Where to find emission factors, and how to pick the right ones

Explore the world of greenhouse gas (GHG) measurement with our insightful article on emission factors. Understand how these crucial numbers quantify the amount of CO2, methane, and other GHGs generated by various activities, from burning gasoline to electric vehicles.

Date Published

November 20, 2024

Author

Lucas Fraser

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Emission factors are essentially numbers that indicate how much of a particular greenhouse gas (GHG) is produced by a certain activity or process. For example, an emission factor might tell you how much CO2 is produced when you burn a gallon of gasoline, or how much methane is produced by a single cow per year.

Emission factors are important because they help us understand and track GHG emissions from different sources. By using emission factors, we can estimate how much GHG is being produced by different activities and processes, which is crucial for understanding our overall GHG emissions and figuring out how to reduce them.

Emission factors can be based on various factors, such as the type of fuel being burned, the efficiency of a process, or the type of animal or plant being grown. They're usually expressed in terms of the amount of GHG produced per unit of something else, like per gallon of gasoline burned or per flight.

Overall, emission factors are a really useful tool for understanding and tracking GHG emissions, and they're an important part of carbon accounting and GHG reporting. However, knowing where to look for the right emission factors that you can trust, and selecting the right ones for the specific activity you're measuring, can be difficult at times.

In Breeze, we use AI to recommend the best emission factor for your source based on our library of templates and trusted emission factors. Even so, it's useful to be familiar with the common publishing authorities and principles of selection to ensure you're making the right decision.

How to Select the Best Emission Factor for Your Activity Data ✔️

The best practices for emission factor selection vary based on the activity, the scope, and the calculation method—whether location-based or market-based.

Scope 1 Emission Factors

Emission factor selection for scope 1 data is straightforward. The goal is to find the emission factor that best represents the activity in question (e.g., natural gas for heating) and apply it consistently. Unless there is a specific reason not to, use the same scope 1 emission factor across your entire inventory for the same fuel. Always use the most recent emission factor available from a trusted source.

Scope 2 - Location-Based Emission Factors

When selecting a scope 2 emission factor for location-based calculations, it's best to find emission factors from a trusted authority and apply the most recently available factor.

Scope 2 - Market-Based Emission Factors

Selecting market-based emission factors for purchased energy can be challenging because the best emission factors are utility-specific. However, most utilities do not publish emission factors. In the absence of a utility-specific emission factor, use the best available residual-mix emission factor for your region from a trusted authority. If there is no utility-specific or residual-mix emission factor available, use the same emission factor as you would for the location-based emissions.

Scope 3 Emission Factors

Finding the right scope 3 emission factors can be tricky. Whenever possible, request specific emission factors from suppliers and vendors of goods and services you purchase. If unavailable, apply the same principles used for scope 1 emission factors. Seek the emission factor that best represents the activity you are measuring, from a trusted publishing authority, and use the most up-to-date factor possible.

Assessing the Credibility of Emission Factor Publishing Authorities 👓

Several factors can help you determine whether you can trust an emission factor publishing authority:

Reputation

Look for emission factor publishing authorities with a good reputation and who are widely recognized as reliable sources of information.

Transparency

Ensure the authority is transparent about its methods, data sources, and makes their data and assumptions available for review.

Peer Review

Check if the emission factors published by the authority have undergone peer review, meaning experts in the field have validated the data and methods used.

Consistency

Ensure the emission factors are consistent with other sources of similar emission factors and remain consistent over time.

By considering these factors, you can assess whether an emission factor publishing authority is reliable and trustworthy. It's important to use high-quality, reliable emission factors to ensure that your GHG emissions calculations are accurate.

Common Emission Factor Publishing Authorities 📚

Here are some popular, reliable, and trusted sources of emission factors that are available for free. These emission factors are used in the majority of corporate GHG inventories globally:

  • UK DEFRA (Department for Environment Food and Rural Affairs)
    Access them here
    DEFRA is a widely used emission factor authority, especially outside the USA. Their emission factors are reliable and regularly updated.
  • US EPA (Environmental Protection Agency)
    Access them here
    The US EPA provides a broad range of emission factors, including the best set for US grid electricity.
  • Environment and Climate Change Canada (ECCC) National Inventory Report (NIR)
    Access them here
    In Canada, ECCC provides emission factors for various fuels and industries, including regional electricity factors.
  • Australia's Department of Climate Change, Energy, the Environment and Water (DCCEEW)
    Access them here
    Australia publishes local energy emission factors, among others, via the DCCEEW's National Greenhouse Accounts Factors.
  • New Zealand Department of Environment (DOE)
    Access them here
    New Zealand provides simple emission factors for fuels, local energy use, and other common scope 1 and 3 activities.
  • Greenhouse Gas Protocol - Global Warming Potential (GWP) Values
    Access them here
    The GHG Protocol provides GWP values for various greenhouse gases, useful for converting gases to CO2e.
  • Bonus: Climatiq Data Explorer
    Access it here
    While Climatiq is not a publishing authority, it provides an easy-to-use database for emission factors for uncommon activities.

This is just a sampling of the many reliable emission factor sources available. Be sure to check with your local governments and environmental organizations for the most up-to-date information! All of these authorities publish high-quality, trusted emission factors and are included in every Breeze plan.

This is an excerpt from Section 8 of the Comprehensive Guide to Measuring Business Greenhouse Gas Emissions.

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