Do we have to use the Greenhouse Gas (GHG) Protocol's calculation tools, or can we build our own method?

The tools are optional. The GHG Protocol Corporate Standard encourages them because they are peer reviewed, but says companies may substitute their own calculation methods if these are more accurate than, or at least consistent with, its approaches. It also says to use the most accurate approach available and appropriate.

What the standard says

• Use of the tools is encouraged, as they have been peer reviewed by experts and industry leaders, are regularly updated, and are believed to be the best available.
• The tools, however, are optional. Companies may substitute their own calculation methods, provided they are more accurate than or at least consistent with the Corporate Standard's approaches.
• Companies should use the most accurate calculation approach available to them and appropriate for their reporting context.

Common approaches

• Direct measurement of emissions by monitoring concentration and flow rate is not common.
• More often, emissions are calculated on a mass balance or stoichiometric basis specific to a facility or process.
• The most common approach is documented emission factors, which relate emissions to a proxy measure of activity at a source.
• Where direct monitoring is unavailable or prohibitively expensive, accurate emission data can often be calculated from fuel use. The standard notes that even small users usually know the fuel consumed and can get carbon content through default coefficients or periodic fuel sampling.

What the tools contain

• Each tool has guidance on an overview, choosing activity data and emission factors, calculation methods, quality control, and internal reporting and documentation, plus worksheets.
• Cross-sector tools: stationary combustion, mobile combustion, hydrofluorocarbon (HFC) use in refrigeration and air conditioning, and measurement and estimation uncertainty.
• Sector tools: for example aluminium, iron and steel, cement, oil and gas, pulp and paper, and office-based organisations.
• Most companies need more than one tool. The standard's own example is an aluminium plant using the aluminium, stationary combustion, mobile combustion and HFC tools.

A test for your own spreadsheet

1. Write down the method for each source: quantity, unit, factor, factor source and year.
2. Say whether your method follows the Corporate Standard's approach, is more accurate, or is at least consistent with it. That is the standard's test.
3. Run one source both ways and keep the comparison.
4. Keep the sheet's change history, because a verifier will ask what changed and why.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records. It is not one of the GHG Protocol's own calculation tools.

• The seven steps of a GHG inventory quality system
• A data management plan for a small plant
• Which emission factor to prefer in India
• Verifier asks for calculation workings
• Free calculators

Sources: GHG Protocol Corporate Accounting and Reporting Standard (revised edition), chapter 6 (select a calculation approach, apply calculation tools), GHG Protocol Corporate Standard (ghgprotocol.org)

Last reviewed 2026-11-05. The tool list is from the revised edition of the Corporate Standard. check the GHG Protocol's tools page for the current list before you copy a method.