Clean Tech 101

What is a Carbon Footprint?

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Dec 8 2007

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The term carbon footprint commonly refers to the total amount of carbon dioxide (CO₂) emissions and other greenhouse gases (GHG) that an organization or individual is accountable for producing. The carbon footprint for products or events can also be calculated.

Calculating Carbon Footprint

Emission sources including direct and indirect use of fuels such as travel made by employees, product transportation or other emission sources by the organization throughout the supply chain are used to determine the total carbon footprint of an organization.

It is important to remember to include a wide range of sources of emission when calculating the total carbon footprint of an organization to provide a full insight of the organization’s environmental impact.

In an attempt to calculate a reliable carbon footprint, it is necessary to adhere to an organized procedure and thoroughly categorize origins of all possible emissions. A common classification method is to sort and record the emission level in which an organization has control over.

There are a number of carbon calculation standards, but many organizations will use the GHG Protocol. The GHG Protocol is the most widely used international tool for calculating and managing GHG emissions. It is the product of a collaboration between the World Resources Institute and the World Business Council for Sustainable Development.

It provides standard requirements and guidance for corporate-level company emissions calculations, product life cycle standards and GHG protocol for cities.

Classification of Greenhouse Gas Emissions

On the basis of recording emissions that an organization has control over, greenhouse gas emissions can be classified into three main categories:

Direct emission resulting from the participation of organization activities
Emission caused by the use of electricity
Indirect emissions from services and products.

Direct Greenhouse Gas Emission Resulting from the Participation of Organization Activities

Direct emission is the result of fuel combustion and results in carbon dioxide (CO₂) emission. An example of this is the combustion of gas or other fuel sources in the workplace to generate heat for a heating system.

Another example involves chemical manufacturers that produce methane gas. Such manufacturers can be grouped as organizations directly emitting other greenhouse gases. Another activity that falls into this category is the use of fertilizers that produce nitrous oxide emissions.

Greenhouse Gas Emission Caused by the Use of Electricity

Lighting and equipment used in households and workplaces normally requires the use of electricity. Nuclear, fossil fuels (such as coal) and renewable resources (such as wind and solar energy) are used for the generation of electricity. In 2017, the UK obtained 18% of its primary energy from low carbon sources, according to the 2018 National Statistics publication, UK Energy in Brief. Biofuels, which include anaerobic digestion, wood pellets, and energy generated from waste made up 35% of the total low carbon energy sources. The UK’s coal use in electricity accounted for 62% of the total demand, but the total consumption in 2017 was just 14.2 million tonnes, down from 51.4 million tonnes in 2010. By using or purchasing electricity, organizations and households are indirectly responsible for CO₂ emission.

Indirect Greenhouse Gas Emissions from Services and Products

Organizations are also responsible for emissions resulting from services or products purchased. The carbon footprint of an organization is influenced by the way in which organizations use services and products.

An organization or company that produces or manufacturers a product is indirectly responsible for the emission of CO₂ during the preparation and transportation of raw materials. The disposal of the product can also be indirectly contributing to carbon emission to the organization or company.

Comparison and Understanding Published Carbon Footprints

It can be concluded that generating a full carbon footprint covering all three types of emission stated above can be a complex and difficult task.

Understanding published carbon footprints can further add to this complexity.

Published carbon footprints are rarely used for comparison for a number of reasons:

Not all organizations or companies use the same approach for the calculation of their carbon footprint. They may also use different categorizations for their carbon emissions regardless of emerging international standards.
Various units are used for the expression of carbon footprints amongst different organizations. For example, one organization may express their carbon footprint on a time period basis, whereas another organization may express their carbon footprint as per product purchased, or on a per event basis.
Some organizations may include all greenhouse gases in their carbon footprint, expressing their carbon footprint in tonnes of CO₂ equivalent. On the other hand, organizations can disregard other greenhouse gases and only state the emission of CO₂.

Final Note Regarding Carbon Footprint

The most suitable method for determining a carbon footprint is often dictated by its intended use. In some instances, it may be feasible to perform a basic carbon footprint determination; however, in some cases a more in-depth procedure may be required.