How Can Down Keep You Warm?

As winter approaches, the days become shorter and temperatures decrease. Whether it’s putting on a coat filled with down feathers or snuggling under a down comforter, we often have birds to thank for the warmth we experience. Have you expressed your gratitude to a bird recently?

That’s correct! We owe birds our thanks for the material we call “down” that is stuffed inside coats, sleeping bags, comforters, and pillows. Down refers to the fine feathers that many birds have underneath their outer feathers.

However, it may seem odd. If bird feathers are so warm, why do many of them migrate south for the winter? As it turns out, most birds migrate in search of food, not because they are cold.

Down feathers are excellent thermal insulators. The loose structure of down feathers traps air.

Consequently, heat cannot easily pass through down feathers. This means that birds are insulated from the cold air outside, and their body heat does not escape easily either.

Human beings discovered the insulating properties of down feathers long ago. For instance, documents from the 1600s indicate that Russian merchants sold “bird down” to the Dutch hundreds of years ago.

Today, down is used in various products, including coats, bedding, and sleeping bags, to provide better insulation against cold weather. Down can be obtained from various types of birds, but most of the supply nowadays comes from domestic geese.

About 70 percent of the world’s down supply comes from China. Most of the down is obtained from birds that are killed for their meat. A significant amount of down also comes from Europe and Canada.

In the United States and Europe, it is illegal to pluck down from a live bird. However, live-plucking is known to occur in Poland, Hungary, and China. Animal welfare organizations continue to fight against the practice of live-plucking wherever it is found.

If you own a down coat or comforter, is it entirely made of down? In the United States, laws require that products labeled “100 percent down” only contain down feathers.

If a product is labeled “down,” it can contain a mixture of down feathers and synthetic fibers. However, not all down feathers are of the same quality.

Down insulation is rated based on a measure called “fill power.” The higher the fill power, the better the insulation provided by the down.

The highest fill power rating, 1200, is given to eiderdown, which is obtained from the Common Eider duck. Eiderdown tends to be expensive.

However, don’t worry. Down with half the fill power rating of eiderdown still offers good insulation against the cold.

In addition to being warm, down is also lightweight and durable. If taken care of properly, down lasts longer than most synthetic fibers. However, when it comes to down, it does have one disadvantage (pun fully intended).

If down feathers get wet, their thermal insulation properties basically disappear. When exposed to moisture, down feathers clump together and become mildewed.

If not dried properly, mildewed down will start to have an unpleasant odor. So be sure to keep your down products dry!

Give It a Try

Are you ready to experience the benefits of down? Make sure to explore the following activities with a friend or family member:

  • It can be expensive to stay warm in the winter. Heating a house and keeping it warm all winter requires a lot of energy. However, there are things that you and your family can do to make your home more energy-efficient in both winter and summer. You can try some of these ideas to make your home more comfortable while also saving money and conserving energy:
    • When you leave a room or finish using an electrical appliance, make sure to turn it off.
    • Experts recommend setting your thermostat to 68°F (20°C) in cold months and 78°F (26°C) in hot months. By keeping your thermostat at a lower temperature in winter and a higher temperature in summer, you can save energy and money.
    • Think green! Throughout your daily routine, think about ways you can reduce energy usage. Every small step you take can make a difference.
  • Ask an adult to take you on a field trip to a local clothing store. Explore the different types of coats they have. Can you find any down jackets? What other materials are commonly used in coats? If possible, compare the look and feel of down jackets with those made of other fibers. Do you notice any differences in how warm they feel?
  • Do layers of clothing really help keep you warm? Find out by conducting the Insulation Experiment: Keep Your Body Warm. You will need various types of materials and assistance from a friend or family member. Share your findings with friends. Were you surprised by the results of your experiment? Why or why not?

Wonder Sources



1. How can down keep you warm?

Down is a natural insulator found underneath the feathers of birds, such as ducks and geese. Its structure consists of tiny filaments that trap air, creating pockets of warmth. These air pockets prevent heat loss by acting as a barrier between your body and the cold air outside. The more down in a garment or bedding, the better it will insulate you. Additionally, down is highly breathable, allowing moisture to escape and keeping you dry and comfortable.

2. What makes down a good insulator?

Down is an excellent insulator due to its high loft and ability to trap air. The loft refers to the thickness and fluffiness of the down clusters. The higher the loft, the more air is trapped, and the better the insulation. Down also has the advantage of being lightweight, making it an efficient insulator without adding bulk. Its natural properties make it an ideal choice for cold weather gear, as it provides exceptional warmth while allowing for freedom of movement.

3. Can down keep you warm in wet conditions?

Unlike synthetic materials, down can lose its insulating properties when wet. However, treated down or down with a water-resistant outer shell can still provide some warmth in moist conditions. Treated down is coated with a durable water repellent (DWR) finish, which helps repel moisture and maintain its loft. It’s important to note that even with treated down, prolonged exposure to wet conditions can eventually affect its insulation. Therefore, it’s advisable to use a waterproof shell or layer when wearing down in wet environments.

4. Is down suitable for all climates?

While down is an excellent insulator, it may not be suitable for extremely hot or humid climates. Down is designed to trap and retain body heat, which can be uncomfortable in warmer temperatures. In such climates, lightweight and breathable alternatives, like merino wool or synthetic materials, may be more appropriate. However, in moderate to cold climates, down is highly effective at providing insulation and keeping you warm.

5. How should down be cared for to maintain its warmth?

To maintain the warmth and longevity of down products, proper care is essential. It’s recommended to follow the care instructions provided by the manufacturer, but general guidelines include avoiding frequent washing, spot cleaning stains when possible, and using a front-loading washing machine with a gentle cycle for washing. Down should be dried thoroughly and fluffed after washing to restore its loft. Storing down items in a breathable bag and avoiding compression can also help maintain their insulation properties.

6. Are there any alternatives to down for insulation?

Yes, there are several alternatives to down for insulation. Synthetic materials, such as polyester or PrimaLoft, mimic the insulation properties of down while offering better moisture resistance. These synthetic insulators are often used in outdoor gear and provide warmth even when wet. Another alternative is natural wool, which has excellent insulating properties and can regulate body temperature. Additionally, some companies offer recycled down, which is made from reclaimed down products, providing a sustainable and eco-friendly alternative to traditional down insulation.

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