Reckoning: A Simplified LCA Methodology for Fashion Designers through a Case Study of Knitted Garments

Abstract

This thesis endeavours to propel sustainable fashion design practices in New Zealand by developing a simplified approach to the life cycle assessment (LCA) methodology. It aims to equip fashion designers with knowledge and tools to understand and mitigate the environmental consequences of their creation. Specifically, this study pursues the following three objectives: 1. to explore and quantify the environmental impact of garments for their Global Warming Potential (GWP), 2. to simplify the LCA method for everyday fashion design operations, and 3. to share experiences and insights of navigating the scientific realm of LCA methodology, with the fashion design community.

Grounded in pragmatic epistemology, this study adopts an exploratory approach. First, a comprehensive LCA was employed to evaluate the cradle-to-grave environmental impact of knitted jumpers in eight different life cycle scenarios. Two varied textile materials – wool and polyester, three different knitwear manufacturing techniques – cut-and-sew, fully fashioned, and integral knitting, and four distinct supply chain pathways were analysed for their GWP. Through the collection of primary and secondary data for fibre production, wet-processing and dyeing, garment construction, transportation and packaging, and the subsequent use and end-of-life phases, a comprehensive analysis was conducted.

The findings highlight disparities between wool and polyester jumpers in terms of their GWP. Woollen jumpers exhibited a higher GWP owing to factors such as fibre production, wet-processing, and subsequent spinning. However, it is important to acknowledge the limitations of the calculations, as some of the data used were unreliable for a precise comparative assessment. The study identified a need for New Zealand-specific data on merino wool production. Furthermore, it examined the Ecoinvent v. 3 database for ethylene —a fundamental raw material for PET and polyester fibre production—and discovered inaccuracies in the reported CO2 emissions. The research emphasises an urgent need to correct persistent errors in the Ecoinvent dataset for ethylene to facilitate reliable comparisons with natural materials. Processes such as the cut-and-sew method of knit garment manufacturing and transportation routes with minimal distances, in conjunction with local manufacturing, were found to be critical factors that substantially reduced emissions. The results revealed distinct use patterns and end-of-life practices for wool and polyester jumpers in New Zealand, underpinning their divergent environmental profiles.

Second, this study proposed a simplified LCA-based tool to assess the environmental impact of garments for routine usage by fashion designers. Critical elements extracted from the comprehensive LCA of knitted jumpers were utilised to devise a simplified data table. The data table showed a simplified approach for developing a tool that can instantly assess the environmental impact of garments. Along with the data table, the study presented a "Simplified LCA framework for Fashion Design," that lists ten foundational processes which serve as a blueprint for programming the envisioned assessment tool.

Third, this research provided valuable lessons for the fashion design community venturing into the scientific realm of LCA. The interdisciplinary nature of this research underscores the significance of collaboration, continuous learning, and adaptability in overcoming the challenges in academic endeavours.

This study deepens our knowledge of garment life cycles. It offers practical guidance on data collection, its validity analysis, and impact assessment for comprehensive life cycle assessments. The study examined the environmental impact of natural and synthetic materials and three major knitwear manufacturing techniques in both local and global supply chains. The primary data collected by an extensive survey in New Zealand for the use and end-of-life phases of knitted jumpers enabled a more precise estimation of their cradle-to-grave impacts. The simplified LCA-based approach will empower fashion designers to factor life cycle thinking into design processes, leading to informed decisions. In conclusion, this thesis encourages fashion designers to embrace ‘reckoning’ in conjunction to reduce, reuse and recycle, the fourth “r” for sustainability in fashion design.