Just before the European Outdoor Summit at Tegernsee last month, W.L. Gore & Associates announced for the first time the findings of its Life Cycle Assessment (LCA) for outdoor shoes. The study takes into account numerous factors including the environmental impact of water usage and transportation.

The results of the test, which were conducted on a pair of hiking shoes laminated with Gore-Tex for 3.5 years, show that it emitted a total of 27.1 kg of CO2-equivalent, comparable to the environmental impact of driving 100 kilometers in a mid-sized car that consumes 7.5 liters of fuel per 100 kilometers.

If the product lasts longer, the impact is proportionally lower. For this reason, the choice of longer-lasting materials is crucial, Gore's experts say. The manufacturing of the materials, including the membranes, represents about half of the impact. Textiles and the polymers in the sole have a higher impact than leather, which can be as low as 3.8 percent of the global warming potential (GWP) depending on where the leather comes from.

Looking at it from another point of view, the production of the raw materials and the distribution of the product account for more than two-thirds of its GWP. Gore is focusing on energy savings during the manufacture of its membranes, which contribute 3 kilos of CO2 emissions or 11.9 percent of the GWP. No comparable figures are apparently available for the membranes of other suppliers.

Officials at Gore claim that the recyclability of the membranes and other components of the shoes is not a significant factor of sustainability, especially because the soles and other components cannot be easily recycled. In any case, its study indicates that the “end of life” disposal of the shoe would add only 2 percentage points to the global warming potential.

Comparatively, Gore says, buying two less durable pairs of waterproof/breathable hiking boots over the same time period would result in carbon emissions of 52.4 kg CO2-eq. in order to keep feet dry and comfortable, due to the risk of early failure and the need to use another pair. This would imply an environmental impact equivalent to that of driving 190 km instead of 100 km.

Gore points out that it has been involved in sustainability efforts since the 1980s, starting with the use of adhesives in apparel. Already in 2013, Gore published the results of a LCA study for a Gore-Tex jacket covering the entire value chain “from cradle to grave.” A five-year test of the jacket indicated 72 kilos of CO2 emissions, with 35 percent of that coming from washing and drying.

The LCA studies on apparel and footwear were carried out with input from third-party experts such as the Öko-Institut Freiburg e.V. and the U.S. Institute for Environmental Research in Vashon Island, Washington state.

Incidentally, a speaker at the European Outdoor Summit indicated that mankind is getting a lot of toxic substances in children's metal toys, wallpaper, toilet paper, PET bottles, chewing gums, beer cans, etc. He suggested using the notion of “eco-effectiveness,” instead of “guilt management.”

He pointed to the Incycle program of Puma, with 128 products that are recyclable cradle-to-cradle, including shoes.