Image credit: Karen, used under Creative Commons license.
Dear Pablo: Say an average fancy t-shirt holds carbon footprint of 6kg but is never sold and sits in the warehouse of a textile/clothing production company. I take that same t-shirt and use it to make a new one. Does the new product inherit the same carbon footprint or is it less because I am repurposing it?
Questions such as this are an important part of Life Cycle Assessment (LCA). LCA has several standards associated with it, including ISO 14040:2006 (Life Cycle Assessment: Principles and Framework), ISO 14044:2006 (Life Cycle Assessment: Requirements and Guidelines), PAS 2050, and the new GHG Protocol Product Standard, but none of them are prescriptive enough to provide a clear answer. For example, the LCA practitioner has a lot of flexibility around defining boundaries and other variables so that two LCA studies of the same apple could yield different results. The value of LCA is that a clearly documented quantification process should produce repeatable and consistent results so that two apples could be compared. When the answer is not clearly given in the standards, we must rely on the guiding principles behind them; Relevance, Completeness, Consistency, Transparency and Accuracy.Life Cycle Assessment involves identifying the stages of the life cycle, sometimes defined as:
- Material Acquisition & Pre-Processing,
- Distribution & Storage,
- Use, and
In the case of the t-shirts the Use stage never occurs as the product is held in the Distribution & Storage phase. When the t-shirts are repurposed they go directly to their End-Of-Life phase while also entering the Material Acquisition phase of the new product. The repurposing of the t-shirts is essentially identical to a recycling process in which the input and output material have the same inherent properties. When recycling is involved the LCA practitioner has to chose between allocating the impacts and benefits of recycling to the previous product or the new product.
Another answer to this question could come be a matter of additionality, in other words, "what would have happened to the t-shirts had they not been repurposed?" Depending on the answer to this question, the embodied emissions of the new product could include all, some, or none of the emissions from the growing of the cotton, the production of the textiles, the manufacture of the t-shirts, and all of the associated transportation.
What If The T-Shirts Were Headed To The Dump?If the t-shirts were destined for the dump to make room in the warehouse, essentially written off at a financial loss, then the answer is easy. In this case the embodied emissions, all of the emissions associated with making the t-shirts, from the field and factory to the warehouse, remain the responsibility of the company that last bought them. The environmental impact of procuring the reclaimed t-shirts would be essentially free.
What If The T-Shirts Were Sold (Or Ownership Was Otherwise Transferred)?If the unused t-shirts were sold to the repurposing organization or individual, then the environmental impact would be passed along. This situation would be no different than a wholesaler selling t-shirts in the standard t-shirt supply chain.
Of course none of this applies if the t-shirts are repurposed within the same company. In that case, raw materials (t-shirts) are just being turned into finished goods, and the embodied energy of the t-shirt life cycle remains unchanged.
All of this misses the point though that, according to the reader's question, a new t-shirt has a carbon footprint (I prefer greenhouse gas life cycle impact) of 6 kg. From a consumer's perspective all t-shirts should be assumed to have an environmental impact in this range, unless they are bought from a thrift store or borrowed from a friend. This is, after all, the best way to know for sure that your t-shirt has the lowest impact possible.
Pablo Päster is a weekly columnist for TreeHugger.com and Principal Environmental Consultant at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
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