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Get started: the GHG formula

How to collect data and calculate your company GHG footprint

After identification of the GHG emissions to be accounted for, the next step is to collect the data necessary to compute the calculation below.

The data collection step is crucial but also one of the most challenging for companies and often involves dealing with a large amount of data and stakeholders. It is important that the data sources and assumptions are tracked and recorded as they will be needed for verification and for the next inventory cycle. It is possible that, in the first year of GHG accounting, the data will have a low level of granularity. However, your company should aim to refine and improve this data over time.

This section defines best practice and practical recommendations for data collection, including how to consolidate and analyze GHG emissions data.

If your company is undertaking a specific certification, it may need to comply with specific requirements. For more information on certifications, please refer to Step 3.

1. The GHG emissions formula

  • Activity data:

​Activity rate or consumption amount is the total amount of the product or service consumed/used. Typical units are the amount consumed or used (e.g., liters, kg, gallons, sq. ft.) or the amount spent (e.g., $).

​Example: A construction company purchases 30 liters of Diesel as raw materials: 30 liters is the activity data.

  • Emission factor:

Emission factors are ​the average amount of greenhouse gases emitted per unit of consumption or use. Typical units are weight (e.g., tons, kg) of CO2e per unit of consumption.

Example: The emission factor for diesel is 2.7 kg CO2e per liter of Diesel.

  • GHG emissions:

​The GHG emissions emitted directly or indirectly from the consumption or use of the product or service. Typical units are weight (e.g., tons, kg) of CO2 equivalent (CO2e).

Example: 80 kg CO2e is emitted in combusting the given amount of diesel.

Illustrative calculation: