How do I calculate the carbon footprint of a glass mirror per square metre?
Multiply the float glass per square metre by its supplier figure, then add the silvering and protective coatings and the line's electricity and water heating. Divide the unit's energy by square metres of mirror made, stated by thickness.
Material
- Float glass by thickness and area.
- Silver or aluminium coating chemicals.
- Copper-free or copper backing and paint layers.
Process
- Washing and sensitising.
- Silvering and paint curing.
- Cutting, edging and packing.
Per square metre
Report per square metre by thickness. The float glass usually carries most of the footprint, the coatings far less.
Worked example: glass mirror unit per sq m (one month)
- Electricity: 30,000 kWh x 0.710 = 21,300 kg CO2
- LPG: 2,000 kg x 2.98 = 5,960 kg CO2
- Square metres dispatched: 30,000
- Plant total: 27,260 / 30,000 = 0.909 kg CO2 per sq m
- Add float glass and coatings 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.