Understanding Scope 1 Emissions

Sumday Team
October 2, 2023
3 minutes

Understanding Scope 1 Emissions

In the context of carbon accounting, Scope 1 emissions refer to direct emissions that result from sources owned or controlled by a company, as defined in the The Greenhouse Gas Protocol, a widely respected set of standards for carbon accounting (Need a recap? Visit What is the GHG protocol for a quick overview).

So, what do ‘direct emissions’ look like?

Scope 1 includes direct emissions from sources owned or operated by the company, but what exactly does this look like? The GHG Protocol guidelines have categorised Scope 1 emissions into four main categories, let’s take a look at each one.

Mobile Combustion

Emissions resulting from the combustion of fuels in company owned/controlled combustion sources (e.g., trucks, ships, cars, planes, for both passenger and freight transportation.)

Mobile combustion refers to the burning of fuels in the transportation of mobile (moving) devices such as cars, trucks, buses, trains, airplanes, ships, etc. Essentially, anything that moves due to the burning of fuels needs to be accounted for in mobile combustion emissions as long as the assets are owned or controlled by the business. As a fuel source is consumed, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are released directly through the combustion process.

In Sumday, to calculate these emissions, you're creating a worksheet for each asset (like your fleet vehicles) and inserting the litres of fuel consumed, the fuel type and location. Scope 1 emissions are pretty straightforward for most businesses.

Some common mobile sources are shown in the table below:

Stationary Combustion

Emissions resulting from the combustion of fuels in stationary sources, often to generate heat, electricity or steam (e.g., boilers, LPG burners such as a BBQ, diesel generator)

Stationary Combustion involves the combustion of fuels that produce emissions including carbon dioxide, methane and nitrous oxide. Stationary combustion is not to be confused with mobile combustion, which involves combustion from assets that move – instead, as the name implies, this is combustion of fuels for non-moving, stationary objects.

For example, companies may have commercial kitchens using liquid petroleum gas (LPG) as the heat source. As LPG burns, it releases carbon dioxide and trace amounts of methane and nitrous oxide, with each litre of LPG used equating to around 1.56 kg of CO2e.

Fugitive Emissions

Emissions resulting from the intentional or unintentional releases of GHGs during the extraction, production, processing, storage, disposal, transport, or use of fossil fuels. (e.g., leaks from fridges, air conditioning units, coal mines, vents)

Fugitive emissions refer to the direct release of GHGs from equipment and processes. Common sources include refrigeration and air conditioning systems, fire suppression systems, and the release of industrial gases. The release of GHGs can happen during the manufacturing process, leak during equipment operation, or when disposed of at the end of the equipment's operating life. Many people are surprised, but if you think about refrigerants that are used in fridges to keep them cool, overtime as the refrigerant cycles through transitioning between liquid to gas and back again, some of that gas will leak and result in GHGs being released into the atmosphere unintentionally.

Historically, substances that were harmful to the ozone layer, like chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), were commonly used in air conditioning and refrigeration equipment. These substances have been phased out and replaced with hydrofluorocarbons (HFCs) and, to a lesser extent, perfluorocarbons (PFCs). Although HFCs and PFCs aren’t as directly harmful to the ozone layer since it doesn’t release chlorine compounds, these gases still have a significantly higher global warming potential (GWP) compared to carbon dioxide. They can range from 140 to 11,700 times higher, so their potential impact on climate change can be very significant… hence why it’s important to measure it! And as such, any reductions of these gases can be a large win for the planet too!

Process or Chemical Emissions

Emissions resulting from the manufacturing or processing of chemicals and materials (e.g., cement, aluminium, adipic acid, ammonia, waste processing)

Process or chemical emissions occur during the chemical transformation of raw materials, such as the production of nitrous oxide (N2O) during the production of nitric acid or adipic acid. Cement production is also a prime example of this, specifically wherein the calcination process occurs. Chemically, the calcination process looks like this:

CaCO3 -> CaO + CO2

And you guessed it, that CO2 formed as a by-product of the calcination process is often emitted into the atmosphere!

Not all businesses will have process or chemical emissions, these emissions are typically only relevant to specific industry sectors such as oil and gas, aluminium, and cement. Appendix D on page 92 of the GHG Protocol’s Corporate Standard provides a handy table of the various emission sources by industry sector, we suggest having a read as this can be used as a great starting guide to identify a business’ emission sources. Other accounting standards and frameworks also have sector specific guidance including the Climate Disclosure Project (CDP) which are beneficial to be aware of as either you or your client starts their carbon accounting journey. 

The wrap up on Scope 1 emissions

Many businesses have processes and operations that involve one or more of the above activities, and as a result, produce these direct Scope 1 emissions that need to be accounted for. By accurately measuring their Scope 1 emissions businesses can gain insights into their direct environmental impact and develop strategies to mitigate and reduce these emissions!

Interested to learn more about Scope 1 emissions and other aspects of carbon accounting? There’s a whole chapter on this in the Introduction to Carbon Accounting course, check out the Sumday Academy for free when you start a trial.