametrizations: The model contains a dataset of emission factors (grams of pollutants per kilometer and energy consumption per kilometer) derived from measurements for urban/rural/highway operations. Depending on the input vehicle speed, the model calculates the appropriate emission or energy consumption factor. Using the vehicle population, mileage and share of kilometers driven in each road type, the model calculates the total emissions and energy consumption. If more detailed information is available, the user can provide his own emission factors to be used for the calculation of emissions.

The model also contains parametrization for simulating additional CO2 emissions due to:

• using the air condition
• lube oil consumption using different SCR rates (an abatement technology for NOx)

or improve emission calculation for NOx, CO and VOC by taking into account the vehicle age.

CO2 emission calculation can be further improved by providing information on real-world CO2 data for passenger cars.

If statistics on the energy/fuel consumption (sales) are provided as input to the model, the emissions are rescaled and adjusted to reach consistency.