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Understanding emission factors: A key to carbon accounting

Emission factors are foundational tools in the world of carbon accounting. They play a pivotal role in quantifying greenhouse gas (GHG) emissions and understanding the environmental impact of various activities, processes or products. In turn, they help to empower organisations and policymakers to make informed decisions regarding emission reduction strategies.

In this article, we delve into what emission factors are, how they are determined and why they play a crucial role in accurate carbon accounting.

Where do emission factors fit into carbon accounting?

Let’s quickly recap on the steps of carbon accounting to remind ourselves of how emission factors fit into the process.

  1. Define your scope and identify emission sources: Begin by defining the scope of your carbon accounting initiative. This involves determining what activities, processes and emissions sources you want to include.

  2. Choose an accounting standard: Select a carbon accounting standard that aligns with your organisation's goals and resources. Common standards include the Greenhouse Gas Protocol and ISO 14064.

  3. Carbon accounting tools and software: Invest in carbon accounting tools or software that streamline the process. These tools automate data collection, emissions calculations and reporting.

  4. Data collection: Collect relevant information pertaining to energy consumption, fuel usage, transportation and any other activities contributing to emissions within your boundaries.

  5. Identify emission factors: Emission factors are coefficients that quantify the amount of GHGs produced per unit of activity, energy or spending. Refer to reliable sources like government databases, industry standards or recognised emission factor databases, which we will highlight in more detail later on.

  6. Perform the calculations: Apply the chosen methodology and emission factors to the corresponding data to calculate emissions accurately. Ensure units are consistent and conversions are made where necessary.

  7. Establish baseline emissions: Create a baseline of your organisation's emissions to serve as a starting point for future comparisons. This baseline will be invaluable for tracking progress and evaluating the effectiveness of your emission reduction initiatives.

  8. Monitor and report: Transparent carbon reporting builds trust with stakeholders, both internal and external, and demonstrates your commitment to decarbonisation. This means that it is important to continuously monitor your emissions data, track progress against your baseline and regularly report your findings.

  9. Integrate emissions calculations into decision-making: Incorporate emissions data into decision-making processes. Use it to set sustainability targets, evaluate the environmental impact of different strategies and enhance overall sustainability performance.

Emission calculations

What are emission factors?

An emission factor is a numerical value representing the amount of a GHG, such as carbon dioxide (CO2), methane (CH4), or nitrous oxide (N2O), released per unit of a specific activity, process or fuel consumption.

Essentially, it indicates the emissions associated with a given unit of input or output in a standardised and measurable manner.

Emission factors are typically expressed in terms of weight (e.g., kilograms or metric tons) of emissions per unit of activity (e.g., kilometres travelled, energy consumed, products manufactured) or fuel consumed.

The process of determining emission factors involves comprehensive scientific research, data analysis and often extensive testing.

Key steps include:

  1. Data collection and analysis: Researchers collect data on emissions and the associated activities or processes. This could involve on-site measurements, laboratory studies or analysis of historical data.

  2. Normalisation: The collected raw data is then normalised or standardised to a consistent unit of measurement, ensuring comparability.

  3. Calculation: Emission factors are calculated by dividing the total emissions by the total activity or fuel consumption. For example, the emissions from a car trip might be divided by the distance travelled to determine the emission factor for that specific trip.

  4. Verification: Emission factors are rigorously reviewed and verified by experts in the field to ensure their accuracy and reliability.

Emission factor sources

Utilising reputable sources and staying updated with the latest developments ensures the accuracy and reliability of emission factors, supporting informed decision-making and sustainable practices. It’s important to verify the credibility and applicability of the emission factors based on your specific industry, region or activity for high-quality carbon accounting.

Let's explore some primary sources of emission factors:

Government environmental agencies

National or regional environmental agencies often compile and publish emission factors tailored to their specific jurisdictions. For instance:

International Organisations

Organisations working on global sustainability compile emission factors to aid countries in GHG inventory reporting and mitigation strategies. For example:

Industry associations

Associations related to specific industries often develop and publish emission factors based on their research and expertise.

In addition, utility companies often provide emission factors related to energy production and consumption.

Research papers and journals

Academic and scientific research often leads to the development of new or improved emission factors. Peer-reviewed journals and research papers are valuable sources for the latest advancements.

Similarly, universities and academic research centers often conduct research leading to the development of emission factors. Collaborations with industry and government bodies enhance the credibility and relevance of these factors.

Mitigating emission factor challenges

Knowing how to source the best emission factors and use them properly is not always easy. Common challenges include locating emission factors due to their dispersion across various sources and formats, or staying up-to-date with the most relevant emission factors as they evolve with new research and technologies.

Here are some tips to help you overcome these obstacles and follow best practice:

  • Explore carbon accounting software: Utilise carbon accounting software that integrates updated and validated emission factors. These platforms provide a wide range of emission factors for different activities and industries, which are regularly updated in line with the latest research.

  • Use credible sources: Rely on reputable sources, such as the ones mentioned above. These organisations often conduct rigorous research and provide updated, and often more accurate, emission factors.

  • Check relevance and applicability: Ensure that the emission factors are relevant to your industry, region and specific operations. Factors can vary significantly based on technologies, fuels, equipment and regional characteristics.

  • Look for industry-specific factors: Industry associations often publish emission factors specific to their sector. These factors may be more accurate for your industry's unique processes and activities.

  • Consider geographic variations: Emission factors can vary by region due to differences in energy mixes, technologies and regulatory standards. Use factors specific to your geographical location whenever possible.

  • Check data relevance: Emission factors can change over time due to technological advancements or new research. Always verify the publication date to ensure you're using the most current data.

  • Check pollutants modelled: Different emission factors are available for various pollutants, like different GHGs. Make sure to choose factors based on the pollutants you are tracking.

  • Regularly update emission factors: Stay informed about updates in emission factors through subscriptions to relevant newsletters, websites or publications. Update your database regularly to reflect the latest factors.

Reach out to our team to learn more about how our carbon accounting software significantly enhances the accuracy, efficiency and relevance of emission factor usage in footprinting calculations.


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