Sustainable Insulation for Winter Clothes

Common eider nest
Common eider nest, with down. Arctic-Images/Corbis Documentary/Getty

When selecting winter wear, our concerns usually are about how warm a piece of garment is, how expensive it is, and let’s face it, whether it is fashionable. Another factor should be part of our decision-making: how green is the insulation? There are many types of insulation materials, each with a different environmental footprint. There is no single material which can clearly be deemed most environmentally friendly, but here is some information about insulation material sustainability which will hopefully help you make the right decision for you.

Sustainable and Ethical Down?

Insulation down is made from the small fluffy feathers found underneath a bird’s quilled feathers. Down’s role is one of, no surprise, insulation. Down is particularly sought after as it has a very advantageous warmth to weight ratio and it maintains its loft, trapping warm air close to the body even after years of use.

Down is usually obtained from the breast of geese and ducks after they have been slaughtered for food. However, there is evidence of some eastern European and Asian farms harvesting breast down feathers directly from live ducks, which then regrow the feathers. This inhumane method is painful to the bird, and many garment companies are trying to distance themselves from those live-plucking practices.

Some large outdoor clothing manufacturers have established sustainable sourcing practices to ensure their down is produced ethically. For example, outdoor clothing giant The North Face is expecting that by the end of 2016 all of the down it uses will be obtained ethically through their in-house Responsible Down Standard certification. Outdoor clothing manufacturer Patagonia has a similar program called Traceable Down which sources down from farms where the waterfowl are not live-plucked. Patagonia also offers jackets and vests made with recycled down obtained from used comforters and pillows. The feathers are sorted, washed, and dried at high temperature before it is sewn into new products.

Goose and duck down is a product with great insulation properties, but the very lightest and warmest down is grown by a sea duck found in the frigid waters of the North Atlantic and Arctic Oceans: the common eider. Eider down is obtained from wild birds, but not the usually way by plucking it directly from the duck. The eiders use their own down to line their nest, and trained harvesters visit nesting colonies where they pick up a portion of the down feathers found in each nest. This sustainable practice has no negative effects on the eiders’ nesting success, but it yields only about 44 grams of down on average per nest, and much less once it’s sorted and cleaned. Eider down is of course very expensive and is used mostly in high-priced comforters and luxury clothes.


Wool is a product with excellent insulation qualities, as it remains warm when wet. It has been used for centuries, and while its popularity declined after the development of synthetic products, wool is making a comeback in outdoor apparel and fashion wear. Merino wool in particular is sought after for its softness and wicking properties. A sustainability certification program, named ZQ, exists for wool from New Zealand Merino sheep.

By definition wool is a renewable resource, but in reality the sustainability of wool is as good as the farming practices used to raise the sheep. Pastured sheep efficiently convert energy from grass with relatively little greenhouse gas emissions as compared to cattle. In more arid regions, overgrazed rangeland is often an unfortunate sight. Farmers markets can present a good opportunity to get to know sheep farmers and their practices. The markets are also a good place to meet farmers who raise alpaca, a relative of the llama known for its high quality wool.

A Synthetic Solution?

While synthetic insulation is not quite as warm as down, it has the significant advantage of not holding water and not losing its insulation value when wet. Unfortunately, synthetic insulation is made from oil byproducts in a process releasing significant greenhouse gases. To get around that, the main synthetic insulation makers offer versions of their products made, partly or wholly, of recycled materials. For example, PrimaLoft and Thinsulate offer recycled alternatives, and Patagonia produces fleece fabric spun from PET plastic (#1) recycled from soda bottles.  

Unfortunately there is increasing evidence that polyester, which makes up most of the fibers used in synthetic insulation, has a water pollution problem. Every time a polyester garment is washed, tiny fibers get detached and washed down the drain. The fibers will not decompose the way cotton or wool would. Instead, polyester fibers are being found in bodies of water all over the world. There, the fibers contribute to the global microplastics pollution problem: persistent organic pollutants stick to the fibers’ surface, and aquatic microorganisms then suffer from ingesting them.


Yes, milkweed! Asclepias has long been known for its insulation properties, and has been used as a hypoallergenic pillow fill. Figuring out how to use it for clothing insulation has proven elusive until recently when a Canadian company developed a lightweight, effective-when-wet, very warm woven fabric made from milkweed. For now, it comes in limited applications and at a steep price, but as a bonus the commercially grown plant is only harvested after it has served as food for the monarch butterfly larvae.

Make It Last!

The most environmentally sustainable insulated garment is the one you don’t buy, so make the clothes you own last a long time. Knowing how to make basic repairs, like replacing a zipper or mending a tear, can stretch the functional life of a jacket for several more years. Purchasing quality clothing well-constructed by a reputable manufacturer in the first place pays off in the end, as it will likely last much longer than discount brands or cheap knock-off products.