What is a carbon footprint?

What Is a Carbon Footprint?

You’ve almost certainly heard the term “carbon footprint” – popularised by, of all people, British Petroleum in 2005 – but what does it actually mean?

At its core, a carbon footprint is simply the total amount of greenhouse gas emissions that result from just about anything, whether it’s you boiling a kettle, a business shipping goods halfway around the world, or the plane trip you took to Marbella.

Understanding your carbon footprint—or that of a business, a product, or even your pet cat—is important because it helps pinpoint the environmental impact of various activities and, crucially, where you might want to cut back to save the planet (or at least do your bit).

So, let’s dive into what a carbon footprint really means and how this all gets calculated.

What Is a Carbon Footprint For a Business?

For businesses, the term "carbon footprint" refers to the total amount of greenhouse gases you emit as a result of your business activity.

This covers a wide range of things: heating the office, powering your laptops, flying executives to conferences – and many, many more (we’ll go into detail later).

While you can calculate the carbon footprint of a specific product or service, most businesses start by calculating the carbon footprint of their organisation as a whole: all the emissions resulting from their own operations, their supply chain, their employees, and even their customers.

What is the GHG Protocol?

The Greenhouse Gas (GHG) Protocol is the most widely used international tool for businesses to complete a carbon footprint. Think of it as the rulebook for counting carbon, developed by the boffins at the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD).

In short, the GHG Protocol makes sure everyone is singing from the same carbon-counting hymn sheet. It provides a comprehensive framework that helps businesses and other organizations measure and manage their greenhouse gas emissions in a way that’s consistent, transparent, and, crucially, makes sense to others.

Its most widely used document is the Corporate Accounting and Reporting Standard, which governs how to measure the emissions of an entire business. It also produces more focused standards for measuring the emissions from specific projects and product lifecycles.

If you’re ever asked for your footprint by a regulator, or in a client tender, it’s almost certain that you’ll need to comply with the GHG Protocol in how you measure and report that data.

What is included in a GHG Protocol Compliant footprint?

If you’re going to be GHG Protocol-compliant (and why wouldn’t you be?), you’ll need to include emissions from three main categories, or "Scopes" as they're known to the initiated:

• Scope 1: These are the emissions that come directly from things you own or control, like the fumes from your company vans or the boilers in your buildings.
• Scope 2: This covers the emissions from generating the electricity, heat, or steam that you buy and use. You didn’t burn the coal, but you did use the electricity.
• Scope 3: This includes all the emissions that are a result of your business activities but occur elsewhere in the value chain – everything from the products you buy to how your employees commute to work.

By covering all three scopes, the GHG Protocol ensures that you’re getting the full picture of your company’s impact on the climate—no loopholes here! Our next lesson goes into the detail here.

What Does "CO2e" Mean?

A compliant report will tell you the weight (in tonnes) of all of the greenhouse gases you emitted – carbon of course, but also methane, nitrous oxide and others.

This is expressed as a single unit in your footprint – something called “CO2e” or “carbon dioxide equivalent”.

In a nutshell, this is a way of putting all those different greenhouse gases (like methane, nitrous oxide, and good old carbon dioxide) onto a level playing field so you can compare them properly.

Each greenhouse gas has a different ability to trap heat in the atmosphere—methane, for example, is about 28 times more effective than CO2 at warming things up over 100 years. In other words, if you emit 1 tonne of methane, it has the same effect as emitting around 28 tonnes of CO2. This potency in comparison to carbon is called the Global Warming Potential (GWP) of the gas.

To calculate CO2e, you take the weight of each greenhouse gas you’ve emitted, multiply it by its global warming potential (GWP), and then add them all up. Voilà, you’ve got your carbon footprint expressed as CO2e.

Here’s a worked example. Suppose your business emits 100 tonnes of CO2 and 10 tonnes of methane. Then the calculation would look like this:

Carbon: 100 tonnes * 1 (GWP) = 100 tonnes of CO2e

Methane: 10 tonnes * 28 (GWP) = 280 tonnes CO2e

Total CO2e = 100 + 280 = 380 tonnes CO2e

This handy method lets you compare apples with oranges, or rather, methane with carbon, and gives you a clearer idea of your overall impact on global warming.

In reality, you usually don't need to worry about adjusting for GWP, because the "emission factors" used in the calculation (see below) already do this.

How Does a Business Calculate Their Footprint in Practice?

Calculating a carbon footprint is actually fairly simple, in theory. It involves collecting a range of data from across your business (things like the energy you used, the miles you travelled by plane), and combining that with something called an “emission factor” – basically, a multiplier that converts your data into an estimate of your emissions.

The challenge is finding the most accurate, comprehensive activity data, which might be difficult or time-consuming - especially for an SME.

Activity data

This is the raw material of your calculation - the amount of energy used, miles driven, materials consumed, etc. It’s the actual stuff that causes emissions.

Emission factors

These are the magic numbers that tell you how much CO2e is produced per unit of activity. They are almost always expressed in CO2e already (i.e. they account for the different effects of all greenhouse gases), so there’s usually no need to worry about the GWP calculations we ran through above.

Where Do Emission Factors Come From?

Now, where do these emission factors come from?

They’re calculated by the academics who study different processes and activities that produce greenhouse gases. These studies consider various factors like the type of fuel used, the efficiency of the technology, and the conditions under which the activity takes place.

For example, the emission factor that tells you how to convert your electricity usage (in kWh) into emissions is calculated by looking at the mix of energy sources (coal, natural gas, renewables) in the grid over a period of time (usually a year) and how efficiently the power plants operate.

These emission factors are then compiled into handy databases by organizations like DEFRA in the UK, the Intergovernmental Panel on Climate Change (IPCC) or the U.S. Environmental Protection Agency (EPA). Businesses can then use these standardised factors to ensure that their carbon footprint calculations are as accurate as possible.

Conclusion

So, there you have it—your carbon footprint is essentially a measure of the greenhouse gases your activities produce, and it’s something that businesses, in particular, need to keep an eye on. The GHG Protocol provides the rules of the game, ensuring everyone measures their emissions in the same way, and the concept of CO2e helps make sense of the different gases involved.

Understanding how to calculate your carbon footprint, from gathering activity data to applying emission factors, is crucial if you want to get a handle on your environmental impact. And as the world increasingly focuses on sustainability, managing your carbon footprint isn’t just a good idea—it’s becoming an essential part of doing business.

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