Case Study Of Fast Fashion And Sustainable White Cotton T-Shirts : A Comparative Life Cycle Assessment

Sammanfattning

The global fashion industry is a major contributor to greenhouse gas emissions andresource use, yet it is often overlooked in energy transition discussions. Fast fashion, inparticular, relies on fossil fuel–heavy supply chains and promotes overconsumption, leading to high environmental costs. This thesis presents a comparative Life Cycle Assessment of two white cotton t-shirts: one from fast fashion produced in India, and another manufactured sustainably in France. Using a cradle-to-grave system boundary and ISO 14040/44 methodology, the study evaluates energy use and greenhouse gas emissions across all life cycle stages. The functional unit is 100 wears, allowing a fair comparison based on garment longevity. The primary data was drawn from the Ecobalyse simulator and supporting literature. Hotspot and comparative analyses were conducted to identify the most impactful stages and key differences between the two production systems. The fast fashion t-shirts consume five times more energy and emit over ten times more CO₂ than the sustainable shirt over a 100 wears. Major hotspots included the use phase (washing and drying), wet processing, and international transport. The fast fashion model shows even higher impacts due to the need to produce four shirts to match the lifespan of one durable garment.This case study concludes that product lifespan, local production, and cleaner energy grids significantly reduce a garment’s environmental impact. While the study is limited by the exclusion of water-related and social indicators, it offers significant insight into the hidden costs of everyday clothing and provides evidence to support a transition toward more responsible practices in the fashion sector.