Flight: CO2 emissiefactoren 🇳🇱

Calculate passenger flight emissions with the Dutch CO2-emissiefactoren factors, pinned to a published factor year or picked from the departure date.

type flightmethodology CO2-EMISSIEFACTOREN-NLFactor years 2020 and 2022Supports audit mode

CO2-emissiefactoren is a methodology from the Netherlands that provides emission factors across sectors, including passenger aviation, and is widely adopted by European stakeholders. For flights, it considers factors such as aircraft type, engine specifications, distance travelled and fuel efficiency, and it is updated to reflect the latest research and technology.

Versioning

Use methodology_version to pin a published factor year: "2020" for flights in 2020 and 2021, "2022" for flights from 2022 onward. If you leave it out, SQUAKE picks the year from departure_date; if neither is given, the latest version is used. See Versions.

Sample requests

Send a quote while the traveller is still choosing a flight, then repeat the call with audit set to true once the booking is final. The body is otherwise identical.

{
  "expand": ["items"],
  "items": [{
    "audit": false,
    "type": "flight",
    "methodology": "CO2-EMISSIEFACTOREN-NL",
    "external_reference": "string",
    "origin": "MIL",
    "destination": "ORY",
    "booking_class": "first",
    "energy_scope": "wtw",
    "number_of_travelers": 1,
    "radiative_forcing_index": true
  }]
}

audit_for is optional

Pass the ID of an auditable entity when you calculate on behalf of that entity. Otherwise, leave it out.

Defaults

When a field is missing, SQUAKE fills it in before calculating.

Field	Default	Applies when
`booking_class`	average	No `booking_class` is sent
`radiative_forcing_index`	`true`	No `radiative_forcing_index` is sent
`energy_scope`	`wtw`	No `energy_scope` is sent
`methodology_version`	Year of `departure_date`	No `methodology_version` is sent
`methodology_version`	Latest version	Neither `methodology_version` nor `departure_date` is sent

Request fields

typestringrequired

flight

methodologystringrequired

CO2-EMISSIEFACTOREN-NL

methodology_versionstring

The published factor year: 2020 (flights in 2020 and 2021) or 2022 (flights from 2022 onward). Optional. If you leave it out, the year is taken from departure_date, falling back to the latest version. See Versions.

departure_datestring

Departure date in YYYY-MM-DD format. Selects the factor year when methodology_version is left out.

originstring

IATA/ICAO airport code (MUC), UN/LOCODE for other locations (DEHAM), or latitude and longitude (+40.712,-74.006). For multi-leg trips, use routing instead.

destinationstring

Same formats as origin.

routingstring

Hyphen-separated airports for multi-leg itineraries, instead of origin and destination. See Flight: Routing (multi-leg).

distance_in_kmnumber

Takes priority over origin and destination. Without it, SQUAKE resolves the distance from them. With routing, per-leg distances apply.

booking_classenum

first, premium_economy, economy or business. Optional, defaults to average. If you leave it out, sending fare_class and airline is highly recommended so SQUAKE can resolve it.

fare_classstring

A single letter such as Y or J. Together with airline, mutually exclusive with booking_class.

airlinestring

IATA designator such as LH; airline names are resolved too.

radiative_forcing_indexboolean

Whether to apply a multiplier for the gases emitted at altitude. Defaults to true. See Radiative Forcing Index.

energy_scopeenum

ttw or wtw. Defaults to wtw.

number_of_travelersinteger

Minimum 1. Defaults to 1.

external_referencestring

Your identifier for the item, up to 128 characters, so you can match results to requests. SQUAKE doesn't guarantee the order of items.

sustainable_fuelsboolean

Marks the use of sustainable fuels. This lowers the emissions SQUAKE calculates, but isn't part of the current official frameworks.

carbon_reduction_percentage_of_totalnumber

Share of emissions reduced by sustainable fuel, from 0 to 1. Defaults to 0.

auditboolean

Set to true to create immutable audit records for finalised calculations. Must be enabled for your account.

See every field of POST /v2/calculations in the API reference

Sample response

200 OKapplication/json

{
  "carbon_quantity": 633654,
  "carbon_unit": "gram",
  "items": [{
    "carbon_quantity": 633654,
    "carbon_unit": "gram",
    "external_reference": "string",
    "type": "flight",
    "methodology": "CO2-EMISSIEFACTOREN-NL",
    "distance": 749.0,
    "distance_unit": "kilometer"
  }]
}

Versions

CO2-emissiefactoren publishes flight factors per vintage. SQUAKE supports two:

Version	Applies to	Notes
`2020`	Flights in 2020 and 2021	Factors are published per haul band only, with no travel-class split
`2022`	Flights from 2022 onward	Factors are published per travel class and haul band

SQUAKE picks the version in this order:

An explicit methodology_version, if you send one. This always wins, even when it disagrees with departure_date.
The year of departure_date, if no version was sent. A flight on 2020-05-01 or 2021-11-30 uses the 2020 factors; a flight on 2023-02-14 uses the 2022 factors.
The latest version, if neither is given.

A year that has no factor set of its own resolves to the most recent earlier year: 2021 resolves to 2020, and 2023 and later resolve to 2022. Years before 2020 are rejected with an invalid_methodology_version error.

The version actually used is returned as methodology_version on each item when you request "expand": ["items"], so a calculation stays reproducible:

Request

{
  "expand": ["items"],
  "items": [{
    "type": "flight",
    "methodology": "CO2-EMISSIEFACTOREN-NL",
    "origin": "MIL",
    "destination": "ORY",
    "departure_date": "2020-05-01",
    "number_of_travelers": 1
  }]
}

200 OKapplication/json

{
  "carbon_quantity": 149800,
  "carbon_unit": "gram",
  "items": [{
    "carbon_quantity": 149800,
    "carbon_unit": "gram",
    "type": "flight",
    "methodology": "CO2-EMISSIEFACTOREN-NL",
    "methodology_version": "2020",
    "distance": 749.0,
    "distance_unit": "kilometer"
  }]
}

No travel class in the 2020 factors

The 2020 factors have no travel-class dimension, so booking_class (and the fare_class and airline pair) doesn't change the result for flights priced with that version. Audit records for those calculations report the travel class actually priced, average.

Bibliography

Lijst emissiefactoren (2025). CO2 emissionfactoren. co2emissiefactoren.nl
Milieu Centraal (n.a.). milieucentraal.nl
Emissiefactoren van vliegverkeer in meer detail (January 2022). Milieu Centraal. Read the PDF. Factors for methodology_version 2022.
Emissiefactoren van vliegverkeer (2020). Milieu Centraal. co2emissiefactoren.nl. Factors for methodology_version 2020.

Flight: CO2 emissiefactoren 🇳🇱

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