Use Classification Codes

Using Classification Codes to Estimate Carbon Emissions

This guide explores what classification codes are, the various industry classifications supported, and how to use them with Climatiq.

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What Are Industry Classification Codes?

Industry classification codes attempt to categorize human activities into a specific set of categories like "Raising of dairy cattle" or "Rental and leasing of recreational and sports goods". These activities are assigned a unique identifier, known as a classification code, under a classification scheme.

Various internationally recognized industry classifications include:

  • International Standard Industrial Classification (ISIC (opens in a new tab)) which is the United Nations industry classification. The latest revision is ISIC4.
  • Statistical Classification of Economic Activities in the European Community (NACE (opens in a new tab)), which is a european version of ISIC. The latest revision is NACE2
  • Merchant Category Codes (MCC (opens in a new tab)) used to categorize merchants, commonly used for financial transactions.
  • United Nations Standard Products and Services Code (UNSPSC (opens in a new tab)), a UN standard used to categorize products and services.
  • North American Industry Classification System (NAICS (opens in a new tab)), which is a standard used by federal statistical agencies in classifying business establishments. The latest revision is NAICS2017.

Classification Codes Supported by Climatiq

Climatiq integrates some datasets that publish emission factors along with classification codes. This feature allows you to estimate carbon emissions based on these classification codes.

Here's a table of the industry classification codes supported by Climatiq and their corresponding datasets:

Industry Classification CodePrimary DatasetNotes
ISIC Rev. 4 (opens in a new tab)GHG Protocol (opens in a new tab)(via ISIC 3.1)
NACE Rev. 2 (opens in a new tab)EXIOBASE3 (opens in a new tab)
Merchant Classification Codes (MCCs) (opens in a new tab)EXIOBASE3 (opens in a new tab)
United Nations Standard Products and Services Code (UNSPSC) (opens in a new tab)EXIOBASE3 (opens in a new tab)Currently only works for UNSPSC family level codes
North American Industry Classification System (NAICS) (opens in a new tab)U.S. Government (EPA) (opens in a new tab)

Using Classification Codes to Estimate Carbon Emissions with Climatiq

As an example, let's take the ISIC4 classification code 25, "Manufacture of fabricated metal products, except machinery and equipment". If an emission factor is mapped to the ISIC4 classification scheme and corresponds to the ISIC4 code 25, you can estimate carbon emissions for that classification code as follows:

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

The resulting response would look like this:

"co2e": 49.25,
"co2e_unit": "kg",
"co2e_calculation_method": "ar5",
"co2e_calculation_origin": "source",
"emission_factor": {
"name": "Fabricated metal products/except machinery and equipment",
"activity_id": "metal_products-type_fabricated_metal_products_except_machinery_equipment",
"id": "79e87731-dc29-470b-a2fa-73e30797bc53",
"access_type": "public",
"source": "EXIOBASE",
"source_dataset": "EXIOBASE 3",
"year": 2019,
"region": "IN",
"category": "Fabricated Metal Products",
"source_lca_activity": "unknown",
"data_quality_flags": []
"constituent_gases": {
"co2e_total": 49.25,
"co2e_other": null,
"co2": null,
"ch4": null,
"n2o": null
"activity_data": {
"activity_value": 22.35,
"activity_unit": "eur"
"audit_trail": "enabled",
"source_trail": [
"data_category": "emission_factor",
"name": "Fabricated metal products/except machinery and equipment",
"source": "EXIOBASE",
"source_dataset": "EXIOBASE 3",
"year": "2019",
"region": "IN",
"region_name": "India"

Tailoring Your Search with Additional Filters

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

When multiple emission factors satisfy a specific query, Climatiq will select the newest one. If there are multiple emission factors from the same year, the most conservative (highest co2e) is chosen.

Traversing Classification Schemes

Different industry classifications such as ISIC4, NACE2, and others, often share overlapping or identical classification codes. The United Nations provides correspondence tables (opens in a new tab) to assist in transitioning from one industry classification to another.

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

However, transitions between classification schemes aren't perfect. To prevent inaccurate estimates, Climatiq initially searches datasets directly mapped to the classification code you provide (primary datasets in the "supported industry classifications table" above).

Only when no emission factors are found in a primary dataset does Climatiq then search other industry classification schemes.

Remember, after estimating, always review the used emission factor to ensure its validity and accuracy.