Chapter 1, Problem 1.29P

Under conditions for which the same room temperatureis maintained by a heating or cooling system, it is not uncommonfor a person to feel chilled in the winter but comfortable in the summer. Provide a plausible explanation for this situation (with supporting calculations)by considering a room whose air temperature is maintained at 20°C throughout the year, while the walls ofthe room are nominally at 27°C and 14°C in the summer and winter, respectively. The exposed surface of aperson in the room may be assumed to be at a temperature of 32°C throughout the year and to have an emissivity of 0.90. The coefficient associated with heattransfer by natural convection between the person andthe room air is approximately $2{\text{W/m}}^{\text{2}}\cdot \text{K}$ .