Now that spring has sprung, bringing with it sunny days and a sunnier outlook, it’s fair to say that stuffing made the previous months of below-freezing temperatures and dark, damp days tolerable. Not the edible stuffing found in turkey or cooked in dough: the thermal stuffing found in jackets, sleeping bags, and bedding. 

But are the products that are keeping you warm leaving the planet out in the cold? The Decider is here to help you choose thermal insulation that protects you and the planet from harmful elements.

Most thermally insulating products, like winter jackets and sleeping bags, consist of two main components: an inner filling and an outer shell. 

The filling is made from either down—a naturally insulating material made from the small, fluffy feathers found on the underside of waterfowl—or synthetically derived fibres that mimic it. Both types of filling create insulation by trapping heat in the air pockets between clusters of feathers or fibres. 

The outer shell is predominantly made from synthetic fibres such as nylon, polyester, and sometimes Gore-Tex, since these are lightweight, durable, and water-resistant (hydrophobic). The shell is often chemically treated to strengthen its water resistance. Durable water repellent (DWR) is a common hydrophobic fabric treatment.

Forever yours

Down is lightweight and easy to compress, so it can provide the same amount of insulation as synthetic fill while weighing less. An important property of down is its fluffiness, otherwise known as “loft” or “fill power.” This figure measures the volume that is filled by a specific weight of down. In North America, it’s typically calculated as cubic inches per ounce and ranges from 300 to 1,000. A high loft number indicates that the down will provide more volume—and by extension more warmth—at a lighter weight.

However, unlike its synthetic counterparts, down can clump and lose its insulating properties when it gets wet. To make it more water-resistant, manufacturers sometimes treat it with wax, silicone, or perfluoroalkyl and polyfluoroalkyl substances (PFAS). 

PFAS’ very slow rate of biodegradation means that they tend to accumulate in both humans and the environment, earning them the nickname “forever chemicals.”

PFAS are a class of synthetic chemicals widely used in commercial goods due to their ability to repel oil and water. However, their very slow rate of biodegradation means that they tend to accumulate in both humans and the environment, earning them the nickname “forever chemicals.” Because of their detrimental effects, PFAS are now widely viewed as environmental contaminants. 

The good news is that more and more companies are using alternative methods to make their products—inner down and outer shells—hydrophobic. These methods leave them free of PFAS, including subclasses known as PFCs (perfluorinated compounds), PFOSs (perfluorooctanesulfonic acid), and PFOAs (perfluorooctanoic acid). 

Dr. Patricia Dolez, an associate professor in the University of Alberta’s Human Ecology department, says there are good solutions for both fillings and shells that are not based on PFAS or their variants. “They are using silicones, they are using waxes, and they do a good job.” 

The down-low

The bad news is that companies can be opaque about the exact methods they use to make their down hydrophobic. This makes it difficult to know if they are environmentally friendly. For example, while wax-coated down can biodegrade, silicone-coated down cannot.

If you’re opting for a down-based product but are concerned about unsustainable chemical treatments, you can look for a “bluesign-certified” label. The Swiss company bluesign technologies works with brands to ensure a sustainable textile supply chain, with emphasis on sustainable chemistry. It bestows its bluesign-approved certification on products where 90% of an item’s fabric and at least 30% of its accessories meet its criteria. Some common brands of hydrophobic down, such as Nikwax Hydrophobic Down, Allied Feather + Down’s HyperDry, DownTek, and Marmot’s DownDefender, are all bluesign partners.

Even if you use recycled fibres, if the products are coming from the other side of the world, maybe it’s not a very sustainable process or system.

Another concern you may have about down is whether it is sourced responsibly. Down is a byproduct of the meat industry: the feathers are plucked from geese and ducks being raised for meat and eggs. Animals in industrial meat farms are often overfed and subjected to crowded, inhumane conditions. If you care about this aspect of down, look for products with either the Responsible Down Standard (RDS) or the Global Traceable Down Standard logo. Both of these allow brands to source their down from certified farms whose birds have not been subjected to live-plucking, force-feeding, crowded living conditions, disease, discomfort, or distress. 

Other options are to buy products made with recycled down—which is typically collected from used bedding such as pillows, duvets, and mattresses—and to use down-tracking websites like the ones offered by Sustainable Down Source and Allied. These sites allow you to use the lot number of the down in your product to learn more about where it came from. 

Polyester predicaments

If you want to forgo animal products entirely, you can opt for a synthetically derived thermal-insulation material instead. You have many options to choose from, such as PrimaLoft, Thinsulate, Climashield, and Polartec. Many prominent winter-gear companies are even developing their own proprietary thermal-insulation materials—for instance, ThermoBall and Ventrix by The North Face, FullRange by Patagonia, and Coreloft by Arc’teryx. 

However, as noted above, most of these materials are primarily derived from polyester, whose fibres are made from plastic pellets, which in turn are derived from crude oil. This process is immensely environmentally taxing, requiring anywhere from 5,000 to 7,000 cubic metres of water to produce 1 kg of polyester fibres. In addition, polyester releases microfibres into the environment when it’s washed, reportedly takes anywhere from 20 to 200 years to biodegrade, and releases greenhouse gases into the environment from landfills.

Given this extreme environmental toll, companies are increasingly using recycled polyester to make both the filling and shells of their products. Recycled polyester is primarily made from plastic bottles rather than fabric products, because, as U of A’s Dolez notes, “most of our clothes are not one material.” For instance, she says, polycotton is a mix of polyester and cotton. “So, to recycle one of them, you need to remove the other one.”

Companies can be opaque about the exact methods they use to make their down hydrophobic.

However, as Dolez points out, “Even if you use green fibres, sustainable fibres, [or] recycled fibres, if [the products] are coming from the other side of the world, maybe it’s not a very sustainable process or system.”

In fact, the greenhouse gas emissions generated from shipping mean that products made overseas usually have a greater environmental cost. They are also more likely to have a serious human cost, as many manufacturing companies in less regulated countries exploit their workers, overworking and underpaying them and subjecting them to unsafe working conditions. 

You can minimize both costs by opting for brands that manufacture locally; Wuxly and BEDI Studios, for instance, are two brands that manufacture winter jackets in Canada. You can also research brand websites to gauge how transparent they are about their supply chain. Some good signs are partnerships with nonprofits dedicated to improving environmental and worker conditions, sustainability reports, and labels such as Fair Trade Certified.

Shell game

Still, even if you manage to buy a locally made jacket or sleeping bag filled with recycled down, its outer shell will almost certainly be made of a synthetic material like polyester, nylon, or Gore-Tex. This is because natural fibres like cotton, linen, and silk simply cannot be treated to be as durable and hydrophobic as synthetics. 

Dolez acknowledges that there are some items where you’ll have a hard time finding a material that works better than polyester or nylon. In these cases, she advises, “Find it secondhand.” This way, she says, you can give the product a second life instead of creating demand for virgin synthetic fibre. You can extend its life even further by keeping the item for a long time and repairing it when it breaks down.

The decision

If you want a thermal insulation material that is naturally derived and biodegradable, opt for down. If you’re not keen on animal-derived products, opt for polyester. 

While synthetic materials are largely unavoidable in the outer shells of thermal-insulation products, you can mitigate their environmental cost by shopping local and/or secondhand; making sure that their inner filling—whether down or polyester—is responsibly sourced, recycled, and not treated with PFAs; and keeping them for a long time.

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