TCF POST Report
Natural fibres are not automatically greener than synthetics, while extending garment life could deliver some of the fastest environmental gains, researchers find. A new review of the environmental sustainability of textile fibres challenges the increasingly common assumption that natural fibres are automatically the greener choice, finding that the environmental cost of a garment depends on the entire life cycle—from cultivation and fibre production to manufacturing, washing, use and disposal.
The review, published in Encyclopedia, compares natural and synthetic fibres across carbon emissions, energy and water consumption, resource use, microplastic pollution and end-of-life pathways. The authors are Sayam, Tarikul Islam, Sakil Mahmud and Subrata Chandra Das, with researchers affiliated with Barishal Textile Engineering College, Jashore University of Science and Technology, the University of Georgia, Lincoln University, Daffodil International University and the Norwegian University of Science and Technology.
Cotton’s water burden stands out
One of the starkest findings concerns cotton. The review reports cotton’s water requirement at about 6,238–8,920 litres per kg of fibre, alongside GHG emissions of around 8.3 kg CO₂ equivalent/kg and energy demand of 68.5 MJ/kg. Its major environmental hotspots are intensive irrigation and agrochemical use.
By comparison, several alternative natural fibres show substantially lower reported environmental burdens. Jute is listed at 0.58 kg CO₂ equivalent/kg, kenaf at 0.55 kg, coir at just 0.367 kg, and banana fibre at 0.48 kg. Coir’s reported water use is 2,320–3,100 litres/kg, while hemp is reported at only 300–500 litres/kg.
But the review stresses that even these figures cannot be treated as universal rankings. Climate, irrigation, agricultural practices and processing technologies can substantially change environmental performance. Bamboo, for example, has a reported emissions range of 0.55–4.02 kg CO₂ equivalent/kg, depending on processing methods.
The synthetic-fibre problem shifts from production to pollution
Synthetic fibres present a different set of risks. Nylon has reported emissions of about 20 kg CO₂ equivalent/kg, compared with a polyester range of 2.3–14.2 kg. Elastane is reported at 15–20 kg CO₂ equivalent/kg, while carbon fibre can reach 19.29–24.83 kg CO₂ equivalent/kg.
Perhaps the most striking synthetic-fibre finding concerns microplastics released during washing. The review reports that polyester can release approximately 56–378 microplastic fibres per gram per wash, while polyethylene can reach 1,900 fibres/g per wash. Nylon is reported at 331 fibres/g per wash, while acrylic can release 146–227 fibres/g per wash.
This means the environmental impact of a synthetic garment does not end when it leaves the factory: its use phase can continue releasing persistent fibres into wastewater systems.
Polyester tells a surprisingly different life-cycle story
The review also finds a major difference between cotton and polyester garments in terms of where their environmental burdens occur. For cotton T-shirts, the use phase accounts for much of total energy use and global warming impact, while for polyester jackets approximately 71% of total energy consumption is associated with production, compared with about 26% for cotton products. For 65% polyester/35% cotton shirts, the use phase can account for about 64% of total energy consumption, with manufacturing contributing around 36%.
A cotton T-shirt, for example, is estimated to consume about 109 MJ of energy over its life cycle, with approximately 65 MJ occurring during the use phase. For jeans and khaki trousers, washing and other use-stage activities can represent roughly 58–63% of total life-cycle energy consumption. That makes consumer behaviour a significant sustainability variable. The review notes that reducing a washing cycle from 60°C to 30°C can save about half the energy required, while line drying eliminates the electricity demand of tumble drying.
Recycling alone is not the whole answer
The researchers point to another major contradiction in textile sustainability: recycling can reduce environmental impacts, but the system remains difficult to scale because of blended fibres, chemical finishes, collection problems and consumer disposal behaviour.
Recycled polyester demonstrates the potential. The review reports that producing recycled PET can reduce GHG emissions by approximately 30–50% compared with virgin polyester, with reported emissions as low as 0.737 kg CO₂ equivalent/kg. However, the benefits depend on collection efficiency, material purity and the energy required for reprocessing.
The study therefore identifies longer product life, reuse and repair as among the most immediate opportunities for reducing textile environmental burdens. Reusing one tonne of cotton garments can save approximately 64,951 kWh of energy, while reuse of one tonne of polyester garments can save about 89,811 kWh.
Natural fibres show major potential beyond apparel
The sustainability argument extends beyond clothing. Natural fibres can also replace more energy-intensive reinforcements in composite materials used in automotive, construction and other applications. Flax-reinforced composite systems can require as little as 6.5 MJ/kg, while carbon-fibre systems can require 183–286 MJ/kg. The review reports around 0.90 kg CO₂ equivalent/kg for some flax systems versus about 29.4 kg CO₂ equivalent/kg for carbon-fibre composite systems.
The energy advantage also appears in manufacturing: preparing flax-fibre mats can require about 50% less energy than preparing comparable glass-fibre mats. In automotive interior applications, flax and flax-recycled-polymer composites have been found capable of similar weight savings to glass-fibre composites while reducing life-cycle energy requirements by about 20%.
Jute also emerges as a potentially important material. In composite applications, the review reports jute at 9.6 MJ/kg energy intensity and 1.3–1.9 kg CO₂ equivalent global-warming impact, compared with 183–286 MJ/kg and 26.4 kg CO₂ equivalent for carbon fibre.
The industry’s sustainability target may need to change
The review’s central message is that there is no universally sustainable fibre. Natural fibres bring renewable feedstocks, potential carbon sequestration and biodegradability, but can involve substantial water, land and chemical inputs. Synthetic fibres offer durability and consistent performance but rely heavily on fossil resources and create challenges around emissions, microplastics and end-of-life waste.
The authors argue that sustainability claims should therefore be assessed according to the specific product, application and life-cycle conditions, rather than assigning a blanket environmental label to an entire fibre category.
For the textile industry, that shifts the focus from simply replacing polyester with natural fibres toward a broader strategy: cleaner agriculture, low-impact processing, recycled and bio-based materials, durable product design, repair, reuse, resale and better material recovery.
The review also highlights lower-impact production technologies such as supercritical CO₂ dyeing, digital printing and foam finishing, which can reduce water, chemical use and wastewater compared with conventional wet processing.
The most important implication for fashion may therefore be simple: the greenest garment is not necessarily the one made from the “greenest” fibre—it may be the garment that is made efficiently, worn for longer, washed less intensively, repaired, reused and ultimately recovered.