All White Papers

How to Calculate a Carbon Footprint

What is a Carbon Footprint?

A carbon footprint, or corporate greenhouse gas (GHG) inventory, is an accounting of a company’s operational emissions. The most common GHG is carbon dioxide (CO₂), which is why greenhouse gases are often referred to as “carbon”, however there are six different GHGs that make up an organization’s carbon footprint. They are:

At the most basic level, the process of measuring a carbon footprint involves collecting a company’s full operational data and multiplying each source by an associated emissions factor to generate a relative number, or carbon dioxide equivalent (CO₂e). The full process is outlined below.

How much CO₂e is in a…

Carbon Footprint Process

The process for measuring a carbon footprint can be broken down into two phases: (1) Defining the inventory scope and (2) Quantifying the emissions. For an organization conducting its first Corporate GHG Inventory, the process can take anywhere from a few weeks to a full year. Contrary to most people’s thinking, the time investment in a carbon footprint has more to do with the quality and availability of data than the size of the organization. With the help of savvy in-house staff or a trusted, experienced consultant, the process can be shortened significantly.

Below is the 7-step process every company should follow when conducting a Corporate GHG Inventory.

Phase I: Defining

According to the primary resource for carbon footprinting, the GHG Protocol there are specific boundaries that need to be drawn around each inventory. Decisions include what locations will be surveyed, when the company will begin capturing and recording its emissions, and which emissions sources are associated with each aspect of the business.

1. Define GHG inventory parameters

• Identify your project team - include representatives from facilities management, accounting, corporate relations, and environmental management, as appropriate.
• Determine which of your organization’s locations will be included in or excluded from the inventory. There are two primary approaches used to select the organizational boundary: equity share or control (financial or operational criteria). Most companies choose to follow the operational control approach, which means that the GHG inventory will include any facility over which it has the authority to manage and implement operating policies.
• Select the most appropriate base year for the inventory, based on data availability. This does not have to be the current year and can be retroactive, but must include complete data for a full calendar or fiscal year.

2. Identify all Scope 1 (direct), Scope 2 (indirect), and Scope 3 (other indirect) emissions sources

• Each location and operational unit will have emissions sources associated with it, including electricity (kWh), fuel (gal, ccf, BTU), and refrigerants (kg, lb). It is important to carefully evaluate all emissions sources and categorize them as Scope 1 (direct), Scope 2 (indirect), or Scope 3 (other indirect). See examples below.

• Identify how data are kept for each emissions source and who is the primary owner of each data type; possible sources of emissions usage data include invoiced utility bills, travel logs, expense reports, and contracted service or maintenance records.
• Create a flow chart of data owners:

If your company’s operations extend beyond typical office space or simple manufacturing, be aware of hidden or unusual emissions sources such as SF6 at power transformers, CH4 at anaerobic wastewater treatment facilities, or other process emissions from chemical or material manufacturing.

Phase II: Quantifying

Now that the basic inventory parameters have been defined, it is time to collect data and calculate your corporate footprint.

3. Collect all source data and determine data gaps

• Collect emissions source data from identified data owners by distributing data reporting templates, through automated database downloads, or via one-on-one communication. This is frequently the most time-consuming part of a GHG inventory, so be sure to schedule accordingly.
• Assemble the data for each emissions source by month or invoice period, facility type, and location type to determine whether there are areas where key information is missing. Missing information is an expected outcome, especially when undergoing the inventory exercise for the first time.

4. Estimate and model any missing data

• If there are information gaps after uploading a database, try to fill in data by going back to source documents (e.g. invoices), making a second request of data holders, and checking for additional data sources.
• Develop a modeling approach for missing data that is based upon existing corporate or industry data sets. For example, the Commercial Buildings Energy Consumption Survey provides average utility usage estimates by square foot for office space. Company-specific models can also be developed using samples of data from similar emissions sources.
• Produce a complete set of usage data for each emissions source.

5. Conduct quality assurance procedures

• Review each emissions source for accuracy by spot checking manually entered data against original records, plotting categories of data to locate outliers, identifying duplicate values, and assessing unexpected seasonal data trends.
• Usage data should also be benchmarked against internal or external data norms as appropriate (e.g., average kWh consumption per square foot of office space).
• Combine all collected and modeled information into a centralized database sorted by emissions source.
• Standardize data for dates, facility identifiers, location information, North American Electric Reliability Corporation (NERC) regions, and other key characteristics. Following integration, conduct an additional quality assurance review to ensure that information was properly migrated from source files and that no inaccuracies were introduced. See example of an electricity data spreadsheet below.

6. Calculate GHG emissions

• Collect all relevant unit conversion factors and emissions factors for storage in the emissions inventory database. A list of resources for emissions factors and calculating tools including the U.S. EPA (Climate Leaders, eGrid, etc.), Intergovernmental Panel on Climate Change (IPCC), and World Resources Institute (WRI) is available at the bottom of this document.
• As a general rule of thumb, a quantity of consumption (fuel, electricity, etc.) is multiplied by source-specific factors in order to obtain the emissions of each greenhouse gas. For example, stationary and mobile combustion emissions factors for diesel fuel vary depending on the use of that fuel.
• Convert the consumption quantities for each source to a common unit that is compatible with the emissions factors available (e.g., kg CO2 per BTU of natural gas).
• Following conversion, multiply the identified emissions factors by the quanity of consumption to calculate total emissions for each of the six GHGs.
• Apply global warming potentials to the non-carbon dioxide gases to convert them to carbon dioxide equivalents (CO2e). The result of this process is a full set of GHG emissions by emissions type, fuel type, and emissions source. The figure below shows how initial usage data are manipulated to arrive at the final corporate inventory.

Sample Calculation:

• Facility A used 100,000 kWh in 2008
• Facility A is located in Richmond, VA

7. Create an Inventory Management Plan and Summarize Results

• Determine reporting needs: internal, external, voluntary registries, retailer questionnaire, etc.
• Create an Inventory Management Plan (IMP) to document and institutionalize the GHG inventory process. Use available resources to ensure your IMP includes all relevant information. The U.S. EPA Climate Leaders and The Climate Registry both provide guidance:
  • U.S. EPA Climate Leaders: Inventory Management Plan Checklist
  • The Climate Registry: Inventory Management Plan
• Use your database to report emissions data at varying levels of granularity and in various formats.
• The completed inventory database will serve as a benchmark tool and may need to be updated if your company downsizes or acquires new facilities. It is an extremely effective way to understand how your company is spending money on energy, fuel, and resources, and will provide transparency into your carbon risks.

The final product is a complete carbon footprint of your corporate emissions that can be shared with customers, like Wal-Mart, will support voluntary reporting, shows where you stand in the emerging carbon market, and serves as a benchmark for current and future carbon management efforts. A well-constructed GHG inventory will not only provide insight into the sources and magnitudes of emissions, but will also clearly associate emissions, energy use and financial information. You can use these findings to see where your organization is overspending on energy and look for reduction opportunities. Going forward, an annual carbon footprint will help you measure the progress of your climate change strategy against your baseline emissions.

To learn more about the process of calculating a carbon footprint submit a question to info@clearcarboninc.com.