What default carbon dioxide factor and cullet share does the Intergovernmental Panel on Climate Change give for each type of glass?
The Intergovernmental Panel on Climate Change (IPCC) gives 0.21 kilograms of carbon dioxide (CO2) per kilogram of glass for float and container glass, 0.19 for E-glass fibre, 0.10 for tableware and 0.03 for lab or pharma glass. Multiply by one minus the cullet ratio.
Default factor and typical cullet range, by glass type
- Float: 0.21, cullet 10 to 25%.
- Container, flint: 0.21, cullet 30 to 60%. Container, amber or green: 0.21, 30 to 80%.
- Fibreglass, E-glass: 0.19, 0 to 15%. Fibreglass insulation: 0.25, 10 to 50%.
- Tableware: 0.10, 20 to 60%. Lab or pharma: 0.03, 30 to 75%. Lighting: 0.20, 40 to 70%.
- The factors are kilograms of CO2 per kilogram of glass. The guide also lists television panel and funnel glass.
How to use the table
Tier 2: CO2 = mass of glass melted x factor x (1 minus cullet ratio), for each glass type. The mass is glass melted, not glass sold. The guide says to use the mid-point of the range unless you know a better value, and cullet ratios vary a lot between plants, so use yours if you have it.
These factors cover the carbonates in the batch only. Furnace fuel and electricity are separate lines.
The quick default behind it
A typical soda-lime batch is sand 56.2%, feldspar 5.3%, dolomite 9.8%, limestone 8.6% and soda ash 20.0%. A tonne of raw materials gives about 0.84 tonnes of glass and loses 16.7% as volatiles, virtually all CO2: 0.167 / 0.84 = 0.20. At a default cullet ratio of 50%, that is 0.20 x 0.50 = 0.10 tonnes of CO2 per tonne of glass.
How far to trust each tier
- Tier 3, from carbonates fed: factor uncertainty 1 to 3%.
- Tier 2: about plus or minus 10% on the factor, and the cullet range is treated as a 95% confidence interval.
- Tier 1: on the order of plus or minus 60%.
- If you keep batch house records, Tier 3 is the better route.
A flint container furnace melting 3,000 tonnes in a month
- Mid-point cullet 45%: 3,000 x 0.21 x 0.55 = 346.5 tonnes of CO2
- At the low end of the range, 30% cullet: 3,000 x 0.21 x 0.70 = 441 tonnes
- At the high end, 60% cullet: 3,000 x 0.21 x 0.40 = 252 tonnes
- So your real cullet share matters more than the glass type
3,000 tonnes is an example. Process CO2 only; add furnace fuel and electricity.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so furnace fuel and site electricity are on file. Batch weights and the cullet share come from your batch house records.
- Carbon calculators
- Glass container furnace: CO2 per tonne
- Cullet and CO2 saving
- Firozabad glass batch carbonates
Last reviewed 2026-11-04. The 2006 Guidelines are written for national inventories. A plant's own lab assay, production log and fuel invoices replace these defaults wherever you have them.