# How do I split a footwear factory's emissions across different styles?

Canonical: https://senseible.earth/answers/footwear-factory-emissions-allocation-per-pair

Total the factory electricity at 0.710 kg CO2 per kWh and generator diesel at 2.68 kg per litre, then split by standard minutes per style rather than pairs, since a boot takes much longer to make than a sandal. State the rule beside each per-pair figure.

## Why pairs alone mislead

Dividing by pairs gives every style the same energy. Styles with more operations, such as boots with lasting and stitching, use more machine and lighting time.

## Rules that work

- Standard minute value (SMV) per style, from industrial engineering data.
- Machine hours per line, if lines are dedicated to styles.
- Pairs, only when styles are similar.

## Materials stay separate

Allocation covers factory energy. Leather, soles and components are added per style from the bill of materials.

## Worked example: pairs versus standard minutes (one month, illustrative inputs)

- Electricity: 70,000 kWh x 0.710 = 49,700 kg CO2
- Diesel: 900 litres x 2.68 = 2,412 kg CO2
- Factory total: 52,112 kg CO2 for 40,000 pairs
- By pairs: 52,112 / 40,000 = 1.303 kg CO2 per pair
- By standard minutes (boots 30, sandals 12; 10,000 boots, 30,000 sandals): boot 2.369 kg, sandal 0.947 kg

Inputs and minutes are illustrative; use your SMV data.

## 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.

- [Leather footwear per pair](https://senseible.earth/answers/leather-footwear-carbon-footprint-per-pair)
- [Allocating in a multi-product plant](https://senseible.earth/answers/multi-product-chemical-plant-emissions-allocation)
- [How scrap rate affects carbon per unit](https://senseible.earth/answers/how-scrap-rate-affects-carbon-per-unit)

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.