A person feels very comfortable in his house in light clothi

A person feels very comfortable in his house in light clothing when the thermostat is set at 22 degree C and the MRT = 22 degree C. During a cold day, the MRT drops to 18 degree C. To what value must the indoor dry-bulb air temperature be raised to maintain the same level of comfort? If the person sits near a window and receives solar radiation, the thermostat can be lowered. What types of factors will influence the amount by which the thermostat can be lowered?

Solution

skin has two predominent modes are convection and radiation. Convection heat trasnfer rate on your skin at the air 18C is q(c)= hA(Ts-T), where h is the convection coefficient, A is the surface area, Ts is the temperature of the surface of your skin (or the temperature percieved by you) and T is the temperature of the air.

Inside and outside this value is the same, what makes the difference is the radiation value that is detemined by

q(r)=ESA((Ts)⁴ - (T*)⁴ )

where E is the emissivity of your skin, S is the Boltzmann constant, A is the surface area, Ts is the surface temp, and T* is the temperature of surrounding surfaces.