Tuesday, March 4, 2014
Shelter vs. Insulation
Since your clothing is your primary shelter when you're outdoors, and it's your first line of defense against the elements, let’s take a look at the difference between shelter and insulation when it applies to what you’re wearing.
There is a subtle difference between shelter and insulation, and when you're concerned with keeping yourself protected from cold weather, that difference is very important.
The purpose of insulation is to eliminate the negative effects of the climate insofar as heat and cold are concerned. Insulation might provide some shelter. But a material that provides only shelter is not necessarily good insulation. That might sound confusing, so let me explain.
A sheet of plastic might shelter you from the rain or turn the wind, but it won't do much to keep heat and cold from transferring. On the other hand, if your shelter and insulation strategies are good, you will be protected from the rain or wind, and thermal transfer will be cut to a minimum.
Generally speaking, several materials are used in combination with each other to achieve a good shelter and insulation factors. Some materials offer certain characteristics that are missing in others, so you need to think in terms of what quality can be derived from the materials at hand, and how they can be used to compliment each other.
Think about your house — the roof shingles do the job of providing shelter from the rain, and a different material (like spun fiberglass that looks like cotton candy) does the job of insulation. Together, they do the job of keeping the inside of the house safe and comfortable
Well, the same concept applies to your clothing. Think of your clothing as a walk-around shelter system that consists of a variety of elements that work together to keep you safe. You want material that will keep the moisture (like rain and snow) out, yet will at the same time allow moisture from inside (like perspiration) to escape. You want a material that will turn the wind away, and will radiate your body heat back at you. And, you need insulation to hold your body warmth close to you and prevent outside cold from penetrating.
Take a look at the photo above. Dressing in layers is the best method to get the benefits of both shelter and insulation. The outer layer protects agains moisture and wind coming through from outside, but allows condensation to move out into the atmosphere. Inner layers, if they're made of the right materials, trap body warmth, but don't soak up and hold moisture.
Having the ability to open the layers to allow ventilation is important, especially when you're working hard in a survival situation.
If you can arrange for that combination of qualities in your clothing, you will be dressed for survival.