# How do I calculate the carbon footprint of an engine piston?

Canonical: https://senseible.earth/answers/piston-carbon-footprint-per-piece

Multiply the aluminium alloy per piston, including runners and machining swarf, by the supplier's figure, then add casting, heat treatment and machining energy. Divide the plant's energy by pistons passed.

## Material

- Aluminium alloy by weight, including runners.
- Swarf returned to melting.
- Pins and rings if supplied as a set.

## Process

- Melting and gravity die casting.
- Heat treatment.
- Machining and coating.

## Per piece

Report per piston by engine type. Recycled aluminium alloy lowers the figure.

## Worked example: piston unit per piece (one month)

- Electricity: 50,000 kWh x 0.710 = 35,500 kg CO2
- PNG: 10,000 SCM x 2.05 = 20,500 kg CO2
- Pieces produced: 100,000
- Plant total: 56,000 / 100,000 = 0.560 kg CO2 per piece
- Add aluminium alloy 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)
- [Aluminium die casting footprint](https://senseible.earth/answers/aluminium-die-casting-carbon-footprint-per-kg)
- [Foundry footprint](https://senseible.earth/answers/foundry-charge-mix-pig-iron-vs-scrap-carbon)
- [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 2026-10-20.