Using classification codes to estimate carbon emissions

Industry classification codes attempt to categorize human activities into a specific set of categories. These activities could be "Raising of dairy cattle" or "Rental and leasing of recreational and sports goods". Under a classification scheme each of these activities are then assigned a unique identifier, called a classification code.

Several well-known industry classifications exist, such as:

  • International Standard Industrial Classification (referred to as ISIC) which is the United Nations industry classification. The latest revision is ISIC4
  • Statistical Classification of Economic Activities in the European Community (referred to as NACE), which is a european version of ISIC. The latest revision is NACE2

Some datasets that Climatiq incorporates publish classification codes along with their emission factors. When this is the case, Climatiq allows you to make carbon estimations based on these classification codes.

Below is a table of the industry classification codes Climatiq supports, and the datasets that are mapped to them.

As an example, let's take the ISIC4 classification code 25, which is "Manufacture of fabricated metal products, except machinery and equipment". If one of the datasets listed above has an emission factor that's mapped to the ISIC4 classification scheme and has an emission factor that corresponds to the ISIC4 code 25, you can make a carbon estimation for that classification code like this:

curl --request POST \
--url \
--header 'Authorization: Bearer API_KEY' \
--data '{
"classification": {
"classification_type": "isic4",
"classification_code": "25"
"parameters": {
"money": 25.0,
"money_unit": "usd"

And you will get the following response back.

"co2e": 38.4025,
"co2e_unit": "kg",
"co2e_calculation_method": "ar4",
"co2e_calculation_origin": "source",
"emission_factor": {
"activity_id": "metals_primary-type_basic_metals_fabricated_metal",
"uuid": "82e29151-4e51-41c4-af64-6bf9322b2900",
"id": "metals_primary-type_basic_metals_fabricated_metal",
"access_type": "public",
"source": "GHG Protocol",
"year": "2017",
"region": "GLOBAL",
"category": "Metals",
"lca_activity": "unknown",
"data_quality_flags": []
"constituent_gases": {
"co2e_total": 38.4025,
"co2e_other": null,
"co2": null,
"ch4": null,
"n2o": null

Multiple emission factors from different datasets might map to the same classification code. If you have a specific emission factor you want to use, you can also filter your selection by specifying a year, source, region or more. See the full API documentation for more details on what you can filter on.

Multiple valid emission factors
If multiple emission factors match a specific query, such as when multiple sources specify an emission factor for the same activity, Climatiq will pick the newest one. However, if there are multiple emission factors from the same year valid for the query, the most conservative (the one with the highest co2e), will be picked instead.

The different industry classification such as ISIC4, NACE2 and others are different, but often many classification codes overlap, or are identical. The United Nations publishes correspondence tables that explain how you can go from one industry classification to another.

Climatiq uses these tables to make more data available for you. If you query with an NACE2 code that has no corresponding emission factor, Climatiq will attempt to map that NACE2 code to classification codes available in other industry classifications, such as ISIC4, and if successful might give you an emission factor based on a corresponding ISIC4 code.

Mappings between classification schemes aren't perfect. To avoid imprecise estimates, Climatiq will first search the datasets that have been mapped directly to the classification code you provide (primary datasets in the "supported industry classifications table above).

Only if no emission factors can be found from a primary dataset, will Climatiq then search other industry classification schemes.

As always after performing an estimate, you should check the used emission factor to ensure that it is a sensible one.