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Measuring your carbon footprint

Looking at the techniques used to calculate a carbon footprint and its applicability to the footwear and leather industries.

by John Hubbard

Image © Kilian

There is increasing pressure from consumers for more information about the sustainability of everyday products. One common measure of the environmental impact of a product is its carbon footprint.

A carbon footprint is a measure of the amount of greenhouse gases emitted during a particular process. The process can be as limited as the manufacture of a particular product or article, or it may be as complex as that generated by an entire global organisation. A carbon footprint is expressed as a tonne equivalent of carbon dioxide (tCO2e). There are six gases that form the collection of greenhouse gases (GHG) associated with global warming (see table 1). While carbon dioxide is the most abundant, the other gases are more potent with respect to their potential for global warming. In table 1, these are expressed in comparison to carbon dioxide, which is given a value of ‘1’. Not all emissions are man-made or from industrial processes. For instance, a considerable amount of methane is released during the grazing and rearing of cattle.

Table 1: The global warming potential of greenhouse gases
Chemical Global warming potential
Carbon dioxide (CO2) 1 (least potent)
Methane (CH4) 21
Nitrous Oxide (N2O) 310
HFCs 140-11,700
PFCs 6,500-9,200
Sulphur hexafluoride (SF6) 23,900 (most potent)

Why do we want to measure a carbon footprint?

The way in which the carbon footprint is measured for an organisation or product will depend on many factors, and it is important before you start to have a clear idea of what the data will be used for. For some organisations, it can be an internal measure of environmental efficiency which can be used to show year-on-year improvement. Other measures may be required to show the footprint as part of an agreement with the organisation’s customers, and for some it may be a way to demonstrate a commitment to environmental accountability and will be made available for the public to view.

The way the results will be expressed is also important. One approach is to measure a corporate footprint which takes into account all different sectors of the business and expresses it as one complete figure. This approach may be appropriate for a diverse organisation with a range of different productions. The second method is where the total carbon footprint is divided by the production to give a carbon footprint total per unit of production. This allows final users to understand the impact of the items that they purchase and is most suited to a situation where large numbers of identical or very similar products are manufactured together.

Once the carbon footprint is measured, it may be desirable to demonstrate that the company has offset this carbon or a portion of it. This is normally achieved by making a payment to an offsetting organisation that will run a range of schemes to improve energy efficiency in developing countries. If this approach is desirable, it is important that the offsetting partner organisation is accredited and the activities it undertakes can achieve verifiable carbon reduction. There are mixed opinions as to the benefits of carbon offsetting – some campaigning groups do not recommend it as they feel that as long as organisations can offset their behaviour, it will make it more difficult to move to a low carbon economy in the long term.

What do I measure?

Models have been developed to give guidance to organisations in calculating their carbon footprint, and research will be required to identify the most appropriate approach for each calculation. As long as the method and basis used for the calculation is set out alongside the results, any of the models can be used. However, where comparisons need to be made between results, they must be calculated on the same basis for the comparison to have credibility.

Emissions can be split into three types – referred to as ‘scopes’ – which are defined within the Greenhouse Gas Protocol published by the World Resources Institute (WRI) and the World Business Council for Sustainable Development:

For a basic carbon footprint, scopes 1 and 2 emissions will be totalled together. To achieve a more advanced calculation, scope 3 emissions will also be included, but here it will be more difficult to gather accurate data. For instance, how do you accurately calculate the emissions associated with your employees’ business travel?

How can I verify the result?

There is an international standard giving guidance on performing carbon footprint calculations (ISO 14064), and it is possible to have your calculations verified by a third-party auditor to lend credibility to any claims that you make about your carbon footprint. The verification will take account of the methodology, data collection techniques and the calculation process that was used.

Once you have the result of this calculation, it is often a good time to set targets for reductions, either as a corporate entity or on a product-by-product basis. These targets can be achieved through a variety of means, including switching to energy generated from a renewable source, improved energy efficiency of processes, and a reduction in the weight of packaging used. As energy use is one of the biggest contributors to the total carbon footprint, a reduction in energy consumption should in turn lead to a real measurable monetary saving, especially for a large energy user.

Targets for carbon reductions can be achieved through a variety of means, including switching to energy generated from a renewable source

How can we help?

Please email if you have questions about measuring your carbon footprint, or other sustainability issues.

Publishing Data

This article was originally published on page 24 of the October 2019 issue of SATRA Bulletin.

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