In other eras and parts of the world, people have kept warm without recourse to the thermostat dial. Here’s one way to make warm shelter without electricity or any conventional materials. Today let’s admire the clever engineering of the traditional igloo.
A SHELTER FROM THE COLD, MADE OF SNOW?
While warmth and shelter is probably not anyone’s first association with the word “snow” (except in the getting-tucked-away-inside sense), this ancient building technique can make a space much more pleasant to hang out in than an open snow field in a storm. The igloo was an innovation like many other’s in human history – it dealt with the specific conditions of place by using what was available. In the case of the Arctic peoples, their condition was cold and dark and their most generally available material was snow.
HOW IT WORKS – STRUCTURALLY
The structural principle of the igloo is the same as any dome or arch. Gravity pulls all objects toward each other – effectively, toward the center of the earth, or down. Each block in an igloo’s curve is pulled straight down but prevented from falling by the blocks around it. The center block (keystone) can’t fall because its top is wider than its base, so instead it rests on the blocks all around it. Forces are transferred from one to the next until they reach the ground. That transfer also caused them to want to push outward so careful attention must be paid to the base or it will simply slide outward and collapse the dome. In gothic cathedrals, this is accomplished with flying buttresses. In igloos … they use more snow.
HOW IT WORKS – THERMALLY
Like the structure, igloos preserve warmth effectively using a very simple principle. Heat rises. Because the entrance to the igloo is below the main level, heat doesn’t travel out that opening but is trapped inside the dome and accumulates as the person or people inside radiate it. Supplemental heat can be provided by a candle. Its important to have a vent though – and to go easy on the burning, even of candles – because in the enclosed space its possible to use up too much oxygen.
It never becomes toasty warm but it sure beats going outside. As the inside of the igloo warms the inner layer melts and then re-freezes making it an even better air tight space. By raising the sleeping areas up off the floor, people inside can get close the warmest air. They also bundle up even inside and use insulating layers to keep themselves separated from the cold ground.
SO WHAT CAN WE LEARN?
Most of us wouldn’t feel very happy about a shelter that used “warmer than freezing” as its criteria for comfort. However, there’s a lot we can take away from the igloo from a sustainability perspective.
- A little heat goes a long way in a small area. Especially if that area is well insulated.
- Keeping ceilings low means heat won’t rise up past the area people spend time in.
- And staying bundled up in the winter, even inside, uses a lot less energy.
Few structures use less in the way of materials and energy. What can we do with that challenge?