Question

Why does compressing lofted insulation, like down or synthetic fibers, significantly reduce its ability to keep you warm?

Accepted Answer

Lofted insulation works by trapping a layer of still, dry air between your body and the outside environment. Air is a poor conductor of heat, meaning it does not easily transfer energy from a warm object to a cold one, which is why trapping it is the primary way to prevent heat loss. Down feathers or synthetic fibers function as a scaffold to hold this air in place within the spaces between the filaments. When you compress this material, you physically collapse the empty spaces where the air resides, forcing the air out of the insulation. With the air removed or significantly reduced, the insulating layer becomes thinner and more dense. Dense materials are much better conductors of heat than air, so the insulation is no longer able to create a barrier that prevents your body heat from escaping. For example, a thick, puffy down jacket is warm because it holds a large volume of air, but if you squeeze it down to a thin layer, you have essentially removed the insulating barrier, allowing heat to flow directly through the material to the outside air.

Home → All Courses → Health and Medicine Courses → Staying Warm in Cold Places → Flashcard

Why does compressing lofted insulation, like down or synthetic fibers, significantly reduce its ability to keep you warm?