# How do I calculate the carbon footprint of a leaf spring?

Canonical: https://senseible.earth/answers/leaf-spring-carbon-footprint-per-tonne

Start with the spring steel flats per tonne of springs and the steel supplier's figure. Add cutting, eye rolling, heat treatment, shot peening and painting energy, then divide the plant's energy by tonnes dispatched.

## Material

- Spring steel flats.
- Bushes, clips and centre bolts.
- Paint.

## Process

- Cutting, tapering and eye rolling, often with heating.
- Hardening and tempering.
- Shot peening, assembly and painting.

## Per tonne

Report per tonne, or per spring assembly by weight. Furnace fuel for heating and heat treatment is often the largest energy line.

## Worked example: plant energy per tonne (one month)

- Electricity: 80,000 kWh x 0.710 = 56,800 kg CO2
- PNG: 30,000 SCM x 2.05 = 61,500 kg CO2
- Tonnes dispatched: 1,500
- Plant total: 118,300 / 1,500 = 78.9 kg CO2 per tonne
- Add spring steel for the full figure

Inputs are illustrative; use your own bills and production records.

## What Senseible does here

Senseible reads the plant's electricity bills (CEA grid factor 0.710 kg CO2 per kWh, CO2 Baseline Database version 21.0) and fuel invoices (IPCC 2006 defaults) into a fingerprinted Scope 1 and 2 record, the plant-level input to a per-unit figure. Bought-in materials go to the supplier evidence trail; product reports are self-declared drafts.

- [Product carbon footprint calculator](https://senseible.earth/calculators/product-carbon-footprint)
- [Forging footprint](https://senseible.earth/answers/forging-carbon-footprint-per-tonne)
- [Tractor trailer footprint](https://senseible.earth/answers/tractor-trailer-carbon-footprint-per-trailer)
- [Automobile industry](https://senseible.earth/industries/automobile)

Sources: [GHG Protocol Product Standard](https://ghgprotocol.org/standards), [ISO 14067:2018, Carbon footprint of products (iso.org)](https://www.iso.org), [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.