How do I calculate the carbon footprint of a padlock?
Weigh the metals in each lock, such as brass, zinc alloy and steel, and multiply each by its supplier's per-kg figure. Add casting, machining, plating, assembly and packing energy, then divide the plant's energy by locks passed.
Materials
- Body: brass, zinc die cast, iron or steel by weight.
- Shackle, springs and levers in steel.
- Keys in brass or nickel silver.
Process
- Casting or forging the body, with furnace fuel.
- Machining, polishing and nickel or chrome plating.
- Assembly, testing and blister or box packing.
Per lock
Report per lock by model and size. Metal is usually the largest share, so record weights from the bill of materials.
Worked example: lock unit per piece (one month)
- Electricity: 20,000 kWh x 0.710 = 14,200 kg CO2
- LPG: 1,000 kg x 2.98 = 2,980 kg CO2
- Locks passed: 50,000
- Plant total: 17,180 / 50,000 = 0.344 kg CO2 per lock
- Add brass, zinc and 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.
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.