# Flight: TU Chalmers 🇸🇪

### 💡 High-Level Description:

The **TU-Chalmers methodology** originates from research conducted by Chalmers University of Technology, one of Sweden’s leading institutions in environmental and energy sciences. This methodology is grounded in academic research that focuses on improving the precision of greenhouse gas (GHG) calculations for air travel. It integrates detailed parameters such as booking class, flight type (scheduled or charter), and the use of biofuels to offer a refined understanding of aviation emissions.

TU-Chalmers stands out for its consideration of passenger class-specific emissions (reflecting differences in space usage and associated fuel allocation) and for enabling assessments of flights utilizing biofuels. This approach is particularly beneficial for academic institutions, sustainability auditors, and airlines aiming to implement climate-conscious travel policies and carbon reporting practices.

***

### **Sample API Requests**

#### A. Without audit mode (for pre-booking/quotes)

```json
{
  "expand": ["items"],
  "items": [
    {
      "audit": false,
      "type": "flight",
      "methodology": "TU-CHALMERS",
      "external_reference": "test_1",
      "number_of_travelers": 1,
      "origin": "FRA",
      "destination": "JFK",
      "booking_class": "premium_economy",
      "plane_type": "scheduled",
      "biofuel": true
    }
  ]
}
```

#### B. With audit mode (for finalized/post-booking calculations)

```json
{
  "expand": ["items"],
  "audit_for": "<Auditable Entity ID>",
  "items": [
    {
      "audit": true,
      "type": "flight",
      "methodology": "TU-CHALMERS",
      "external_reference": "test_1",
      "number_of_travelers": 1,
      "origin": "FRA",
      "destination": "JFK",
      "booking_class": "premium_economy",
      "plane_type": "scheduled",
      "biofuel": true
    }
  ]
}
```

> **Note:** `audit_for` is optional. Provide when calculating on behalf of a specific Auditable entity; otherwise omit.

***

### **API Request Items**

* `"type": "flight"` (required)
* `"methodology": "TU-CHALMERS"` (required)
* `"external_reference"`: A unique identifier to help link the resulting emissions to the specific request. This is useful when multiple items are submitted. Max length is 128 characters.
* `"number_of_travelers"`: Minimum value is `1`. Default value is `1`.
* `"origin"`: For airports use IATA/ICAO code (format: `^[A-Z]{3,4}$`, e.g. `"MUC"`), for other locations used in trade and transportation use UN/LOCODE codes (format: `^[A-Z]{2}\W?[A-Z2-9]{3}$`, e.g. `"DEHAM"`). You can also pass lat/long (format: `^[-+]?\d{1,3}\.\d{1,10}\s?,\s?[-+]?\d{1,3}\.\d{1,10}$`, e.g. `"+40.712,-74.006"`).
* `"destination"`: For airports use IATA/ICAO code (format: `^[A-Z]{3,4}$`, e.g. `"MUC"`), for other locations used in trade and transportation use UN/LOCODE codes (format: `^[A-Z]{2}\W?[A-Z2-9]{3}$`, e.g. `"DEHAM"`). You can also pass lat/long (format: `^[-+]?\d{1,3}\.\d{1,10}\s?,\s?[-+]?\d{1,3}\.\d{1,10}$`, e.g. `"+40.712,-74.006"`).
* Multi-leg itineraries: use **`routing`** (hyphen-separated airports) instead of `origin`/`destination` — see [**Flight: Routing (multi-leg)**](/api-calculations-request-response/travel/flight/flight-routing.md).
* `"distance_in_km"`: If provided, it overrides `origin` and `destination`. If omitted, distance is resolved automatically using `origin` and `destination` (not used as the routed total when **`routing`** is set; see Flight: Routing).
* `"booking_class"`: Indicates the travel class. Supported values include: `economy`, `premium_economy`, `business`, and `first`. This affects emissions based on the space and resource allocation per passenger.
* `"plane_type"`: Specifies whether the flight is a `"scheduled"` service or a `"charter"` flight. Default value is `"scheduled"`.
* `"biofuel"`: A boolean (`true` or `false`) indicating whether biofuel was used for the flight. Default is `false`.
* `"audit"`: boolean (optional). Set to `true` to create immutable audit records for finalized calculations. Must be enabled for your account.

***

### **Sample API Response**

```json
{
    "carbon_quantity": 632000,
    "carbon_unit": "gram",
    "items": [
        {
            "carbon_quantity": 632000,
            "carbon_unit": "gram",
            "external_reference": "test_1",
            "type": "flight",
            "methodology": "TU-CHALMERS",
            "distance": 6320.0,
            "distance_unit": "kilometer"
        }
    ]
}
```

***

### **Bibliography**

* Methodology Report for Travel and Climate (Version 4.1). Chalmers University of Technology. Retrieved from <https://travelandclimate.org/method/Methodology-Report-for-Travel-and-Climate-Version-4-1.pdf>


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