All about emission factors (EF)

What is an emission factor? How does it work? What are the databases that identify emission factors? We tell you everything in this article.

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When making a carbon footprint for businesses, there are several steps to follow, the first of which is data collection. In order to be able to correctly measure the GHG emissions linked to the company's activity, a common unit is needed: the emission factor.

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1. What is an emission factor?

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1.1 Definition of an emission factor

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It is a life cycle assessment (LCA) but which only takes into account the effects of global warming, i.e. an emission factor considers all the direct and indirect emissions generated throughout the life of a process, product or service. It is therefore the average emission rate from a given source, in relation to related activities, that will be expressed in CO2eq. This is what the carbon footprint measure is based on.

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1.1.1 What is the carbon dioxyde equivalent (CO2eq)?

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There are several greenhouse gases, which contribute to the intensification of the greenhouse effect, and therefore to climate change. The main GHGs are: CO2 (carbon dioxide), CH4 (methane), and N2O (nitrous oxide). The totality of human activities is responsible for increasing the concentration of these GHGs.

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The impact they have is measured thanks to global warming power : it is a unit of measurement that allows you to know how much the greenhouse effect increases by when one kilo of the gas studied is emitted, according to its lifespan in the atmosphere and its capacity to absorb infrared rays. This indicator is expressed in CO2eq, i.e. CO2 is the reference unit, with the quantities of other gases emitted being converted into the carbon dioxyde equivalent.

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1.1.2 A concrete example: the natural gas emission factor

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The energy that is the natural gas emits 0.244 kg CO2eq/kWh ICV (European average) with an uncertainty of 5%.

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It is the sum of production, transport and combustion.

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1.2 How does the calculation of an emission factor work?

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1.2.1 Taking uncertainty into account

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In the carbon accounting, some uncertainty is taken into account regarding emission factors.

Indeed, the uncertainty of an emission factor will indicate a variance in the result obtained, linked to the degree of precision possible. For example, the calculation of road freight will depend on the type of driving, the weather, and the actual filling of the truck. For the same vehicle, the carbon weight measured in tonnes/km may vary enormously. The uncertainty will therefore be high, up to 50%. Uncertainty increases with the number of parameters.

The results will necessarily be estimated but in order to reduce uncertainty in the calculations, it is advisable to use specific data such as fuel consumption rather than general data such as emissions per km for example. When collecting business data, there are two approaches that allow for different degrees of precision: the monetary approach and the physical approach.

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1.2.2 Switch to calculating GHG emissions

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In order to calculate the CO2 emissions generated when carrying out a company carbon footprint, simply multiply an activity data by the emission factor that corresponds to it and repeat the operation with all the emissions included in the Scopes 1, 2 and 3.

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2. The emission factor database developed by Sami

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Physical and monetary emission factors (EFs) are found in various databases, public and private. Each of these databases has different characteristics, with different data sets. To simplify the often time-consuming process of finding the right emission factor to associate with activity data and to gain greater precision on the greenhouse gas emissions assessments carried out by consultants (Sami consultants or consultants from partner firms) or internally by companies, we have launched a consolidated database of emissions factors.

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2.1 An unprecedented consolidated base of more than 100,000 FE

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For several years now, our teams have been developing a consolidated database of emissions factors available on our platform. Objective? To provide centralized, qualitative and as comprehensive access as possible to the emission factors from the reference databases.

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Carbon practitioners thus no longer need to “juggle” constantly between several databases, everything is grouped together in one place to facilitate their work but also to increase the accuracy of carbon footprints carried out thanks to a database bringing together a large number of EFs.

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As a result, the consolidated Sami database now provides access to more than 100,000 emission factors, from more than 25 databases (Base Empreinte®, Ecoinvent or Inies - see the details in the paragraph below).

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Our experts did not limit themselves to collecting and then grouping these EFs in a centralized database. It is a painstaking effort that has been carried out in order to validate one by one all the emission factors added to the database:

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• addition of details on the scope of the EF : cradle-to-grave (so over the entire life cycle) or cradle-to-gate (from cradle-to-grave to leaving the factory)?
• Ventilation of EFs by emission stations
• correcting the effect of inflation on monetary funds
• Cleaning up errors in source databases
• creation of common nomenclature (by country, by sector...)
• management of versioning and maintenance in real time as the various databases are updated

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This work obviously continues once the EFs are added to the Sami database with continuous updating and enrichment.

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2.2 Details of the integrated source databases

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The more than 100,000 emission factors that you will find in our consolidated database come from more than 25 reference source databases. Here are the main ones:

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Multi-criteria bases

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• The Empreinte® Base : it is the official public base in France. It now includes historical data from Base Carbone® and Base IMPACTS®. There are currently more than 10,000 EFs from the Empreinte® Base on our Sami database.
• Ecoinvent : private database, more than 21,000 emission factors. Please note, this database is only accessible if you also have an ecoinvent license.

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Sectoral bases

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• Agribalysis : public database, developed by ADEME, of more than 2500 emission factors in the agri-food sector.
• Inies : private base for the construction and building sector. Over 9000 FE.
• PCAF : more than 23,000 EF for the financial sector (real estate assets).
• EEA Passenger cars: more than 10,000 EF in the automotive sector with one detail per model and vehicle brand.
• AIB: database in the electricity sector with more than 700 emission factors.
• NegaOctet : database in the digital sector.

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Monetary ratio base

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• Exiobase : built by a consortium of European actors, more than 15,000 EFs, only monetary ratios (kgCO2e/k€).

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Geographic bases

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• DEFRA for the United Kingdom: over 5600 EFs.

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Internal source

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• Sami: more than 750 EFs from our previous carbon balances and the work of our experts and consultants.

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2.3 How do I access the FE Sami base?

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To access our consolidated FE database, you need to buy a user license. The subscription is annual. Before subscribing, you have a 10-day test phase.

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Once your subscription is validated, you access our FE database from our Sami application via a search engine that is very easy to use.

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To go further:

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• Understand everything about the carbon footprint
• The carbon footprint, an essential tool for business strategy
• The carbon footprint, a tool for economic performance

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