Activity Data & Emission Factors

Activity Data

When calculating an organization's greenhouse gas inventory, footprint activity data is gathered across the organization and its value chain.

Activity data is a quantitative measure of an activity an organization engages in that results in the emission of greenhouse gasses.

Some examples include:

• 10 gallons of diesel fuel used by a generator
• 1,000 kWh of electricity consumed at a facility
• 200 miles traveled for business on an airplane
  

For each activity, the source of the data must be identified. For instance — will the data come from a utility bill or will it come from a meter on-site? The footprint source or type of activity data will affect the accuracy of the emissions calculation.

Emission Factors

To begin the process of calculating an emissions estimate, each unit of activity data must be converted into the quantity of GHG emitted as a result of that activity.

Oftentimes, a single activity type can produce more than one type of greenhouse gas.

The combustion of natural gas typically produces carbon dioxide, methane, and nitrous oxide.

An emission factor is a factor that converts activity data — like the combustion of natural gas — into greenhouse gas emissions data.

Some examples of emission factors are shown:

• lbs CO₂/mi: Pounds of carbon dioxide per mile of vehicle traveled
• ton CH₄/Btu: Short tons of methane per British thermal unit of natural gas
• g N₂O/L: Grams of nitrous oxide per liter of propane