How do I report a reduction, or an increase, in a product carbon footprint under the Greenhouse Gas Protocol Product Standard?

Under the Greenhouse Gas (GHG) Protocol Product Standard, the reduction percentage is the base inventory minus the new inventory, divided by the base inventory, per unit of analysis. An increase should be reported as an increase, with an explanation, and a minus sign should not be used.

The calculation

Take the difference between the base inventory and the new inventory and divide it by the base inventory. The result is on the unit of analysis basis, for example per piece or per tonne, so a change in volume sold does not change it.

What counts as a reduction: the standard says reductions should be assessed using direct measurement data, activity data or emission factors that follow its attributional approach, meaning historical, fact-based and measurable, and that happened before the updated inventory.

If the footprint went up

The standard says an increase should be reported with a clear indication that it is an increase, not a reduction, and that a minus sign should not be used because it may confuse readers. It adds that the company should explain why emissions rose and what it plans to do about it.

What a company that reports a target or tracks change shall report

• The base inventory and current inventory results in the updated report.
• The reduction target, if one was set.
• Changes made to the inventory, if the base inventory was recalculated.
• The threshold used to decide when recalculation is needed.
• Context for significant changes that triggered recalculation.
• The percentage change between the two inventories on the unit of analysis basis.
• An explanation of the steps taken to reduce emissions.

Also say how many reports there have been

The standard says the number of updated inventory reports for the product should be reported, with a link to earlier ones where available.

A component maker's footprint per piece (example numbers)

• Base inventory: 4.20 kilograms of carbon dioxide equivalent (CO2e) per piece
• New inventory: 3.78 kilograms. Change: (4.20 minus 3.78) / 4.20 = 10%, reported as a 10% reduction
• If the new figure were 4.41: (4.41 minus 4.20) / 4.20 = 5%, reported as a 5% increase, with the reason, and not as minus 5%

Per piece figures are example numbers.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the fuel and power used each month are on file to compare year on year. The unit of analysis and the product's own method are yours to define.

• How Senseible checks records
• Changed product unit: new base inventory
• Product footprint target and offsets

Sources: GHG Protocol Product Life Cycle Accounting and Reporting Standard, chapters 13 and 14

Last reviewed 2026-11-04. Wording is from the 2011 Product Standard. A buyer or programme may ask for a different format.