Bus: DEFRA 🇬🇧

💡 High-Level Description:

DEFRA's methodology for calculating the carbon footprint of bus travel is based on standardized emission factors published by the UK government. These factors are derived from extensive national data sources and provide a reliable basis for estimating greenhouse gas emissions from different types of bus transportation.

DEFRA's methodology takes into account various bus categories, including local buses operating within and outside London, as well as long-distance coaches. Emissions are calculated based on factors such as fuel consumption, average occupancy rates, and energy efficiency. Additionally, DEFRA offers flexibility in emissions reporting by supporting two energy scopes: Tank-to-Wheel (TTW) and Well-to-Wheel (WTW), with WTW being the default option for a more comprehensive lifecycle assessment.

By leveraging DEFRA's well-established reporting framework, businesses and policymakers can ensure consistent and transparent carbon accounting for bus travel, aligning with UK environmental reporting regulations and sustainability strategies. Versioning: Use methodology_version to pin the DEFRA Conversion Factors year (e.g., "2024"). If omitted, SQUAKE uses the latest supported year.

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API Request

{
  "expand": ["items"],
  "items": [
    {
      "type": "bus",
      "external_reference": "test_1",
      "origin": "London",
      "destination": "Bristol",
      "bus_type": "coach",
      "number_of_travelers": 3,
      "energy_scope": "wtw",
      "methodology": "DEFRA",
      "methodology_version": "2024"
    }
  ]
}

API Request Items

• "type": "bus" (required)

• "methodology": "DEFRA" (required)

• "methodology_version": DEFRA Conversion Factors year (e.g., "2024"). Optional; if omitted → latest supported year.

• "external_reference": Correlate response to request (max 128 chars).

• "number_of_travelers": Minimum 1. Default: 1.

• "origin" / "destination": Postal, IATA/ICAO, UN/LOCODE, or "lat,lon".

• "distance_in_km": If present, overrides origin/destination.

• "bus_type" (options):

  • "local_bus_not_london"

  • "local_bus_london"

  • "average_local_bus" (default)

  • "coach"

• "energy_scope":

  • "wtw" (default) — well‑to‑wheel

  • "ttw" — tank‑to‑wheel

Default Values

• "bus_type": "average_local_bus"

• "energy_scope": "wtw"

• "methodology_version": latest supported DEFRA year

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Sample API Response

{
  "carbon_quantity": 15240,
  "carbon_unit": "gram",
  "items": [
    {
      "carbon_quantity": 15240,
      "carbon_unit": "gram",
      "external_reference": "test_1",
      "type": "bus",
      "methodology": "DEFRA",
      "methodology_version": "2024",
      "bus_type": "coach",
      "energy_scope": "wtw",
      "distance": 190.0,
      "distance_unit": "kilometer"
    }
  ]
}

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Versions

• Behavior: If methodology_version is omitted, SQUAKE automatically applies the latest supported DEFRA Conversion Factors year. Pin a specific year for reproducibility and auditability.

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Bibliography

• UK Government — Greenhouse Gas Emissions: Research & Statistics: https://www.gov.uk/environment/greenhouse-gas-emissions#research_and_statistics