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Environmental impact during a product’s life – part 2

In this article, we focus on material selection and sourcing.

by Nicola Pichel-Juan

This is the second in a series of articles considering the environmental impacts throughout the footwear lifecycle and the ways in which those effects can be reduced. The single biggest impact that will be identified in any carbon footprint analysis or lifecycle assessment for footwear is likely to come from the materials and components that make up the item. This aspect will typically far outweigh the impact from the manufacturing process itself, or from shipping the finished goods.

The obvious starting point might be to ask the questions “what makes a material sustainable?” or “which materials are sustainable?” However, identifying and defining materials as ‘sustainable’ is not that straightforward, and there are many other questions to consider. Is a material sustainable because it is made from recycled content or because it can be recycled? Is a biodegradable material sustainable? What about compostable materials? Does a sustainable material need to be vegan? Is it more important to ensure that a material is not made using any fossil fuels? Can a material only be sustainable if it is carbon neutral? Does a sustainable material have to be certified or accredited to one of the many voluntary standards that are available? This hopefully demonstrates that there is no ‘one size fits all’ definition of a sustainable material.

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The single biggest impact in any carbon footprint analysis or lifecycle assessment for footwear is likely to come from the materials and components used

Most materials are highly unlikely to meet all the criteria suggested above, and there can often be trade-offs that must be made. As an example, cotton is a natural material, which could be seen as preferable to producing new materials from fossil fuels. However, large amounts of water are typically consumed to grow cotton, which can be particularly problematic in parts of the world with water scarcity challenges – although there are a number of schemes that work with farmers to reduce water consumption and allow cotton to be traced back to an individual farm.

Material breaking down in one of SATRA’s compostability tests

While both rubber and leather have been linked to deforestation (in specific regions of the world), they are durable, natural materials that do not lead to additional fossil fuels being extracted and consumed. Of course, it can also be argued that leather is a by-product of the meat industry and the skin would exist anyway, regardless of whether or not it is tanned into leather. A disposal problem can arise if the skin is not utilised in order to make leather.

Selecting recycled materials or materials with at least some recycled content (such as extrudable polyethylene terephthalate – ‘ePET’) may seem to be an ideal solution. Nevertheless, in some instances the recycling process can consume large amounts of energy and the resulting material may be of a lower quality and unable to be recycled again.

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Rubber is a durable, natural material that does not lead to additional fossil fuels being extracted and consumed

Material pros and cons

Considering the complexity and conflicts described above, how can any organisation be confident in making any decisions about selecting and sourcing sustainable materials? SATRA firstly recommends that the desired sustainability credentials are clearly established for any given material. This will vary from company to company and even from product to product. It is then important that each individual material and its supply chain is considered in its own right.

For example, a leather produced in a tannery working to high environmental stewardship standards (such as Sustainable Leather Foundation/Leather Working Group), that has improved its energy and water efficiency, reduced effluent discharges, and has full traceability of its hides back to the slaughterhouse, will have a much lower environmental impact than leather from a tannery with a supply chain that does not achieve the same standards and cannot trace the origin of the hides it is using.

The location where a material is produced will also have a considerable influence on its environmental impact. The first impact to understand comes from how far a material needs to be shipped to the first-tier production site. Obviously, the further something is shipped, the greater the impact will be. Sea and road freight both have relatively low impacts. However, if a material must be routinely transported halfway around the world by air to meet production requirements, the high impact of the air freight will likely negate any other work that has been done to make the material more sustainable. Shipping by air has a CO2e impact (the ‘e’ stands for ‘equivalent’) that is more than 50 times higher than transportation by sea.

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Shipping by air has a CO2e impact more than 50 times higher than transportation by sea

The second main impact comes from the factory itself and how the electricity it uses is generated. If a production site utilises standard electricity predominantly generated through the burning of fossil fuels, its impact will be much higher than a supplier in an area where electricity is generated wholly or partially through renewable sources, or a supplier generating at least some its own renewable energy on site – for instance, from a solar panel installation. If it is feasible for a facility to transition to generating its own renewable energy, it will greatly reduce the environmental impact of anything that it produces and in the medium- to long-term this should also offer cost savings over the purchase of local grid energy. With the huge increases in energy prices being seen in some parts of the world at the moment, the payback periods for the installation costs of technology such as solar panels are becoming ever shorter.

All this demonstrates that while it might be useful to have a general understanding of the typical sustainability credentials and impacts of a particular material type, it is very important to understand a material’s supply chain in detail. A seemingly identical material made in two different factories could have very different impact levels. A further consideration is the impact of a material on the environment at the end of its life, which will be discussed in more detail in a future article in this series.

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A major environmental impact comes from how the electricity used in a factory is generated

What about new sustainable materials?

New materials and components are constantly being launched on the market that are promoted as being sustainable. Many of these materials are bio-based – produced using substances derived from living organisms – and can contain anything from algae to pineapple or corn starch to dandelion rubber. In terms of understanding if these materials are sustainable, the same challenges apply as previously discussed.

Each material needs to be considered in its own right, taking into account its supply chain. While many bio-based materials will have good sustainable credentials, other bio-based materials – while repurposing an existing waste stream (often from the food industry) – may have been blended with plastics or have a plastic backer applied to them. That plastic must then also be considered in order to understand the material’s overall impact.

A question frequently asked of SATRA is “What are the performance requirements for a sustainable material?” The answer to this question is very simple – any new materials coming onto the market need to meet the same standards as more traditional materials used for the same application. SATRA has previously published articles – such as ‘Biofabricated and alternative materials’, which offered some insight into future alternatives to ‘traditional’ footwear materials – and we continue to test new types of material being sold to the footwear industry. In addition, a recording of the recent SATRA webinar entitled ‘Innovative materials as an alternative to leather?’ can be viewed at

How can we help?

Please contact for further information on the various environmental impacts of materials and how to calculate them.

Publishing Data

This article was originally published on page 10 of the November 2022 issue of SATRA Bulletin.

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