Autumn is just around the corner for many of us and winter wardrobes are waiting in the wings. But have you ever considered the environmental impacts of layering up?
Wool is an essential winter staple: insulating, soft, breathable. However, it emits more carbon than plastic fibres like polyester, acrylic, and polyurethane.
Here are some animal wool alternatives that can keep us toasty without warming the planet.
The impact of wool
Wool is one of the oldest textiles. Archaeological finds indicate that it’s been in use since 10, 000 BCE.
Like many material products of evolution, wool is hard to beat when it comes to protecting us against the elements. The fine structure traps air pockets to prevent heat from escaping. It is also easy to fine-tune, offering fibres that vary for different degrees of texture and warmth.
In a world where oil plastics dominate clothing textiles, wool also stands out for its biodegradability. This is a plus for the environment, since any discarded wool that ends up outside poses far less of a toxicity threat to wildlife than polyester, acrylic, or other plastic materials.
However, the material is also incredibly resource intensive to make. Shockingly, the carbon dioxide produced per kilogram of wool is double that of polyester, which is based on fossil plastics. Wool also emits higher carbon than acrylic and polyurethane – in fact, it usually tops the list when it comes to carbon-emitting textiles.
This makes sense when we consider how livestock is a significant contributor to global warming, accounting for more than half of total global agricultural emissions. Wool is no exception. The carbon emissions of wool production come from the burps and farts of sheep.
Around 1 million tonnes of wool is made each year. Replacing some of this with more environmentally friendly options is now easier, with a diverse range of wool alternatives made from less impactful feedstock.
Coconut and hemp wool from Colombia
The fashion industry needs more planet-friendly winter warmers. In Colombia, a group of university students have heeded the call, developing a coconut-hemp wool alternative that won the PETA prize for animal-free wool in 2018.
The material goes by the name Woocoa and can be knitted just like sheep’s wool.
The material is sustainable on many different levels. Not only could it displace the need for carbon-intensive livestock fibre, it is made from waste rather than crops specifically for textile manufacturing – medical marijuana waste, to be precise. This keeps the impacts of the material down, especially when it comes to agricultural fertiliser pollution and water usage.
The material results from a sophisticated biomanufacturing process that gets rid of harmful processing chemicals – it is produced using enzymes from oyster mushrooms.
The material has some of the properties of wool that are difficult for synthetic fibres to fully mimic. For example it is naturally antimicrobial and wicks away humidity.
Clothing is just one application for the wool alternative. These strong fibres can also be used in water filtration equipment or as biodegradable packaging.
Wool from the sea
Taiwanese startup Creative Tech Textile found inspiration for a sheep-free wool in farmed oysters.
Using discarded oyster shells from the aquaculture industry, as well as recycled plastic waste, the developer has come up with a circular fabric to create a soft, wool-like fabric known as ‘Seawool’.
Just like sheep’s wool, the fabric comes with a naturally low heat conductivity. This means it does not draw heat away from your body while wearing it, ensuring you stay warm.
One reason why the material is able to mimic the heat-insulating properties of sheep wool is the structure of its surface – marked with tiny scales that come from powdered oyster shell. The rough micro-textures distinguish it from synthetic polyester, a common wool substitute in the clothing industry.
Since 2022, the company has used up 100 tonnes of oyster shells as well as 20 million PET bottles in its wool production. Every time the company reaches for this waste feedstock, it means that much less need to draw on damaging virgin materials like sheep’s wool or new plastic fibres.
The material is already a hit with knitwear producers. English clothing brand Albert and Maurice has adopted Seawool and turned it into autumn/winter menswear jumpers. Josephine and Co have a womenswear collection that uses the material.
The company has also developed Smawarm, a highly insulating material designed for gloves, down jackets, bedding, and sleeping bags. This shows how these circular wool alternatives serve outdoor applications that demand the highest levels of insulation.
Scottish mussel beard fibres
Britain may soon be getting its own line of wool sourced from the sea. Scottish startup Seastex is turning to mussels to create multi-functional fibres that could be used in anything from construction to design.
