How to measure a carbon footprint?
In this article I discuss 5 simple steps to help you on how to measure a carbon footprint. Following these steps will ensure that you get a consistent and reliable measure of your environmental impact. So without further adieu. (image attribution: digitalart)
Step 1. Define the boundary for your carbon footprint
Boundary is an important concept in carbon footprinting as it sets the constraints for consistent year-on-year assessment. Failing to define the carbon footprint boundary can inhibit comparisons against benchmarks / other organisations and could also undermine meaningful monitoring of performance.
The boundary of an organisation’s carbon footprint can be drawn across three levels.
- Operational control: this approach draws a boundary around the elements that a company has operational control over. Using this approach means that everything that a company operates gets captured in the carbon footprint. This can extend into the supply chain if an organisation has sufficient operational control over suppliers.
- Financial control: this approach covers all elements that a business financially controls. Often this excludes elements which a company may operate but not financially control and therefore using this approach can result in a smaller carbon footprint.
- Equity: this approach includes all elements that a company owns. If a company has part ownership then the proportion ownership is used to calculate the relevant carbon footprint attributable to that company. Of course there can be circumstances where a company operates and financially controls an asset but does not own the asset. In such a scenario these elements are excluded from the carbon footprint when using the equity approach
Recommendation: unless your business has a very complex business structure then we recommend that you use an operational control approach
Step 2. Decide which emissions will be included under scope
Scope refers to the emission types captured in a carbon footprint. The scope of an organisation’s carbon footprint also breaks down into three components.
Scope 1 emissions cover all direct emission sources. These are emissions from assets that are either owned by a company ( i.e. fleet vehicle emissions from the consumption of fuel) or emissions produced through an on-site activity (i.e. emissions from the burning of natural gas in a company’s boiler)
Scope 2 covers all indirect emissions or more specifically emissions derived from the production of purchased electricity. Here a company hasn’t actually produced the emissions associated with electricity generation but due to the consumption of electricity to power lights, equipment etc. we can say that the company are indirectly responsible for these emissions.
Finally scope 3 covers all other indirect emissions which are not as a result of the consumption of purchased electricity. This includes a wide array of emission sources including waste, consumables, staff commute, supply chain emissions,water use etc.
Recommendation: at a minimum an organisation should capture scope 1 and scope 2 emissions.
3. Define your carbon footprint period
A carbon footprint is typically measured across an annual period. When choosing your period for measurement it is best to think of other reporting cycles which can be used as the set timeframe. Many companies like to measure their carbon footprint against their financial reporting year. Other companies measure their carbon footprint against the calendar year. Either way, choose an annual period which takes advantage of existing reporting structures.
4. Use a practical approach to collect annual data
Once you have defined your boundary and the type of emissions you are going to capture, you’ll then need to collect data on usage. Data is often stored in odd places and formats so it is important that a systematic approach is followed. Here are some top tips you can use.
- Data should be for an annual period. If you can’t get complete annual data you will have to use what you know about a sample of data to annualise your information. For example, if you know that you used 1000 litres of petrol for your fleet vehicles for the first six months of your carbon footprint period then you could extrapolate that you will use 2000 litres over the year. Note: be careful of seasonal or business fluctuations. Your vehicles may drive a lot more during the Christmas busy season which would distort the results if you don’t correct for this.
- The format of the data can also come in many shapes and forms. Sticking with fleet vehicles as an example, you may not know how much fuel you have consumed. Indeed you may not know how many miles your vehicles have driven. You may only know how much you spent. If you don’t have primary data (i.e. litres consumed, kWh used etc) you will have to convert your secondary data (miles driven, electricity spend etc.) into a primary data. This can be done by using proxies – miles per gallon, cost per kWh etc.
- The last port of call if you cannot get real data is to use estimation. Here the best approach is to look at benchmarks (e.g. kWh per square foot for a particular office type) or basic knowledge of your operations (e.g. average trip is x km and we do 10 deliveries a day, therefore…). Note, estimation should be used as a last resort and always stated in any published result.
5. Calculate footprint
After you have collected all your relevant annual data the task is then relatively simple. You need to use a carbon footprint calculator or carbon conversion factors to calculate your organisational carbon footprint. There are many carbon footprint calculators on the internet that can be used for free. I would however, check that the calculator you choose follows internationally recognised methods for carbon footprinting and uses emission factors which are relevant for your organisations country. The sustainable business toolkit provides an internationally compliant carbon footprint tool which can help you quickly choose the correct emission factors and input your data for a detailed carbon footprint assessment.
Best of luck calculating and improving your carbon footprint.
About the author
Mark Whitman is a sustainability and management consultant with significant experience in carbon management, corporate social responsibility and environmental management. He has worked with major companies such as Microsoft, BP, Westpac and Aegis Group. Mark holds a first class bachelors degree in economics and environmental science from the University of Cape Town and a masters degree from Cambridge University. He founded the Sustainable Business Toolkit in 2011 and is the lead editor for the website.