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How Igloos Work

Properties of Igloos

When most people think about igloos, they picture a small, dome-shaped structure built entirely out of blocks of ice. They might imagine a small tunnel leading into the igloo. Actually, this image is surprisingly accurate.

building an igloo
Norbert Rosing/National Geographic/
Getty Images
An igloo builder wedges the last block into the top
of his abode.

We share a pretty similar perception of igloos in large part due to the many television shows and cartoons that have featured them over the years. The classic 1950s cartoon "Chilly Willy," about a wily and adventurous Alaskan penguin, prominently features his igloo. Overlooking the fact that penguins live neither in igloos nor in Alaska, the classic "Chilly Willy" igloo does resemble the most basic igloos inhabited by Inuit hunters.

However, igloos can vary widely from the popular image. In fact, an igloo can range from as small as a one-person hunting shelter to large, ceremonial structures joined to smaller igloos. The innovative architect can also create igloo villages by building attaching corridors and walls. This effectively turns a single-family dwelling into a multiroom compound capable of housing 20 people.

Smaller igloos are typically used by Inuit for fishing and hunting trips, as we've discussed. The larger, more permanent structures were created to form villages for longer-term, although still temporary, needs. Some of the largest villages boasted halls for special occasions such as dances and feasts. Most igloos are self-sustaining due to the strength of ice. But when spring hits, the sun and warmer temperatures turn igloos to slush. It's best to steer clear of defrosting igloos to avoid being caught in a cave-in.

Snow: the Miracle Insulator
Snow is a relatively easy material to work with for the experienced igloo-maker. It is packed tightly by the freezing winds common to the areas inhabited by Inuit. Snow is easy to cut and surprisingly sturdy, and snow blocks are also pretty lightweight. Still, snow is pretty cold, so many people are skeptical of the igloo's ability to keep its occupants from freezing to death. The truth is, inhabitants might not be able to lounge around in their underwear, but they can exist comfortably inside an igloo, and a subzero sleeping bag can take the edge off.

The igloo has stood the test of time as a living establishment. Some experts say that a well-constructed igloo, coupled with a very small oil lamp and plain old body heat, can warm an igloo up to 40 degrees above the outside temperature. Hypothetically, if it is -40°C outside, the igloo has the potential to warm up to 0°C. It accomplishes this amazing feat thanks to several features:

  • The walls block the wind, which is often so bitter that it can make freezing temperatures feel many degrees colder.
  • Snow and ice work as insulators to trap body heat inside the igloo. Thus, the occupants of an igloo double as a furnace of sorts.
  • Insulation capabilities actually increase a few days after construction. Body heat and sun exposure cause the inside of the igloo to melt ever so slightly. When the igloo is unoccupied during hunting expeditions, the melted snow freezes over, turning into ice. Several days of gradual thawing and refreezing turns the entire structure to solid ice, making it not only superstrong, but also warmer than ever.
hard-packed snow
Kenneth Garrett/National Geographic/Getty Images
A good igloo requires plenty of hard-packed snow. This fresh blanketing of snow is ideal for igloo construction,
no reindeer required.

It should be noted that the right type of snow is necessary to build an igloo. The soft, powdery stuff that falls in most backyards is not hard or packed tightly enough to build a reliable igloo. But if you're lucky enough to find the right kind of snow, you can try your hand at making your own igloo. Learn how on the next page.