# How do I split a chemical plant's emissions between its products?

Canonical: https://senseible.earth/answers/multi-product-chemical-plant-emissions-allocation

Measure what you can per product, such as dedicated reactors or steam lines, then split the shared energy by a stated rule, such as mass of output, or batch hours when products need very different heating. Keep the rule the same each year and state it with every product figure.

## Order of preference

- Direct measurement: sub-meters or steam meters per line.
- Physical allocation: kilograms of output or reactor hours.
- Economic allocation by revenue, only when physical rules do not fit.

## Why the rule matters

Mass allocation gives every kilogram the same share, even if one product needs twice the heating. If heating time differs a lot, reactor hours or steam per batch give a fairer split.

## What a buyer sees

Give the per-kilogram figure, the rule used and the share of energy that was directly metered, so the buyer can judge how close the number is to the product.

## Worked example: mass allocation (one month, illustrative inputs)

- PNG: 30,000 scm x 2.05 = 61,500 kg CO2
- Electricity: 60,000 kWh x 0.710 = 42,600 kg CO2
- Plant total: 104,100 kg CO2 for 500 t of output
- Product A, 320 t: 104,100 x 320 / 500 = 66,624 kg CO2
- Product B, 180 t: 104,100 x 180 / 500 = 37,476 kg CO2
- Per kg, either product: 104,100 / 500,000 = 0.208 kg CO2

Inputs are illustrative; ISO 14067 and the GHG Protocol Product Standard set the allocation order.

## What Senseible does here

Senseible reads the energy invoices behind the making stage into a fingerprinted Scope 1 and 2 record, and keeps material invoices on the Scope 3 trail. Material factors come from your supplier or a named database and are labelled with their source, so the product figure can be traced line by line.

- [CHP allocation between power and steam](https://senseible.earth/answers/chp-emissions-allocation-electricity-and-steam)
- [Pharma cleanroom HVAC allocation](https://senseible.earth/answers/pharma-cleanroom-hvac-emissions-allocation)
- [Answer a TfS PCF request](https://senseible.earth/answers/answer-a-tfs-pcf-request-chemical-supplier)

Sources: [GHG Protocol Corporate Value Chain (Scope 3) Standard](https://ghgprotocol.org/corporate-value-chain-scope-3-standard), [IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults)](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [CEA CO2 Baseline Database, version 21.0](https://cea.nic.in/cdm-co2-baseline-database/?lang=en)

Last reviewed 2026-10-21.