Question

How much power, in watts, does a human being consume? We can calculate a very rough estimate if we assume that all of the energy needed to power a human body ultimately turns into heat that is lost by radiative cooling. Let's assume that we're talking about a person with a body temperature of 37°C, sitting in a room that is at 25°C. We'll also assume that the human and their surroundings are perfect blackbodies (i.e. objects that have a perfect ability to exchange heat by emitting and absorbing electromagnetic radiation.)

If the person has a surface area of 1.8 square meters, what is the rate, in watts, of their net heat loss to the environment? The Stefan-Boltzmann constant is 5.7 x 10^-8 W/(m²K⁴).

Answer 1