GHG Emission Factors: Pioneering Better Carbon Accounting Practices


GHG Emission Factors: Pioneering Better Carbon Accounting Practices

Understanding the ways to sustainable growth starts with knowing the metrics that matter.

GHG (Greenhouse Gas) Emission Factors are the foundation of a new economic paradigm centered on carbon accountability. These units allow us to measure the environmental impact (release of GHG emissions) of various activities by providing their global warming potential, providing a standardized framework for quantifying, assessing and reducing carbon footprints across emission sources. An emission factor presents the quantity of a GHG emitted to the atmosphere associated with a specific activity. 

Understanding these factors is tantamount to being able to conduct GHG inventories, track emissions and develop plans to reduce them over time.

What are GHG Emission Factors?

GHG emission factors quantify the greenhouse gases released per unit of activity, such as energy generation, transport, manufacturing or any other activity that leads to the release of GHG emissions. They are usually expressed in terms of carbon dioxide equivalent (CO2e), which factors in the potency of different greenhouse gasses relative to carbon dioxide. 

They may also be expressed in terms of the individual GHG that they represent such as N2O or CH4. When expressed at the individual GHG level, a global warming potential (GWP) is also then used to equate all individual GHGs into a single CO2e quantification. 

Infographic about GHG emission factors and their impact on greenhouse gas release.

In the energy sector, GHG emission factors play a vital role in evaluating the climate impact of different energy sources. Cleaner energy production sources such as nuclear and hydro have significantly lower emission factors compared to fossil fuels such as coal and natural gas.

Manufacturing processes heavily rely on GHG emission factors to quantify, assess and report the climate impacts of production. By analyzing emissions factors, manufacturers can identify areas where emissions can be reduced through process optimization, energy efficiency improvements, material use and the adoption of cleaner technologies.

Several factors, such as location, technology, and activity, can vary emission factors. In addition, most sources that provide emission factors are updated annually. Therefore, it is important to regularly update and refine emission factors to ensure accurate assessments of greenhouse gas emissions.

Economic sector-wise breakdown of greenhouse gas GHG contributions in the USA from 1990-2021

Navigating the intricacies of carbon accounting is simplified with North Star Carbon Management‘s cutting-edge carbon accounting software. No longer do businesses need to manually update or cross-reference emission factors. The software comes equipped with pre-integrated emission factors, eliminating the hassle of sourcing them independently. With the assurance of annual automatic updates, organizations can be confident that their data is not only current but also aligned with global standards. 

How to Use GHG Emission Factors in GHG Inventories

In GHG inventories, organizations gather data on activities like fuel consumption, electricity usage, employee commuting, purchased goods and services or product manufacturing among many other sources of emissions. This data is multiplied by corresponding emission factors to calculate the total CO2e emissions. Employing these emission factors enables businesses to pinpoint their carbon emissions accurately, highlight emission hotspots, and set baselines for gauging progress in emission reduction initiatives. 

GHG inventories aren’t just for measuring carbon emissions; they are instrumental in identifying emission-intensive areas. By evaluating the amassed data, organizations can spot high-emission activities. This intel facilitates the prioritization of emission reduction strategies. If, for instance, a manufacturer identifies a particular production process as a major emissions source, they can fine-tune this process to curtail its carbon footprint.

Calculating Source Data and Emission Factors to Get Total CO2e

To calculate the total CO2e emissions, organizations need to gather accurate source data on their activities or processes and multiply it by the corresponding emission factor the corresponding activity data has. For example, in energy accounting, organizations would collect data on energy consumption (e.g., kilowatt-hours or gallons of fuel) and multiply it by the emission factor associated with that specific energy source. The result provides an estimation of the emissions attributed to that activity.

For further details, refer to this document by Environmental Protection Agency (EPA) – Greenhouse Gas Inventory Guidance

Example of Using Emission Factors to Calculate GHG Emissions

Let’s look at using the emission factor for the stationary combustion of natural gas to calculate the GHG emissions associated with natural gas use in a building.

Data-rich table on emission factors for coal, gas, and biomass fuels from EPA

We can see that the GHG emission factors for natural gas use are the following:

  • 53.06 kg of CO2 per MMBtu of natural gas use
  • 1.0 g of CH4 per MMBtu of natural gas use
  • 0.10 g of N2O per MMBtu of natural gas use

If we wanted to quantify the emissions associated with 1,000 MMBtu of natural gas, we would calculate the following:

  • 53.06 CO2kg x 1,000 MMBtu = 53,060 CO2kg
  • 1.0 CH4g x 1,000 MMBtu = 1,000 CH4g
  • 0.10 N2Og x 1,000 MMBtu = 100 N2Og 

We now need to convert these various GHG emissions to a standard CO2 metric tons equivalent (CO2mte or CO2e mt) unit, as CO2mte is the standard reporting unit for GHG emissions globally.

