Metabolic heat production
An estimate of metabolic heat production in the body is fundamental to the assessment of human thermal environments. If no heat were produced, as in death, the body would achieve thermal equilibrium with surrounding conditions. Heat is produced in the cells of the living body and most of the investigation into human response to thermal environments can be regarded as the study of the distribution and dispersion of this heat. It is often considered that heat is a by-product from cells; however this is misleading, especially in homeotherms where the heat production is an important integral part of the living system.