đź“ť List of emission factors
Emission factors are essential coefficients used to quantify greenhouse gas (GHG) emissions associated with various activities and processes, providing critical insights into their environmental impacts. By measuring the amount of GHG emissions generated per unit of activity, these factors enable organizations to accurately assess their carbon footprints and implement effective emission reduction strategies. Selecting appropriate emission factors involves considering their reliability, relevance, and alignment with specific activities, as well as utilizing reputable sources such as government publications and industry databases. Emission factors can be categorized into source-based and life cycle-based types, each serving different analytical purposes. Despite their importance, uncertainties in data can affect the accuracy of emissions calculations, making it vital for organizations to understand and address these limitations to foster a more sustainable future.
Emission factors are pivotal in evaluating the greenhouse gas emissions linked to diverse activities and processes. These factors signify the volume of GHG emissions generated per unit of activity, offering crucial insights into environmental impacts. By leveraging emission factors, organisations can precisely gauge and disclose their carbon footprint, enabling informed decision-making and effective emission reduction strategies.
What are emission factors?
Emission factors are coefficients that measure the quantity of greenhouse gas emissions or removals produced per unit of activity within a specific sector or from a distinct source. They are fundamental in estimating greenhouse gas inventories and play a vital role in emission calculations. For instance, in the transportation sector, fuel consumption serves as the activity data, while the mass of carbon dioxide emitted per unit of fuel consumed represents the emission factor.
How to choose appropriate Emission Factors?
To choose appropriate emission factors, several considerations need to be taken into account
- Source of emission factors: When choosing emission factors, it is crucial to consult reputable sources such as government publications, industry-specific guides, or peer-reviewed academic journals. The reliability of emission factors impacts both the accuracy of calculations and the level of confidence in the results.
- System boundary: Ensure the chosen emission factor covers the relevant scope of your activity (e.g., cradle-to-gate, cradle-to-grave). This refers to whether the EF considers all stages of a product's life cycle or just specific stages. For instance, consider the case of electricity consumption. Scope 2 emissions cover indirect emissions due to generation of consumed electricity. On the other hand, Scope 3 includes all other indirect emissions related to electricity. This includes emissions due to fuel extraction, fuel transportation, and transmission and distribution losses. Appropriately scoped emission factors will ensure accurate calculation.
- Relevance and accuracy: The emission factors should be up-to-date, ideally based on methods and data published within the last 5-10 years. Additionally, consider the global warming potential (GWP) values they are based on. Consider the specific technology or practices used in your activity, use consistent emission factors as they can impact emissions. For instance, different types of transportation vehicles or furnace technologies will have different emission profiles.
- Unit of emission factors: The unit of emission factor is pivotal in selecting the most appropriate factors as it defines how emissions are measured and interpreted within a given context. For instance, aligning emission factors with the unit of activity data is essential; if activity data is expressed in monetary terms, the emission factor should correspondingly be based on monetary units rather than physical quantities. In practice, Environmentally Extended Input-Output (EEIO) models are commonly employed to calculate emission factors in money terms.
- Supplier specific: Supplier-specific emission factors offer greater precision in evaluating greenhouse gas emissions for activities in your value chain. It enhances transparency and responsibility in the supply chain, allowing firms to report Scope 3 emissions more precisely and build credibility with stakeholders.
Where to find Emission Factors?
Multiple government agencies, industry associations, GHG programs, private companies and UN bodies publish emission factors. Some of the important sources are listed below.
