Igloos stay warm inside thanks to the occupants' body heat, which warms up the enclosed space by slightly melting the snow, which then refreezes to form an insulating layer and prevent heat from escaping.
Snow contains a lot of trapped air between its flakes. It is precisely these tiny pockets of still air that make snow an excellent thermal insulator: still air conducts heat very poorly. As a result, heat inside the igloo escapes very slowly, even if it is very cold outside. The more uniformly packed the snow used to build the igloo is, the more effective the insulating layer is. Fresh, powdery snow is often less effective than compacted snow because it allows cold and wind to pass through too easily.
This rounded shape facilitates the circulation of warm air inside the igloo. The warm air, being lighter, naturally rises to the top of the dome and descends as it cools against the walls, creating a constant air movement. This convection allows for even heat distribution. Additionally, the dome structure efficiently distributes the weight of the snow throughout the entire construction, thereby enhancing its strength and resistance to loads. This particular shape also minimizes the surface exposed to the cold outside wind, significantly reducing heat loss.
In an igloo, just the body heat is enough to make the interior comfortable. The inhabitants constantly emit heat, like little natural radiators at around 37°C. This heat stays inside thanks to the insulating properties of the snow and the dome shape. As a result, even when it’s freezing outside, it can easily rise a few degrees above zero inside. The more people there are inside, the more we naturally warm the space without extra effort. There’s no need for fire or heating; just a few people are enough to create a soft and stable atmosphere. It’s simply our bodies, which continuously produce thermal energy, that gently transform the igloo into a warm space—the secret lies in effectively retaining that heat.
The dome shape of the igloo is ideal for deflecting gusts of wind from the outside. Since there are no right angles or vertical surfaces, the wind glides all around without being able to penetrate or cool the interior. The piled snow acts as a natural shield, preventing heat loss due to drafts. Without the infiltration of cold from the outside, the temperature remains pleasant and comfortable inside. Thanks to this rounded profile, even in the middle of a storm, the air inside stays surprisingly calm.
Snow has a clever advantage: it absorbs and slowly releases humidity from the air. As a result, the inside of the igloo remains relatively dry, without too much of a damp or muggy feeling. When warm, humid air rises toward the cooler ceiling, water gently forms a thin layer of condensation that freezes quickly. This impermeable frost prevents additional moisture from penetrating too deeply into the walls, preserving the insulating properties of the igloo while keeping the indoor air pleasant to breathe.
In the Inuit language, 'igloo' simply means 'house': this term refers not only to snow shelters but to all types of dwellings, including those made of wood or stone.
Unlike popular belief, igloos are not meant to be permanent — they are typically used as temporary shelters during winter expeditions or during the seasonal migrations of northern populations.
Traditional igloos often have a lowered entrance so that the lighter, warm air remains trapped higher inside, while the heavier, cold air stays lower and outside.
Due to the excellent insulation provided by the compacted snow, a simple candle is often enough to significantly raise the temperature inside an igloo.
Usually, building a traditional igloo takes between 2 and 6 hours, depending on the size and the skill of the people doing the construction.
The dome shape of an igloo allows for an even and efficient distribution of heat. Additionally, it reduces the surface area exposed to the cold outside, thereby helping to retain more heat inside.
The snow melts slightly right after the construction, then quickly freezes again due to temperature fluctuations. This reinforces the interior walls and makes the structure even more insulated.
Yes, thanks to their aerodynamic shape, igloos withstand heavy snowstorms particularly well, effectively protecting their occupants from strong winds and significant precipitation.
The interior temperature of an igloo can generally remain around 0°C to 15°C, which is relatively warm compared to the extreme outside temperatures that can drop to -40°C or lower.
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