Car: DEFRA is Now Available

Car DEFRA Methodology Update 2024

In 2024, the DEFRA methodology for carbon emission calculations from passenger vehicles has been updated to align with the latest Greenhouse Gas (GHG) reporting conversion factors. These updates focus on direct emissions from vehicles, covering both Scope 1 and Scope 3 emissions from petrol, diesel, and electric vehicles. The updated conversion factors ensure businesses can accurately report their land transport-related emissions for compliance and sustainability reporting.

Summary of Key Updates

The key updates for passenger vehicles in 2024 include:

  • PHEV Utility Factors: The 2024 update introduces revised utility factors for plug-in hybrid electric vehicles (PHEVs) to better reflect real-world emissions data. The proportion of distance traveled in electric mode has been decreased, accounting for the actual battery usage and increased fuel consumption in real-world driving.

  • Electric Vehicles: The update also includes more accurate conversion factors for electric vehicles (EVs), reflecting transmission and distribution losses (Scope 2) and well-to-tank (WTT) emissions (Scope 3) associated with electricity consumption.

  • Passenger Vehicles Data: Conversion factors for petrol and diesel vehicles continue to incorporate real-world performance uplifts based on driving conditions and regulatory test cycles, particularly transitioning from the New European Driving Cycle (NEDC) to the Worldwide Harmonized Light Vehicle Test Procedure (WLTP).

Key Methodological Considerations

  • Real-World Driving Adjustments: The update applies uplifts to account for differences between regulatory test emissions and real-world vehicle performance. These adjustments are based on studies conducted by the International Council on Clean Transportation (ICCT) and other UK-based sources.

  • Segmented Emission Factors: Conversion factors have been segmented by vehicle type (e.g., petrol, diesel, PHEV) and engine size, ensuring a granular approach to emission calculations.

  • Hybrid and Electric Vehicles: For hybrid and electric vehicles, real-world utility factors and electric range data have been revised to more accurately reflect emissions from electric and hybrid operations.

For full details on the 2024 GHG conversion factors for passenger vehicles, visit the UK Government website.

Bibliography

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