## 4 Discussion  
The results of this study show that the wear2 wearTM jacket does perform better among a wide range of environmental categories compared to a traditional linear produced jacket, because well implemented CE principles allow for the substitution of primary materials with secondary ones. This substitution is the very core idea of CE. CE in LCA terms means that product systems are connected with each other by reuse or recycle activities. This has been done in this study as explained in Section 2.2. As a result of CE practices, the wear2 wearTM product system requires fewer primary materials and incinerates fewer materials at the EoL. This reduces the impacts, especially in the categories photochemical smog formation, respiratory inorganics, human toxicity and water scarcity. Those results are reasonable. The pollutants emitted from the combustion of fossil fuels and waste in incineration plants, such as particulate matter or oxides of nitrogen, cause photochemical smog, respiratory symptoms and have in general effects on human health [30]. Thus, reducing the combustion of waste and the production of PES (which is based on fossil fuels) by means of CE principles leads to the reduction of impacts in the mentioned impact categories. The reduction of the water scarcity indicator is already sufficiently discussed in the result section and requires no further discussion here. Naturally, the direct reduction in primary PES material production (and thus of fossil fuels) reduces the impact of the circular jacket in the climate change category and subsequently the acidification of freshwater, as freshwater bodies absorb some of the anthropogenic CO2 emissions [31]. Overall, the results are consistent when interpreted in a wider scientific perspective. However, several limitations still exist which are identified here. While all the partner companies provided detailed data for their production processes, data from some of the subsuppliers were not available and proxies have been used instead. For example, a Chinese company producing the jacket's buttons, was not able to deliver data for their manufacturing process. Additionally, in some cases the energy inputs were calculated indirectly. For example, the natural gas input for the production of the fabric cannot be measured exactly in the production facility. Only the overall natural gas input of the fabric supplier over the course of the year was available. However, the energy inputs differ by the type of fabric. Therefore, the exact amount of natural gas required for the specific PES fabric is unknown. Instead, an average energy requirement per kg of fabric produced was calculated, using the amount of materials that the fabric supplier produces over one year. A further limitation involves the comparison of the wear2 wearTM with the linear jacket. As explained in the results section, the linear jacket is simply the copy of the wear2 wearTM version without the circular elements (namely the PET bottle input for the first loop, reuse of the zipper, and recycling at EoL). Producing a jacket is a complicated endeavor consisting of various components and production steps. Assuming that the linear jacket is equal to the wear2 wearTM jacket (except for the circular elements), it is sufficient for the goal of this study to analyze the environmental consequences of implementing CE elements into a textile product system. However, a comparison to a jacket that exists on today's market can lead to more findings about the environmental performance of the wear2 wearTM jacket--and CE textiles in general. For example, a comparison between a durable (but nonrecyclable) and a circular (but less durable) textile products that are produced with different technologies, is a very interesting question with possible findings being relevant even beyond the textile industry. Regarding the assumptions made in this study, two points need further thoughts.