From Animals to Humans, Insulation Explained

22 February 2022

Manasseh Franklin

During long stretches of dark, cold winter days, I often think of wildlife and wonder: how do they stay warm with only their fur? As a human, I am useless––and literally prone to death by cold––without the comforting warmth and protection of winter clothing.

But the way animals stay warm in winter is not so unlike the way humans do. There’s a reason, after all, that for centuries humans have called on animal insulation like wool, hair, feathers and even whale intestines to keep us warm. Whether a polar bear in the arctic, sheep on the highlands of New Zealand or goose on a lake in Central Park, animals––like humans––need an essential advantage to combat cold temps: a little thing called insulation.

The physiology factor

Pop quiz: What's the biggest difference between a fox and a lizard?

Answer: They’re different species, of course, but for our purposes, the most significant difference is the kind of blood they have––warm for the fox, cold for the lizard. How animals (including humans) get and stay warm is based on the temperature of their blood.

Cold blooded creatures rely on outside temperatures to warm or cool them. This is why you see small amphibians like lizards in hot places like the desert and rarely in cold places like the Arctic–––if there is not enough ambient warm air and their blood gets too cold, they die. (Some frogs have actually adapted to where their blood can freeze and they don’t die, but that’s another, fascinating story.)

Warm-blooded creatures on the other hand need to maintain a specific internal body temperature regardless of outside ambient air temperatures. For humans, that’s 98.6ºF. In the warm-blooded animal kingdom, it ranges from 97-103ºF degrees with some birds needing to maintain 105ºF.

Therein lies the key ingredient, insulation, which prevents that valuable body heat from escaping into the cooler air outside and helps warm-blooded bodies stay well, warm and alive.

Arctic Fox

How insulation works

“Insulation traps air to capture the body’s natural convection,” explains LifeLabs’ Senior Scientist Cindy Lau. “Still air is a very good insulator, as opposed to air that’s moving, which takes away your heat. Most insulations are puffy because they need to be able to trap air.”

In the world of warm-blooded creatures, insulation comes in the forms of fat or blubber, hair, wool and feathers. (Blubber does not work by trapping air but instead forms a thick under-skin layer that prevents body heat from escaping and provides energy the metabolism burns to stay arm). No matter the material, the purpose is the same: trap the body’s infrared heat to keep blood temperature stable.

Snowy owls

Some animals, like the polar bear, rely on a three-layer insulation system. First, there’s a thick under-skin fat. Next, a layer of fur or down feathers packed tightly against the skin with room for air pockets. Last, oily, water-repellent guard hairs or feathers that are sometimes transparent or hollow. Polar bears have such an effective insulation system that when viewed with heat-seeking night vision goggles, the animals don’t show up. This is because their outer fur is the same temperature as the ambient Arctic air.

This 3-part system, comprising a next-to-skin layer followed by air-trapping insulation layer, topped off with a protective outer layer, should sound familiar. It's the basic ingredients of most winter apparel layers for humans. It’s also the system we’ve created with our MegaWarm Jacket––breathable inside fabric, down insulation, PFC-free outer shell.

Fun fact: When humans move between ambient temperatures, like from a warm house to the cold outside winter air, the blood in our bodies moves from the extremities––feet, hands, arms, legs––to the torso to protect vital organs. Keeping your torso warm is always the body’s first priority, and part of why vests like the WarmLife vest are such a useful winter layer for humans.

Types of insulation

Animals are such distinct models of effective insulation, humans have long relied on them for actual insulating materials, or inspiration to create our own. Throughout history, we’ve used buffalo hides, seal skins, and beaver pelts, to name just a few. These days, the most common and culturally acceptable animal-based insulators are wool and down, which can be harvested repeatedly without harming the animals (though there are more and less harmful ways).


Wool’s curly fibers are a favorite in the natural insulation realm. Wool offers excellent temperature regulation, breathability, and it stays warm when wet. It is expensive, though, and has a lower warmth to weight ratio than other insulators.

Wool insulation

Down feathers

Gathered from the under feathers of geese and ducks, down insulation has a unique structure that allows it to trap air better than any other insulator. It has a high warmth to weight ratio, can be compressed without losing its loftiness and if cared for, lasts a very long time. It is pricy though, and notably less breathable than synthetics.

Down feathers can be harvested in a variety of ways. Certifications like the Responsible Down Standard (RDS), Traceable Down Standard and International Down Standard help consumers to choose ethical down products. In MegaWarm, for instance, we only use down sourced from RDS certified suppliers.

Synthetic insulation

Synthetics are an ever-expanding category of insulation. Perhaps you’ve heard of Polartec or PrimaLoft. Regardless of name, the basic principles are similar: trying to create a layer that traps air but maintains an attractive warmth to weight ratio. Unlike down, synthetics can maintain warmth when wet (down will flatten and get soggy, thereby losing its air-trapping properties).

Fleece is another kind of synthetic insulation that utilizes a brushed surface to trap air. Its high level of breathability is a double edged sword, since that makes it more permeable to wind. It is also made predominantly of polyester, which is a known contributor to microfiber pollution .

Aerogel is a silica with very small pores to trap air. “It’s effective if you’re in outer space,” says Cindy, referring to synthetic’s primary job of outfitting astronauts, "but not as effective in real life applications. When you need to incorporate aerogel in fabric, you end up making it heavy because it needs carriers.”

LifeLabs’ approach to insulation

“We always try to tackle warmth to weight,” Cindy says about LifeLabs innovation process. “We want to be efficient.”

Optimizing warmth to weight requires fewer materials. “In the case of MegaWarm, not only are we making use of the best trapping insulator which is down, but we’re elevating it to another level with our WarmLife technology. Down is not cheap; if we are able to elevate its performance in terms of sustainability and materials, we can maximize efficiency.”

MegaWarm jacket

In a class all its own, WarmLife doesn’t draw off of any particular animal inspiration. But the reflective technology harnesses your body heat and reflects it back to you, thereby mirroring the effect of other kinds of insulation without the bulk that’s characteristic of virtually all natural and manmade materials.

We can think of it as the start of a new insulation frontier.