How Do Igloos Keep Warm Inside

Igloos are really interesting and fascinating structures. It leaves us wondering and asking certain questions like ” how do igloos keep warm inside?”

Igloos are originally know as houses made of snow. In recent times, other materials like glass have been used its construction.  They are found in extremely cold regions of the world, where wood is scarce. Igloos though made of snow, are surprisingly warm inside. The interior temperature of igloos can be as much as forty degrees higher than the external temperature. The secret of the igloo’s warmth lies in its sole building material; snow.

Igloos are built from snow, but not just any snow. They are built from compressed snow. Snow is semi-frozen water, and unlike ice, it has surprisingly insulating properties, making it an ideal building material especially in places where wood is scarce. Snow is composed of a high percentage of air, trapped in tiny crystals. Since there is little space for the movement of the air in these crystals, heat circulation with its surrounding is greatly reduced. Hence, it can trap heat but can release very little to the environment.

Also, igloos are built in a way that the interior is bigger than the exterior. They are built by digging a hole that is beneath the snowy landscape. It’s almost like an underground home. A good portion of the living space of the igloo is underground, and hence, sheltered from fierce cold winds and drafts that might flow in through the doorway of the igloo.

The Internal Structure 

The internal structure of igloos also helps them keep warm. The interior of igloos consists of three levels; the upper, the middle, and the lower levels. The lower levels are the coldest parts of igloos. This is because cold air is denser than warm air, and hence, settles at the bottom of the igloo.

The middle and upper levels aren’t as cold as the lower level. They consist mostly of warm air displaced by the cold air. Hence, these two levels are warmer than the cold level. Due to this fact, the upper level of the igloo is where people sleep. It is warmer, and hence considerably ideal for sleeping.

The middle layer is the layer where most activities are carried out. The lower layer serves as a “cold dump.” The cold air settles in this layer and leaves through the very low opening that serves as an entrance into the igloo. Of course, it would seem that cold air could also enter into igloos through this opening.

However, because the doorways of these igloos are at right angles, the cold winds can’t blow directly into them through these low openings, hence, minimizing the amount of cold air that enters these igloos. To further minimize cold air from flowing through these doorways, a curtain made from animal skin — perhaps seal or whale skin — is hung on the doorway, to serve as a windbreak.

The beds of igloos are usually raised platforms made of compressed snow. These platforms are covered with branches, seal skins, blankets, and other thick clothing to make them warm and cozy. In as much as the snow is an insulator, a bed made entirely of snow isn’t adequately warm. Remember, snow being an insulator doesn’t reduce its temperature of below zero degrees. It’s just like sleeping on a very cold insulator. It won’t lose heat that easily, but it will still be cold without blankets and other thick coverings.

Classification Of Igloos

Traditionally, igloos are classified based on their size. The smallest igloos are constructed as temporary shelters and are usually the warmest. This is because the heat circulates over a small area. Intermediate-sized igloos are constructed for family dwelling. It can house as much as seven people.


The largest igloos are usually constructed for festivals and special occasions. The area inside the igloos increases from the small-sized igloos to the large-sized igloos. Hence, the area for heat circulation increases. So by convention, small-sized igloos are considerably warmer than large-sized igloos.

Ways To Increase The Warmth Of An Igloo

Fires can be lit in igloos. This might sound absurd especially since igloos are made of snow. However, these fires are lit at the centers of igloos, at the middle level. Since the fire is at the center, it is farthest away from all walls of the igloo. This minimizes the possibility of the igloo melting.

Also, part of the heat generated by the fire is also lost to the colder air outside the igloo, albeit in little amounts. Hence, there’s no fear of the igloo melting.

Apart from fires, oil lamps can also be lit in igloos. These oil lamps, are known as “qulliqs.” Qulliqs [1] are fueled by a seal or whale blubber. This makes them an ideal source of heat, especially in places where wood for fires is scarce.
Another source of warmth in igloos is body heat. Our bodies emit heat. This contributes to the warmth of igloos.

Small-sized igloos, though warmer than large-sized igloos, can house only two people at most. However, large-sized igloos can house as much as ten people. The heat emitted from people living in large-sized igloos is considerably greater than the heat emitted from people living in small-sized igloos. This contributes greatly to the heat generated in large-sized igloos.

With all these sources of heat, it might seem unrealistic that igloos don’t melt from the heat exposure. Well, they do melt. After some days, body heat, sun exposure, as well as other heat sources cause the inside of igloos to melt. With time, when these igloos are unoccupied, or when the sources of heat are removed, the melted snow freezes over, turning to ice.

This process might take several days, but it is worth the wait. With time, the entire igloo becomes reinforced, making it stronger and warmer. An adult can stand on top of such an igloo, without causing it to collapse.
Igloos are made from compressed snow for a reason. Igloos built from any other type of snow wouldn’t last long. Also, because they are made from compressed snow, igloos can withstand fierce cold winds. They serve as efficient windbreaks.


  1. Fact Sheet [Link]