# What is the carbon footprint of a moulded plastic chair?

Canonical: https://senseible.earth/answers/plastic-chair-carbon-footprint-per-chair

Multiply the chair's weight in polypropylene by a resin factor, add masterbatch and fillers, then add moulding electricity per chair from your machine meter or bill. A chair weighing 2.5 kg is mostly resin; moulding usually adds a smaller share. Recycled granules lower the resin part.

## Resin and additives

- Virgin PP granules: the largest part. Use a cradle-to-gate factor per kg from the resin supplier or a recognised database.
- Recycled PP: lower per kg, but record the source and grade, since buyers will ask.
- Masterbatch, calcium carbonate filler and UV stabiliser.

## Moulding energy

- Large injection moulding machines, plus chillers and dryers.
- Runner and reject regrind returned to the hopper is not new resin; do not count it twice.
- Servo machines use noticeably less electricity than older hydraulic ones.

## Per chair

Weigh a chair off the line and divide machine electricity by chairs passed. If the same machines make tables and stools, allocate by machine hours or by kilograms moulded.

## Worked example: chair moulding per chair (one month)

- Electricity: 45,000 kWh x 0.710 = 31,950 kg CO2
- Chairs passed: 60,000
- Plant total: 31,950 / 60,000 = 0.532 kg CO2 per chair
- Add PP resin (2.5 kg per chair at your resin factor) and masterbatch 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)
- [Injection moulding footprint per kg](https://senseible.earth/answers/injection-moulding-carbon-footprint-per-kg)
- [Emission factors for PP, HDPE and PVC resin](https://senseible.earth/answers/polymer-resin-emission-factors-pp-hdpe-pvc)
- [Servo vs hydraulic moulding energy](https://senseible.earth/answers/servo-vs-hydraulic-injection-moulding-energy)

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.