Seastex’s feedstock are the ‘beards’ of the mussel. These are the inedible bunches of thread-like fibres that allow mussels to truss themselves to surfaces like rocks. Mussel farmers cut and discard the material off while harvesting.
The team is already securing access to around three metric tonnes of the stuff every week and has built a prototype and production line. For now, the target market is construction and interiors where the bulky fibres could fill a niche in sustainable upholstery and soundproofing.
Like Taiwan’s Seawool, this Scottish mussel fibre wool does not put pressure on human food sources, since the feedstocks are all byproducts of the food industry rather than crops that could have gone on to be eaten. This enhances the sustainability of the final product.
A plant-based wool from India
Back on land, plants can also offer feedstock for warm wool-like substitutes.
Indian fashion entrepreneur Gowri Shankar has a poetic story about how he got the idea behind his plant-based wool brand Weganool, which takes material from the wild flowering shrub Calotropis.
One day, he was staring outside the window one afternoon when he noticed birds plucking fibres around a Calotropis bush for a soft, yarn-like material they used in their nests. It sparked the idea that he could use the plant to make clothing textiles.
Weganool’s vegan wool uses 30% Calotropis fibre and 70% organic cotton. The plant is suited to substitute for animal wool because its fibres are hollow inside, making it capable of trapping heat.
Calotropis, commonly known as milkweed, is a hardy plant that moves quickly into areas of barren soil that other plants cannot thrive in. Like the oyster shells and mussel fibres that go into Seastex and Creative Tech Textile’s products, this hardiness makes milkweed a sustainable material – it does not put pressure on human food supply because it can be grown on poor soils that would not support food crops. It also requires few inputs like pesticides and watering.
Brewed wool from Japan
One emerging manufacturing tech that promises to take the sheep wool substitutes to another level is precision fermentation. This technique uses industrially reared, custom-engineered to produce any biological chemicals – whether food ingredients, medicines, or the kinds of proteins found in animal fibres.
In a process that is similar to fermenting beer or cheese, chemicals with specific properties can be produced at scale, consistently.
Japanese company Spiber is the leader in precision fermented textile fibres. It produces what’s called Brewed Protein from sugarcane, a fibre that can be refined into many different kinds of textiles. Spiber’s Brewed Protein remains the only precision fermented protein fibres available on an industrial scale.
Technically, Spiber’s Brewed Protein is synthetic in the sense that it is created in a laboratory. Yet it mimics the protein-rich fibres we find in fur and hair through the animal kingdom, making them eminently biodegradable.
In 2022, Spiber conducted a study into how sustainable its Brewed Protein actually was. It did this by analysing the environmental impact of its fibre against typical cashmere and wool production. The analysis found that Brewed Protein had lower impacts than on greenhouse gas emissions, water scarcity, and eutrophication (nutrient pollution of waterways from agriculture).
Spiber is trying to draw out the full spectrum of its material’s properties through collaborations with industry. In the field of warm clothing and knitwear, the brand has been working in particular with luxury Italian textile mills.
In 2025, Spiber announced a strategic partnership with Manifattura Sesia to create a new yarn line that mixes 30 percent Brewed Protein and superfine merino wool. The advantage of blending natural wool with the protein fibre is that it produces a yarn that is soft and more lightweight than pure wool. Alongside the comfort factor, it also cuts back on the environmental impacts that come with material taken from livestock.
In 2024 came a collaboration with Baruffa Lane Borgosesia, an Italian wool mill. The partners have been experimenting with spinning techniques that blend Brewed Protein (30%) with merino wool (70%).
Spiber’s Brewed Protein is also holding its own as a complete wool substitute without blending. The Italian wool mill Botto Giuseppe sells a range of 100% Brewed Protein worsted yarn in diverse colour options.
Spiber’s work with industry would finally pull the R&D limelight onto sustainable wool. In fashion, wool fibre has received less attention than leather when it comes to developing vegan manufacturing pathways.
Wool fibre is an incredible natural material. Now, we can mimic its warmth and flexibility with diverse sustainable feedstocks. The high-tech luxury of Spiber’s brewed yarns are just starting to hit high-end fashion while circular options that tackle seafood waste show us how we can do more with less. Sweater season now comes with a sustainable conscience.