The HNST footprint: Life Cycle Assessment of 1 pair of jeans
Denim is immensely popular. Conventional jeans are usually made out of cotton and are known for its high environmental impact. It is estimated that one pair of jeans requires approximately 3 kg of raw cotton and 7000 liters of water. On top of that, denim dyeing and finishing is related to the emission of hazardous chemicals (such as cadmium, mercury and lead) into freshwater bodies resulting in harmful effects for local ecosystems and communities.
Denim is considered to be ‘green’ when the raw material is blended with recycled or sustainable fibers and when the production process uses less water and chemicals. At HNST it is our mission to produce jeans that have nothing to hide with the lowest impact possible. Therefore, we conducted a Life Cycle Assessment (LCA) to calculate the environmental impact of our jeans.
LCA is a broadly accepted method to scientifically calculate and interpret the environmental impact of a product throughout its entire life cycle. For our LCA calculation we used the MODINT Eco-Tool.
Every LCA starts with a careful material analysis. This is necessary to allocate the different environmental impacts (e.g. water consumption, global warming, eutrophication, acidification, etc.) to the different materials in the product. This is how we determined the functional unit of our LCA: being one pair of jeans, consisting of 600 grams denim (97,6%) and 5 grams pocket lining (2,4%).
Next in the LCA, we take the different life stages of HNST jeans under the loop;
- Raw material extraction: mechanical recycling, Tencel® and Greek cotton
- Production process: spinning, weaving, dyeing, sewing and washing with respect for people & planet
- Transportation: our jeans is entirely produced in the EU
- Use phase: domestic washing, drying & ironing
- End-of-life: mechanical recycling
Here you can find a detailed overview of our circular supply chain.
The LCA methodology results in scientific calculations, quantifying environmental impact in various impact categories. Here we will discuss 4 of the most relevant impact area’s, being:
- Water consumption (L): freshwater taken from the environment or water that has been contaminated by e.g. releasing chemicals into rivers
- Land use (m2): land occupied by for example the growth of virgin fibers
- Primary energy content (MJ): the amount of energy consumed during the entire product life cycle
- Carbon emissions (kg CO2 eq.): the release of greenhouse gases causing global warming is expressed in carbon dioxide equivalents (CO2 eq.)
According to industry standards, one conventional jeans uses about 7000 liters of water. In comparison, one HNST jeans only uses 361 liters of water, which means we are reducing water consumption with 95%.
The HNST LCA takes into account water consumption of “green water”, “blue water”, “dilution water” and “virtual water”, presenting a complete picture. If you want to know more about this, feel free to reach out.
When taking a closer look at the water consumption breakdown of an HNST jeans (see graph below), one can remark that more than 85% of water consumption can be allocated to the 23% of virgin cotton used in the HNST denim fabric. As can be seen from the graph below, water consumption of the mechanically recycled cotton and Tencel® is almost negligible. Mechanical recycling is a low-impact technique which does not use any water, chemicals nor heat and only needs little energy in comparison to chemical recycling or virgin fiber production.
1,3 square meter is needed to produce one pair of HNST jeans. When taking a closer look at the land use related to the production of an HNST jeans, the majority of land use (92%) can be contributed to the cultivation of virgin cotton (while cotton only represents 23% of the fabric composition). By using recycled fibers we are reducing our land use significantly. Next to growing cotton, growing trees for our paper and cardboard packaging is responsible for 8% of our land use.
Primary energy content
The graph below gives you an insight into the breakdown of the primary energy consumption of one HNST jeans, which totals to 103,8 MJ. The majority of the primary energy is used in the construction phase of the jeans due to the electricity needed for spinning and weaving off the fabric.
Construction is followed by fiber materials referring to the energy used for mechanical denim recycling. In addition, coloring appears to be a large contributor due to the thermal energy and electricity requirements of the Smart-Indigo process. Both the process of mechanical recycling and Smart-Indigo are relatively high contributors in the low-impact HNST process but are of small absolute value when compared to industry standards.
The production of one HNST jeans emits 5,6 kg of carbon dioxide, 76% less than the average carbon footprint of a jeans being around 23,3 kg of carbon dioxide. To put things in perspective, the HNST carbon footprint of 5,6 kg of CO2 is equivalent to driving an average gasoline car for about 47 km or eating 180 grams of beef.
Limiting CO2 emissions is one thing, in order to tackle climate change and become CO2 neutral, complimentary offsetting is needed. At HNST we go even further. Inspired by the Cradle to Cradle® philosophy, we aim to be carbon positive. This means we are working together with WeForest to compensate (three times) our carbon footprint by planting trees that use photosynthesis to extract and store CO2 from the air, positively impacting climate change.