How does the IPCC work out cement carbon dioxide from tonnes of cement, and why not one fixed factor per tonne of cement?

Multiply tonnes of each cement type by its clinker fraction, subtract clinker imported, add clinker exported, then multiply by 0.52 tonnes of carbon dioxide (CO2) per tonne of clinker. The Intergovernmental Panel on Climate Change (IPCC) says a fixed factor per tonne of cement is not good practice.

Equation 2.1, the Tier 1 sum

1. For each cement type i, take tonnes produced times its clinker fraction.
2. Add these across types.
3. Subtract clinker imported for consumption, and add clinker exported.
4. Multiply by the clinker factor, 0.52 tonnes of CO2 per tonne of clinker, which already includes a 2 percent kiln dust correction.

Why not a fixed factor per tonne of cement

The guide says applying one cement based factor directly is not consistent with good practice because it does not account for clinker imports and exports. A tonne of cement can hold anywhere from under 30 to about 97 percent clinker, per its table.

Its footnote adds that some statistics define cement production as cement plus clinker exports. The footnote calls subtracting them good practice: if your figures are defined that way, subtract the clinker exports from the cement tonnes first, so they are not counted twice.

Where each tier gets its data

• Tier 1: cement tonnes by type, clinker fractions, clinker trade.
• Tier 2: clinker production directly, with a default or own clinker factor corrected for kiln dust.
• Tier 3: weights of each carbonate fed to the kiln and the degree of calcination, which needs plant data.

Used for one company

My reading: the same sum works for a single plant. Bought clinker comes off, because its CO2 was made at another kiln, and clinker you sell goes on. The guide writes this for national inventories, so say that in any note you attach.

One plant, three cases, 100,000 tonnes of cement at 0.80 clinker

• No trade: 100,000 x 0.80 = 80,000 tonnes of clinker x 0.52 = 41,600 tonnes of CO2
• 30,000 tonnes of clinker bought in: (80,000 minus 30,000) x 0.52 = 26,000 tonnes
• 10,000 tonnes of clinker sold on: (80,000 + 10,000) x 0.52 = 46,800 tonnes

Tonnes and the 0.80 clinker fraction are example numbers. Fuel in the kiln and power are not in this sum; they come from your invoices.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so kiln fuel and mill power are on file for each month. Clinker chemistry and cement type records stay with your plant laboratory and production log.

• CO2 per tonne of clinker
• Clinker share by cement type, IPCC table
• Grinding unit CO2 per tonne
• Free calculators

Sources: IPCC, 2006 Guidelines for National Greenhouse Gas Inventories, Volume 3, Chapter 2: Mineral Industry Emissions

Last reviewed 2026-11-05. Figures are from the 2006 IPCC Guidelines. Check whether your buyer or reporting scheme asks for a different edition of the IPCC guidance, and use your own plant measurements where you have them.