Saving On The Heating Bill

The easiest way to reduce the amount of energy needed to heat a house is with good insulation. Arctic animals try to keep their temperature constant too, but their legs remain cold, while their head and body core remain warm. This seems like a difficult feat, but with an adaptation called countercurrent heat exchange it requires little energy. In this system of circulation arteries, which carry warm blood from the heart to the extremities, lie very close to the veins, which carry blood from the cold extremities of the body back to the heart. In this way, heat from the warm arterial blood is transferred to the colder blood in a vein, thereby cooling the blood in the artery and warming the venous blood. Thus, as blood from the body reaches the extremities, it is already cooled and loses very little additional heat to the environment.

Conversely, cool blood from the extremities is warmed prior to reaching the body core and does not shock the heart or reduce internal body temperature. The countercurrent exchange system has been well studied in both the arctic fox and the caribou, which maintain their core temperature nearly 30°C higher than their appendages!