A new line of trainers from On incorporates a renewables-based ethylene vinyl acetate (EVA) grade designed specifically for use in midsoles. By using the new material for the midsole, a 45% lower carbon footprint is achieved compared with one made from traditional fossil-based materials.
EVA is a lightweight, foam-like material that provides comfort, cushioning, and firmness, making it ideal for midsole applications according to Borealis. But what exactly is in this new EVA?
Borealis, the material manufacturer, claims: ‘feedstock is sourced entirely from waste and residue streams, including vegetable oil production residues, waste oils, and by-products from the timber and food industries.’
On, the product manufacturer, states: ‘the shoe’s midsole is made with bio-attributed Zero-Gravity foam, which uses renewable materials from ISCC+ certified bio feedstock, such as waste cooking oil.’
Borealis add: ‘The entire portfolio is ISCC PLUS (International Sustainability & Carbon Certification) certified, ensuring full traceability from point of origin through the entire supply chain.’ This statement does then suggest that the material is bio-attributed as suggested by On.
This is another example of how the terms mass balancing and/or bio-attributed are being used or not used, depending on who and how they are being used. The mass balancing process is complex to understand, so it is understandable that product manufacturers often omit the details.
However, in this case, it seems that the materials manufacturer is not being completely upfront about the content of their EVA. If the EVA is bio-attributed, it means that a small quantity of renewable organic feedstock (like vegetable oil) has been combined with a large quantity of fossil fuels. This means the end product is actually primarily made of fossil fuels, although it has been “bio-attributed” – as an audit process has allowed the product manufacturer to claim the full benefit of sponsoring the inclusion of vegetable oil by the material manufacturer. For the environmentally conscious consumer, this means that they are running on oil, while the marketing messaging may have led them to believe they are running on foams made from renewable organic material.
In this case, it is the product manufacturer that is being clearer in its messaging, but this is not always the case. We need clearer and more consistent messaging to prevent mass balancing from being labelled greenwash.
It must be highlighted that mass balance does deliver an environmental benefit – less fossil fuel was used to make the material. But consumers, who are often paying a premium to buy more sustainable products, need to be told the full truth about the ingredients in their purchases.