This paper describes the results of entropy analysis in human body and built thermal environment. Followings are found. In case of heat stroke onset, accumulated entropy generation of human core is 69% in comparison with in case of air conditioning. This shows another significance being different from core temperature 38℃ and more in a definition of heatstroke. Entropy disposal is essential to ensure adequate entropy generation for all the working subsystems. On the other hand, if subsystems are regarded as a system forming multiple-layer structure, excessive entropy disposal from even one subsystem causes hindrances the whole system’s sustainable activity.
