What are Emission Factors?

Updated

Emission factors are the conversion numbers that let you estimate carbon emissions using the business data you already have - like spend, fuel use or electricity consumption. They represent the average greenhouse gas (GHG) emissions associated with a specific activity, product, or service.

In other words, an emission factor tells you how much carbon is typically released per unit of something — like dollars spent on a good or service, litres of fuel used or kWhs consumed.

💡 Examples:

  • $20,000 on repairs and maintenance × emissions factor = 100 tonnes CO₂-e

  • 1,000 kWh of electricity × emissions factor = 170 kg CO₂-e

They’re sometimes called conversion factors, emissions intensity, or carbon intensity — and they’re a foundational building block of carbon accounting.

Emission Factors are found in EF Databases. These are often provided by the government or academic organisations. There is not right or wrong database to use, and often no right or wrong single EF to choose. The key is to be transparent on where they come from (Sumday handles that for you) and ideally be consistent year on year on what ones you choose, unless you have a good reason for not following that path. 

Most databases are based on:

  • Economic models and supply chain data

  • Government and academic research

  • Peer-reviewed studies

These aren’t your supplier’s actual emissions — they’re industry-wide averages. While imperfect, they’re globally accepted for carbon accounting, especially when real data isn’t available.

Sumday makes it easier to improve over time by collecting data directly from your suppliers.

 

🤔 How to use Emission Factors in Sumday

If you're feeling a bit overwhelmed, you're not alone — even experienced carbon accountants worry about what to choose.

Creating an Assessment

Here’s what we recommend:

  • Start with Sumday’s default databases — selected based on your geographic location and built from public, reputable sources (these are already selected when you create an assessment). You can always add more later if you need to.

  • Don’t stress about a “right” choice — emission factors are averages used globally. They’re good enough to start measuring, and Sumday helps you improve accuracy over time. 

  • You can upload your own factors if needed. 

In the Carbon Ledger

One of the key jobs to do is to allocate an Emission Factor to your spend transactions in the Carbon Ledger. AI will provide a smart suggestion based on your transaction data and the EF databases you have chosen. You can then choose a different EF from the available databases in the drop down menu in the right hand tray as you need. 

Common Problem: Stressing about what EF to use, for example is it "bread" or "sourdough" - unfortunately, the trouble with averages is that stressing over this is not worth your time. Pick one and be consistent (Sumday remembers what you chose last time too). The better way to spend your time is on getting the actual emissions from your bread provided with supply chain engagement. 

In the Scope 3 Tables

You will also select EFs in the scope 3 tables when you use activity data. Search for the available EFs (smart suggestions coming here soon). 

 

🌱 What Are Sumday’s Default Emission Factors?

Sumday applies a default set of emissions factors based on your organisation’s location.

These are selected for:

  • Public availability

  • Transparency

  • Regional alignment

Default databases include:

 
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