Methodology for comparing the consumption of liquid fuels in transport.
The calculation of greenhouse gas (GHG) and pollutant emissions for the entire transport sector is based on the unified framework of UNFCCC/ETF, IPCC Good Practice Guidance, the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, and the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The methodology relies on two main input data groups: activity data (fuel consumption for road, rail, maritime, aviation, and pipeline transport) converted to energy content according to national statistics, and emission factors. For road transport, the COPERT model is used, providing detailed emission factors for different emission standards (Euro 0–Euro 6), vehicle categories, and fuel types, including non-exhaust PM and NMVOC emissions (Tier 2 accuracy level). For other transport modes, emission factors are derived from the EMEP/EEA Guidebook, specialized international manuals (EUROCONTROL), and national measurements of carbon content in fuels.
For road transport, the COPERT model is used, providing detailed factors for different emission standards (Euro 0 – Euro 6), vehicle categories, and fuel types, including non-exhaust PM and NMVOC emissions (Tier 2 level of accuracy). For other transport modes, emission factors are sourced from the EMEP/EEA Guidebook, specialized international manuals (EUROCONTROL), and national measurements of fuel carbon content.
Each combination of “activity data × emission factor” is processed according to the IPCC Tier classification:
- Tier 1: basic global IPCC factors for quick estimates
- Tier 2: national factors adjusted for fleet structure and local conditions
- Tier 3: dynamic operational modelling and direct measurements for maximum accuracy
The inventory includes quality assurance/control (QA/QC) according to UNFCCC Good Practice Guidance, uncertainty assessment, and inter-ministerial verification before official reporting, ensuring consistency and transparency of data.
Accurate emissions calculations require detailed traffic intensity data and, most importantly, total fuel consumption. To harmonize fuel consumption outputs from official sources, a methodology was published in January 2021.
For modelling road transport emission projections up to 2050, the COPERT model is used with an extended Command Line Interface (CLI). The dataset for projections was prepared in collaboration with colleagues from Aristotle University of Thessaloniki and based on assumptions from the Sybil database. These data were adjusted according to the latest vehicle fleet information and anticipated policies and measures.
For other transport modes, an ARIMA model was used.
Policies and measures are divided into four categories:
- Measures affecting transport performance at the national level (modal shift)
- Measures influencing emission factors (EU directives)
- “Soft” measures that cannot be quantified
- Measures that can be quantified but not at the national level (integrated transport systems, non-motorized transport)