How do I split a chemical plant's emissions between its products?
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.
Sources: GHG Protocol Corporate Value Chain (Scope 3) Standard, IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults), CEA CO2 Baseline Database, version 21.0
Last reviewed 2026-10-21.