List of emission factors
| Source | Description | Geography | Year | Coverage |
|---|---|---|---|---|
| ADEME | The Carbon Base, a public database managed by ADEME, offers emission factors necessary for conducting carbon accounting analyses. | Multiple regions | 2020 | Covers activity data |
| AIB | The Association of Issuing Bodies (AIB) promotes the use of a standardised system European Energy Certificate System (EECS), based on structures and procedures to ensure the reliable operation of international energy certificate systems. The work of the AIB is relevant to all electricity customers, as the Guarantee of Origin (the instrument created in the European Directive and standardised through EECS) is a cornerstone of providing reliable disclosure information on the origin of electricity supplied to consumers. | EU countries and UK | 2022 | Covers energy sector |
| AIB | The Association of Issuing Bodies (AIB) promotes the use of a standardised system European Energy Certificate System (EECS), based on structures and procedures to ensure the reliable operation of international energy certificate systems. The work of the AIB is relevant to all electricity customers, as the Guarantee of Origin (the instrument created in the European Directive and standardised through EECS) is a cornerstone of providing reliable disclosure information on the origin of electricity supplied to consumers. | EU countries and UK | 2022 | Covers energy sector |
| Carbon Border Adjustment Mechanism is a mechanism established by the European Union to impose a carbon tax on imports of certain goods from countries with less stringent climate policies. The goal of CBAM is to ensure that imported goods face similar carbon costs as those produced in the EU, thereby promoting a level playing field and encouraging global decarbonisation. | Multiple regions | 2023 | Covers iron and steel, cement, fertilisers, aluminium and hydrogen | |
| CCF | Cloud Carbon Footprint is an open source tool that provides visibility and tooling to measure, monitor and reduce your cloud carbon emissions. | Multiple regions | 2022 | Covers use phase emissions (allocated Scope 2) and embodied emissions (Scope 3) of data centres. |
| Climate TRACE | Climate TRACE is a coalition of non-profits and technology companies dedicated to accelerating the global transition to a net-zero economy. | Multiple regions | 2022 | Covers country-level emissions by sector and by greenhouse gas from 2015-2022, the applicable inventory of emissions sources, emissions source ownership, confidence and uncertainty data where available. |
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DESNZ (formerly included in BEIS) |
Conversion factors allowing organizations and individuals to calculate greenhouse gas (GHG) emissions from a range of activities, including energy use, water consumption, waste disposal, recycling and transport activities. The factors are issued by Department for Energy Security and Net Zero. | UK | 2024 | Covers across sectors. The scope of the factors is defined such that it is relevant to Streamlined Energy and Carbon Reporting (SECR) regulations of UK. |
| Ecoinvent | Econinvent’s activities include publishing and maintaining the ecoinvent database, a comprehensive life cycle inventory database that provides reliable and transparent information on the environmental impacts of various products and services. It is used by companies, researchers, and policymakers to analyze the environmental impact of their operations, make informed decisions, and develop sustainable practices. | Multiple regions | 2024 | The ecoinvent database contains more than 20,000 reliable life cycle inventory datasets, covering a range of sectors. |
| EEA | The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Its goal is to help those involved in developing, implementing and evaluating environmental policy, and to inform the general public. | Europe region | 2022 | Cross sector |
| EPA (eGRID) | The Emissions & Generation Resource Integrated Database (eGRID) is a comprehensive source of data from the U.S. Environmental Protection Agency (EPA) on the environmental characteristics of almost all electric power generated in the United States. | US | 2022 | Power generation sector |
| EPA AP-42 | AP-42, a publication by the EPA, serves as the central repository for air pollutant emissions factors from stationary sources. Established in 1972, this comprehensive compilation offers detailed information on emissions factors and processes for over 200 source categories across various industries. These emissions factors are meticulously derived through a combination of source testing, material balance analyses, and engineering estimates, ensuring accuracy and reliability. | US | 2024 | Cross sector |
| EXIOBASE | EXIOBASE is a global, detailed Multi-Regional Environmentally Extended Supply-Use Table (MR-SUT) and Input-Output Table (MR-IOT). It was developed by harmonizing and detailing supply-use tables for a large number of countries, estimating emissions and resource extractions by industry. | Multiple regions | 2020 | Cross sector |
| GHG Protocol | The GHG Protocol offers a complete suite of tools designed to assist organizations in developing robust emissions inventories. Each tool embodies best-practice methodologies that have been rigorously tested by industry experts, ensuring reliability and accuracy. Many of these tools come with accompanying PDF guidance documents, which provide step-by-step instructions for effective usage. It is important to note that most companies will need to utilize multiple tools to comprehensively cover their emissions profiles, reflecting the complexity and diversity of their operations. | Multiple regions | Last updated in 2024 | Cross sector |
