What is the carbon footprint of a moulded plastic 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
• Injection moulding footprint per kg
• Emission factors for PP, HDPE and PVC resin
• Servo vs hydraulic moulding energy

Sources: GHG Protocol Product Standard, ISO 14067:2018, Carbon footprint of products (iso.org), IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults), CEA CO2 Baseline Database, version 21.0

Last reviewed 2026-10-20.