The construction principle of an igloo is simple: you just need a lot of snow, a spade and a saw. In an emergency, a board or ski is sufficient. However, caution is advised. There are two types of treacherous design flaws: the igloo can bury the occupants under itself or it can be so tight that not enough oxygen gets inside to breathe. This is why you should definitely have an expert with you when you build your own igloo for the first time.
The principle is simple, but implementation requires skill: igloo building.
In principle, an igloo construction works like this: You look for snow that is as compact as possible and cut blocks of around half a meter edge length from it. From this you form a circle with a circumference of two to three meters. The blocks are layered on top of one another in a spiral, shifting them conically towards the center until a dome is created. Don't forget the opening for the entrance. Later, more blocks are placed in front of the entrance to keep the wind out.
Inserting the keystone, the last block at the top of the igloo ceiling, is critical. It takes some skill to tailor it to exactly fill the last gap. Some of the remaining holes between the blocks of the igloo can still be filled with snow - but not all of them, otherwise the oxygen supply in the igloo is endangered.
Why is it warm in the igloo?
Snow traps between 90 and 25 percent of air, depending on how old and compact it is. Air is an excellent insulation material when it cannot circulate. Styrofoam works on the same principle: A lot of air is enclosed in less solid matter. That makes the whole thing relatively light and well insulating.
It gets comfortably warm in the igloo. © Mauritius
The wall of the igloo serves as a very good insulator against the very cold environment and the wind. The air in the igloo is warmed by the body heat of the occupants and the warm air rises upwards. There she cannot escape - provided the entrance to the igloo is low enough. The cozy warm air stays inside, the cold air from outside cannot get in. And hardly anything is lost to the outside through heat conduction, because snow is a good insulator.
Over time, the inner wall of the igloo becomes icy. Here the snow thaws and partially freezes again. This process impairs the stability, and in the long term the insulating effect would also deteriorate, since ice hardly encloses any air and it is therefore insulated much worse. That is why the shelf life of an igloo is limited. Depending on the building skills, solar radiation and outside temperature, a new igloo must be built after a few days or a few weeks.