What are emission factors and where do they come from?

An emission factor is a standardised value that shows how much climate impact a specific activity, product or service causes. It links something measurable, such as kilowatt hours, litres of diesel or kronor spent on office supplies, to an emissions value in carbon dioxide equivalents (CO₂e). Without emission factors, it would be impossible to calculate a company's carbon footprint at any reasonable scale.

Want to skip hunting for emission factors yourself and stop wrestling with spreadsheets? See how GoClimate does the maths for you.

Where do emission factors come from?

Emission factors are based on research, national emissions statistics and scientific databases. In Sweden, the Swedish Environmental Protection Agency (Naturvårdsverket) publishes average emission factors every year for fuels and other sources, which companies can use to calculate their direct emissions¹. Internationally, the US EPA's Emission Factors Hub is one common source².

Greenhouse gas emissions aren't just about carbon dioxide. Emission factors also cover other greenhouse gases such as methane, nitrous oxide and fluorinated gases. The gases warm the climate by different amounts, so they're all converted into a common unit: carbon dioxide equivalents. One kilo of methane has a much bigger warming effect than one kilo of carbon dioxide, which is why each gas has its own conversion factor. A key part of the work is keeping the factors up to date as the energy mix changes and new research emerges.

GoClimate develops and maintains its own emission factors. They're based on established national and international data sources and tailored to the industries and purchasing categories most common among Swedish companies. That means the emission factors behind your carbon footprint in GoClimate's tool are built for Swedish conditions, not generic global averages.

Why emissions in other countries matter

A large share of the climate impact from what we buy doesn't happen in Sweden at all. It happens in the countries where the goods are made. Sweden's consumption-based emissions are the emissions linked to our consumption, wherever they occur. In 2023 they totalled around 80 million tonnes of CO₂e, or 7.6 tonnes per person. As much as 64 per cent of them occurred abroad³. Roughly 60 per cent come from household consumption, and the rest from public consumption and investments⁴.

For a company, this means the biggest emissions often sit with its suppliers, in their production. And that's exactly where emission factors are needed to make those emissions visible at all.

Two types of emission factors: activity-based and spend-based

There are basically two types of emission factors, depending on what data you start from.

Activity-based emission factors start from what actually happened physically: how many litres of diesel were filled, how many kilowatt hours of electricity were used, or how many tonne-kilometres of goods were transported. The emission factor gives the climate impact per physical unit, for example kg CO₂e per litre of diesel or per kWh. The method is highly accurate but requires detailed data for every purchase. That quickly becomes very time-consuming without a service like GoClimate's. The same data can also be used in a life cycle assessment (LCA) to calculate environmental impact across a product's entire life cycle, from raw material extraction to waste.

Spend-based emission factors start from the money: how much did we pay, and to what type of supplier? The emission factor is expressed in kg CO₂e per krona spent and is then multiplied by the amount. The problem is that it relies on industry averages. Emission factors can vary widely depending on research methods, regions and production processes. An average tells you nothing about how your particular supplier makes its products or what production lies behind them. In one example from ClimatePartner, the spend-based method overestimated emissions from purchased services by 37 per cent compared with activity data⁵.

Put simply: activity-based emission factors measure what physically happened. Spend-based factors start from what it cost and work backwards from there.

GoClimate primarily uses activity data in its automated calculations. Read more here!

How are emission factors used in practice?

The GHG Protocol, the standard most climate frameworks are built on, ranks four calculation methods for purchased goods and services. Supplier-specific data comes first, then hybrid methods, followed by average activity-based and spend-based emission factors.

In practice, many companies use activity-based and spend-based methods side by side, because different emissions call for different data. Direct emissions from company vehicles and premises are calculated with activity-based emission factors, while purchased goods and services are often calculated with spend-based ones. Business travel, in turn, can be calculated from distance travelled and mode of transport. Together, they give a comprehensive picture of your emissions.

GoClimate automatically matches every invoice to the right emission factor.

Why does the difference matter?

An emission factor is never exact. It's a well-founded estimate, often based on average data. If you buy office furniture for SEK 50,000, you get the same spend-based factor whether the supplier uses recycled materials or not. So a product's actual climate impact may differ from what average-based factors show. (Electricity has its own rules, by the way: there you can use your actual electricity contract, for example if you buy certified wind power⁸.)

That's why emission factors vary in precision. Supplier-specific emission factors, where the supplier shares its actual climate data, give the highest accuracy and the lowest uncertainty. Average emission factors are less precise, but they cover the entire value chain without you having to talk to every single supplier. Which part of the chain to prioritise depends on where your company's emissions are largest.

As climate reporting matures and more suppliers share their climate data, calculations can be refined with more accurate primary data. But the foundation stays the same: systematically linking activities and purchases to emissions using standardised emission factors.

Emission factors as a starting point

There's no such thing as a "perfect" emission factor. But there's a big difference between not measuring at all and starting with the data you already have.

Emission factors aren't the finish line. They're the starting point. They answer the fundamental question: what's causing our emissions, and where can we cut the most? From there, more targeted action can follow, with better data, closer supplier dialogue and, over time, activity-based emission factors for the most important categories. Sweden is also turning its attention to consumption: the Swedish Environmental Objectives Committee (Miljömålsberedningen) has proposed that Sweden's consumption-based emissions reach net zero by 2045, including emissions that occur in other countries⁹. The sooner you start measuring, the better.

Curious where your company stands today? Do your first calculation with GoClimate.

Want to see which emission factors calculate your company's climate impact?

GoClimate's tool automatically matches your purchases to the right emission factors and calculates your emissions, with no manual work. Try GoClimate here!