The effect of solar radiation on temperature distribution in outdoor human–clothing–environment systems

• Effects of solar radiation on clothing were simulated and studied experimentally.
• Solar radiation was modeled as heat source in heat conduction equation.
• Temperature formations differ depending on solar radiation.
• Absorptance can sufficiently determine temperature distributions in clothing.

The present study investigates heat transfer in the human–clothing–environment system under solar radiation. A new thermal model integrating the solar radiation absorption by clothing, as well as heat conduction within the air layer and heat convection on the clothing surface, is presented. The heat transfer in this system is simply explained based on the heat conduction equation; heat transfer relating to solar radiation is added as the source of heat generation at the surface of clothing. The temperature distributions inside clothing are well predicted with variations in the amount of solar radiation, ambient temperature, air gap depth, and radiative properties. Temperatures are increased or decreased linearly with changes in the air gap distance, confirming that the temperature of the air layer inside clothing is governed by conduction. Temperature distributions differ depending on solar radiation and also radiative properties, particularly absorptance, indicating that radiative heat transfer must be included to evaluate clothing heat transfer.