A lack thereof is best. A vacum does not transfer heat.
Cotton And Wool
If the fabric color is dark then it absorb heat from the sun and the fabric's temperature will rise.
It is cooler on top of a mountain than it is below because the sun's rays do not heat the atmosphere directly. The sun's rays bump into dust particles, splitting into different directions. therefore, as the sun ray's reach the the crust, the soil on the ground insulates more heat as it is located near the timberline where the soil insulates more heat.
It insulates well for the same reason as double-pane glass: The air in the middle is a poor conductor of heat.
A lack thereof is best. A vacum does not transfer heat.
Wool is one of the best fabric for retaining heat.
Cotton And Wool
Wool is thick and insulates the heat so it won't escape.
Nylon
wool!
aluminum foil is going to be the worst insulater, paper is a good insulater but not the best, so the best is cotton.
The Adipose Connective Tissue insulates against heat loss and provides reserve fuel.
It insulates the window and keeps heat in.
Energy.
It insulates it, keeping the cool in and the heat out.
energy