Design & Production of Sustainable Shoes
Design & Production of Sustainable Shoes
Designing and producing sustainable shoes can be difficult but is an important factor to consider in today’s world of increasing climate change and climate change activism. We must think ahead and start with the design and material selection, to reduce our carbon footprint as consumers and manufacturers in the shoemaking industry. The modern mass-produced shoe, made of textiles, leather, plastic, and rubber parts all glued and sewn together is not environmentally sustainable.
The global footprint of shoemaking
The modern shoe is very difficult to recycle. The shoe factory workers secure the upper parts with stitching, and firmly bond the outsole parts with PU cement. Used shoes and sneakers are almost impossible to break down into useful components for recycling. The manufacturing of these components themselves consumes vast amounts of water and energy while creating mountains of post-industrial and post-consumer waste.
Your choices for sustainable shoe production
With that qualification said, footwear designers, shoe developers, product managers, and factories can make choices to help reduce the negative environmental and social impacts of shoe production. There are no magic shoe materials or production techniques that can make a shoe entirely green, sustainable, or ethical. Depending on your own environmental and social priorities, there are many options available.
We will consider different aspects of shoe production that can make your shoes more or less environmentally sustainable:
1. Sustainable shoe material selection
2. Environmentally friendly footwear production processes
3. Waste reduction in footwear manufacturing
4. Sustainable shoe material selection
Organic vs. man-made textiles
If your priority is drinking water preservation, then using man-made textiles is a better choice than cotton and other natural textiles. Both cotton and man-made fibers require large quantities of water for dyeing processes. Fortunately, the water in an industrial facility can be recovered, recycled, and reused in a closed-loop system. In Southern China, local governments have forced textile dyeing houses to relocate into industrial estates with controlled water purification facilities.
The process of growing cotton, especially organic cotton, consumes enormous quantities of water that is not reused in a closed-loop. Some studies estimate that more than 700 gallons (2,700 liters) of water is required to make the cotton for one cotton t-shirt! Yes, once we use water in the cotton fields, it does return to nature, but it is no longer available to drink or grow food crops.
On the flip side of cotton and natural fibers, is the production of man-made polymer-based fabrics such and nylon or polyester. The amount of water required to make these fibers is radically less, but the energy requirement is higher, and there is a greater danger of water contamination from petrochemicals.
Natural vs. man-made “leather”
Natural leather from animal hides also requires large amounts of water. According to studies done by a major leather producer, raising animals and processing their hides requires over 264 gallons (1,000 liters) of water to produce two square feet of leather. Two square feet of leather is enough to make just one pair of shoes. Raising animals and then processing leather into hides has a two-fold effect on the environment. The contaminated and harmful agricultural run-off plus water containing hazardous tanning byproducts. Water aside, the treatment of animals is a significant concern for vegan customers while the production of human-made imitation leather is not regularly considered a moral hazard.
As with fabrics, the human-made alternatives to natural leather have their environmental costs. Human-made synthetic materials are very often layers of polyester fabric, foams, and fibers that are fused together. These layers are nearly impossible to separate once the shoe has reached the end of its lifespan. Producing synthetic materials also consumes energy, and the danger of water contamination from petrochemicals is high.
Natural vs. synthetic rubber
Again, the choice of rubber compounds comes down to a choice of your environmental priorities. Natural rubber production leads to increased deforestation in Southeast Asia and reduces the amount of land available for food cultivation. Synthetic rubber production requires a combination of Styrene and Butadiene. Both are petrochemicals refined from crude oil. The production of these compounds requires significant energy inputs, and both are byproducts of oil production.
Although there are many material options, each comes with either an environmental or a social cost. When you make sustainable shoes, you need to decide where your priorities lie.
Shoe materials with recycled content
Another way to reduce the overall environmental impact of footwear production is to specify some of the many footwear materials made with recycled content. When reviewing materials for sustainable shoes, it is important to understand the difference between post-consumer and post-industrial waste. Many industrial processes create waste or scrap inside the factories. However, the supply factory will recover and reprocess these materials into the finished materials. For instance, the injection molding supplier will regrind, and re-mold wasted materials. Fabric factories will chop and re-purpose textile fibers. For many factories, this is a simple and smart way to save money. Factories will collect other post-industrial waste and send it out for reprocessing into various other products.
Post-consumer recycled content is produced when the raw materials are recovered from the waste stream after use. These products may cost more, as the materials may require complicated sorting, cleaning, and reprocessing. The amount of post-consumer content in a product depends on the physical properties required. Usually, higher physical test standards will demand lower post-consumer content. Fabrics are now available with 10% to 70% recycled content.
Textile factories now make many woven and knit fabrics made with post-consumer recycled PET plastic fibers. Shoe lasting-board suppliers now produce Strobel materials with both post-industrial and post-consumer waste. Paper fiber-based lasting boards often contain over 50% post-consumer waste.
Additionally, foam factories can now supply shoe footbeds and linings made with post-consumer and post-industrial recycled foam materials and new biodegradable additives are available that allow plastic to degrade in decades rather than centuries.
If you want to learn more about sustainable shoes, material selection, sustainable footwear design, and sustainable production, check out Chapter 26 of the Shoe Material Design Guide.