Since your brain needs oxygen to function, your body can't cut off the flow of blood to your head in order to conserve heat. Consequently, much of your body head can be lost through an uncovered head and neck. A major source of heat loss. Heat is lost directly from exposed skin and the head. Handling gasoline, and other super-cooled liquids, at low temperatures is especially dangerous.
Heat is lost from the wind carrying away heat from the surface of the skin.
This includes wind-chill effects. Loss from evaporation of sweat, moisture from the skin and lungs produces substantial heat loss. This is little that can be done about this. We need to allow for this by using breathable fabrics to allow this moisture to pass out freely. Heat lost from inhaling cold air and exhaling warm air.