Consider a jacket made up of six layers of 0.1 mm thick synthetic fabric (k = 0.15 W/m.K) with 1.2 mm thick air space (k = 0.026 W/m.K) between the fabric layers.
Assuming the inner surface temperature of the jacket to be 25 C and the surface area to be 1.25 m2, determine the heat loss through the jacket when the temperature of the outdoors is -5 C and the heat transfer co-efficient of outer surface is 25 W/m2.K.
What would be the thickness of a wool fabric (k = 0.04W/m.K) if the person has to achieve the same level of thermal comfort wearing a thick wool coat instead of a jacket.