Greenhouse Gas Quantities X Global Warming Potentials X Conversions = CO2 metric tons equivalent (CO2mte)

Global warming potentials come from IPCC Assessment Reports (AR):

  • Warming potential of GHG compared to CO2 over 100 years
  • May change with each IPCC Assessment report that comes out (AR4 vs AR5 vs AR6)
  • EPA continues to use AR4 

Global Warming Potential (GWP) of Key Greenhouse Gases as per IPCC 2007 Report

As EPA currently uses AR4, we will use AR4 as the global warming potential for this example.

GHG conversion formula using GWP values for CO2, CH4, and N2O.

Adding up the CO2, N2O and CH4, we get a total of: 53.1148 CO2mte

Why Emission Factors Matter in Carbon Accounting

Emission factors are the building blocks of carbon accounting as they provide a standardized and uniform way to measure emissions. Without emission factors, it would be challenging to compare emissions across different sectors, industries, or geographical regions. By using consistent emission factors, organizations can benchmark their performance against industry peers, track progress, and make informed decisions to reduce their carbon footprint.

laboratory equipment, plants, and clouds symbolizing GHG emission factors and carbon accounting.

Types of Emission Factors

Emission factors can vary depending on the specific activity, emission source, or industry sector.

Direct factors, or ‘source-specific’ factors, measure emissions from specific actions, like coal combustion in industrial settings.

Conversely, indirect, or ‘life-cycle’ factors, assess emissions throughout an item’s entire lifespan, from raw material sourcing to disposal.

For example, a car’s direct emissions originate from its fuel consumption, while its life-cycle emissions encompass everything from material mining to eventual scrapping.

For businesses committed to genuine sustainability, discerning these differences is vital, ensuring a comprehensive approach to emission reduction across all operations.

Trusted Sources

Trusted sources for emission factors range from governmental databases to international climate organizations. These sources provide comprehensive and up-to-date emission factor data that can be used as a reference for accurate emissions calculation.

An Infographic of credible institutions for providing GHG emission information

Some commonly used sources for emission factors include:

Geographical Specificity and How the Software Accounts for It

Emissions can vary across different countries and regions due to factors like energy mix, vehicle fleet composition, or industrial practices. Therefore, it is important to select emission factors that accurately reflect the geographical context in which the organization operates.

Carbon accounting software often incorporates geographical specificity by providing users with access to default emission factors based on region-specific data. Additionally, organizations can customize emission factors within the software to better align with their specific location or industry. This ensures that the emissions calculations accurately represent the organization’s impact on the environment.

Common Challenges in Using Emission Factors for Carbon Accounting

While emission factors provide a standardized approach to carbon accounting, organizations may encounter challenges in their usage. Some common challenges include:

  1. Data Accuracy: Ensuring the accuracy and completeness of source data is crucial for reliable carbon accounting. Inaccurate or incomplete data can result in faulty emission calculations.
  2. Limited Data Availability: Organizations may face challenges in obtaining relevant and up-to-date emission factors, especially for specific activities or industries.
  3. Geographical Variability: Emission factors may vary significantly across different geographic regions, and organizations need to account for this variability to ensure precise calculations.
  4. Industry-specific Factors: Certain industries may have unique emission factors that differ from general sector-wide factors. It is essential to consider such industry-specific factors to ensure accurate carbon accounting.

The Solution?

North Star Carbon Management‘s software is your answer to these challenges.

For organizations grappling with data accuracy, the software acts as a guardian, ensuring meticulousness in emission calculations.

Confronted by limited data availability? The software is ahead of the curve, always updated, ensuring that specific industry or regional factors don’t get overlooked. Geographical variability and industry-specific nuances, which once were stumbling blocks, are now seamlessly integrated.

In the dynamic landscape of energy accounting, our software stands out as a beacon, guiding businesses towards accurate, efficient, and hassle-free carbon accounting.


GHG emission factors are essential for precise carbon accounting. They allow organizations to measure, compare, and strategize emissions reduction accurately. By recognizing diverse emission factors, using reliable sources, and considering regional variations, organizations enhance their carbon accounting. Adopting specialized software like North Star Carbon Management can further refine the process and bolster reporting. Through a deep grasp of emission factors, organizations can drive sustainability and champion a greener tomorrow.

Author – Josh Prigge

Josh is a renowned sustainability professional with extensive experience in leading sustainability programs and initiatives for large organizations. His expertise is not just limited to consulting; he is also a sought-after public speaker and a college professor. To learn more about him, read about him here – About North Star Carbon Management.