Car: DEFRA π¬π§
π‘ High-Level Description
The Department for Environment, Food & Rural Affairs (DEFRA) of the UK has been a stalwart in environmental governance and establishing methodologies across various sectors. Within the car sector, DEFRA's methodology focuses keenly on providing robust and comprehensible metrics for carbon emissions. Recognizing the massive contribution of vehicles to the UK's carbon footprint, DEFRA's guidelines are tailored to encompass the diverse range of vehicles on the roads, from compact cars to SUVs.
DEFRA's approach not only accounts for direct emissions derived from fuel combustion but also considers the broader life-cycle emissions of vehicles, including manufacturing, maintenance, and disposal. Their methodology, backed by extensive research and consultation with automotive industry experts, provides a solid foundation for the UK's policy-making, encouraging sustainable car manufacturing and usage. Through DEFRA's efforts, consumers, manufacturers, and policymakers are better equipped to make environmentally conscious decisions regarding transportation.
Versioning: Use methodology_version
to pin a specific Conversion Factors year (e.g., "2024"
). If omitted, SQUAKE uses the latest supported year.
Sample API Requests
A. Route-based request (origin/destination or explicit distance)
{
"expand": ["items"],
"items": [
{
"type": "car",
"methodology": "DEFRA",
"external_reference": "string",
"origin": "Frankfurt am Main, Germany",
"destination": "Berlin, Germany",
"fuel_type": "hev",
"car_type": "dual_purpose_4x4",
"energy_scope": "ttw",
"methodology_version": "2024"
}
]
}
B. Duration-based request (fallback when distance is unknown)
When the trip distance is unknown, you may pass
number_of_days
. The API will estimate the distance asestimated_distance_in_km = number_of_days * 60
.
{
"expand": ["items"],
"items": [
{
"type": "car",
"methodology": "DEFRA",
"external_reference": "string",
"fuel_type": "hev",
"car_type": "dual_purpose_4x4",
"energy_scope": "ttw",
"methodology_version": "2024",
"number_of_days": 5
}
]
}
Precedence rule: If
distance_in_km
is provided, it will be used and takes priority over bothorigin
/destination
andnumber_of_days
.
Sample API Response
{
"carbon_quantity": 10764,
"carbon_unit": "gram",
"items": [
{
"carbon_quantity": 10764,
"carbon_unit": "gram",
"external_reference": "string",
"type": "car",
"methodology": "DEFRA",
"methodology_version": "2024",
"distance": 110.0,
"distance_unit": "kilometer"
}
]
}
API Request Items
"type"
:"car"
(required)"methodology"
:"DEFRA"
(required)"methodology_version"
: DEFRA Conversion Factors year (e.g.,"2024"
). Optional; if omitted β latest supported year."external_reference"
: Unique identifier to correlate responses (max 128 chars)."origin"
/"destination"
: Postal, IATA/ICAO, UN/LOCODE, or"lat,lon"
; SQUAKE resolves distance."distance_in_km"
: If present, overrides origin/destination resolution andnumber_of_days
."number_of_days"
: integer (display name: Number-Of-Days), >= 1.Use when trip distance is unknown.
Estimated distance formula:
estimated_distance_in_km = number_of_days * 60
.Precedence:
distance_in_km
>origin/destination
>number_of_days
(fallback).
"fuel_type"
:"petrol"
,"diesel"
,"hev"
,"phev"
,"electricity"
,"average"
(default:"average"
)."acriss_car_type"
: ACRISS segment letters (e.g.,C
,D
,E
,F
,G
,H
,I
,J
,L
,M
,N
,P
,R
,S
,U
,W
,X
,O
). Mutually exclusive with"car_type"
."sipp_car_type"
: Ifacriss_car_type
not passed, can be used to infer class. Mutually exclusive with"car_type"
."car_type"
:"mini"
,"supermini"
,"lower_medium"
,"upper_medium"
,"executive"
,"luxury"
,"sports"
,"dual_purpose_4x4"
,"mpv"
,"small"
,"medium"
,"large"
,"average"
(default:"average"
)."energy_scope"
:"wtw"
(default) or"ttw"
.
Default Values
"fuel_type": "average"
"car_type": "average"
"energy_scope": "wtw"
"methodology_version"
: latest supported DEFRA year
Notes
Data quality tip: whenever possible, pass the actual
distance_in_km
βit yields the most accurate result.number_of_days
is a convenience fallback and a coarse approximation.Pin
methodology_version
for reproducibility and auditability in long-lived reports.If neither
distance_in_km
nororigin
/destination
are supplied, the API will usenumber_of_days
(if provided) to estimate distance; otherwise the request may be insufficient to compute trip emissions.
Bibliography
UK Government β Greenhouse gas emissions: Research & statistics: https://www.gov.uk/environment/greenhouse-gas-emissions#research_and_statistics
Bramwell, R., et al. (2024). Government Greenhouse Gas Conversion Factors for Company Reporting β Methodology. (Methodology paper PDF).
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