| GLEC | The Global Logistics Emissions Council (GLEC) framework provides a comprehensive set of guidelines and methodologies for measuring and reporting greenhouse gas (GHG) emissions specifically within the logistics sector. Developed to enhance transparency and consistency in emissions accounting, the GLEC framework offers standardized emission factors and best practices that enable organizations to accurately assess their carbon footprints. By adopting these guidelines, companies can effectively track their emissions, identify reduction opportunities, and contribute to global sustainability efforts in the logistics industry. | Multiple regions | 2023 | Logistics sector |
| Government of Canada | The Environment and Climate Change Canada (ECCC) Data Catalogue provides a one-stop solution to describing, publishing and discovering ECCC's environmental and scientific data. | Canada | 2024 | Cross sector |
| ICE | The Inventory of Carbon and Energy (ICE) database is a comprehensive resource that provides embodied carbon factors for a wide range of building materials. Created by Dr. Craig Jones at the University of Bath while working with Professor Geoff Hammond at the Sustainable Energy Research Team (SERT), the ICE database has become a widely recognized source of embodied carbon data. With over 50,000 downloads worldwide, the ICE database is extensively used in reports, journals, books, lectures, and various embodied carbon calculators, making it a valuable tool for assessing the environmental impact of construction projects. | UK | 2019 | Construction sector |
| IEA | The International Energy Agency (IEA) Emission Factors Database is a comprehensive resource that provides emission factors for electricity and heat generation from national grids across the globe. Starting from 1971, the database covers three greenhouse gases: CO2, CH4, and N2O, for all countries worldwide. It offers emission factors per energy source, as well as average emission factors across all sources, along with additional information such as trade and losses' adjustments, and factors for direct combustion of various energy sources. | Multiple regions | 2024 | Power generation sector |
| IPCC | The IPCC Emission Factor Database (EFDB) serves as a recognized library of emission factors and other parameters that support the work of the Intergovernmental Panel on Climate Change (IPCC). While the EFDB has not undergone formal IPCC review processes, it provides users with valuable background documentation and technical references for estimating greenhouse gas emissions and removals. Users are encouraged to consult these references to ensure appropriate application of the data to their specific circumstances. | Multiple regions | 2023 | Cross sector |
| National Greenhouse Accounts (NGA) Factors | The National Greenhouse Accounts (NGA) Factors provides emission factors and methods that help companies and individuals estimate greenhouse gas emissions. These are published every year by Department of Climate Change, Energy, the Environment and Water, Government of Australia (DCCEW) | Australia | 2023 | Covers fuels, energy, waste and others |
| New Zealand’s Ministry of Environment Emissions | The New Zealand Ministry for the Environment is dedicated to facilitating climate action among organizations. In response to the increasing interest and requirements for entities across the country to measure and report their greenhouse gas emissions, the Ministry provides a set of emission factors designed to assist in this process. These emission factors enable organizations to accurately quantify their carbon footprints, empowering them to effectively manage and reduce their emissions. | New Zealand | 2023 | Cross sector |
| US EEIO | The U.S. Environmental Protection Agency (EPA) provides a comprehensive dataset of greenhouse gas (GHG) emission factors for 1,016 commodities as defined by the 2017 North American Industry Classification System (NAICS). Based on GHG data from 2019, these factors are available for all NAICS-defined commodities at the 6-digit level, excluding electricity, government, and households. The dataset includes three types of emission factors: Supply Chain Emissions without Margins (SEF), Margins of Supply Chain Emissions (MEF), and Supply Chain Emissions with Margins (SEF+MEF). | US | 2023 | Cross sector |
Source based vs life cycle emission factors
A source-based emission factor quantifies emissions directly attributed to a specific source or activity. For example, the combustion emission factor for anthracite coal, as provided by the IPCC, is expressed in kilograms per megajoule (MJ) of net calorific value. This metric represents the emissions generated when anthracite coal is burned to produce 1 MJ of energy. On the other hand, a life cycle-based emission factor considers emissions throughout the entire life cycle of a material or product, encompassing activities from raw material extraction or production to end-of-life disposal or recycling. These factors not only include direct emissions from the activity but also account for indirect emissions associated with upstream and downstream processes such as extraction, processing, transportation, and disposal.
Limitations and Considerations
Limitations in using emission factors encompass uncertainties related to both the values of emission factors and activity data. For example, when considering emission factors for a specific fuel, uncertainties can arise from a multitude of factors including variations in fuel quality, combustion technology efficiency, operational conditions, the effectiveness of control technologies in place, maintenance practices followed, and the age and condition of equipment used in the process. These variables can introduce variability in emission factor values, impacting the accuracy of emissions calculations. Addressing the uncertainties surrounding emission factors and activity data is essential to enhance the accuracy and reliability of emissions calculations.
Conclusion
Emission factors are vital for assessing and managing environmental impacts. Choosing appropriate factors from reliable sources like government publications or industry guides is crucial. Consider both source-based and life cycle-based factors based on your analysis scope. Be mindful of limitations like uncertainties in data. Understanding emission factors is key to fostering a cleaner, healthier world.