Carbon and water footprints assessment of cotton jeans using the method based on modularity: A full life cycle perspective

Cotton jeans with huge market demand have a great potential negative impact on the ecological environment, especially in terms of climate change and water depletion. Given the complexity and difficulty of carbon and water footprints assessment in the textile sector due to the plethora of material varieties and life cycle processes involved, previous researchers have embraced process modularity (i.e., decompose life cycle processes into components) as an auxiliary technique. Although modularity enhances overall flexibility and assessment efficiency, a holistic view is missing for the comprehensive consideration of both product production and consumption processes. Moreover, extant studies only take a limited or even a single manufacturing process as a case demonstration, rather than examining the applicability of the modular method throughout the product life cycle. It is therefore unclear how the interaction and assembly of different process modules will unfold when multiple stages are involved. Accordingly, this study extended the research boundary to the whole life cycle of textile products, and verified the feasibility and practicality of the method with a computational case study of a pair of cotton jeans. The results showed that the total impacts of carbon footprint, water scarcity footprint, water eutrophication footprint and water ecotoxicity footprint were 90.37 kg CO₂ eq, 13.74 m³ H₂O eq, 1.67 × 10⁻² kg PO₄³⁻ eq and 112.41 m³ H₂O eq respectively; and finishing, cotton cultivation and laundering processes were major contributors to these environmental impacts. The study also demonstrated how different cotton jeans parameter values from the life cycle affect the carbon and water footprints through sensitivity analysis. Furthermore, based on the decomposed modules, 12 common use patterns in China were discussed, which confirmed the superiority of the modular method without recalculation from scratch. The scenario analysis revealed that a combination of top loader machine washing and line drying once a month without ironing for cotton jeans within a two-year lifespan was the most promising alternative. The results obtained in this study can provide methodological and technical guidance for follow-up research and application. In the future, other product categories and impact indicators can be integrated into the modular method.