The measurement of the solar absorptance of the clothed human body – The case of Japanese, college-aged male subjects

In an outdoor environment, thermal comfort is affected by various factors, in particular solar radiation. Quantifying the solar absorptance of a human body is necessary for accurately assessing outdoor thermal comfort. Numerous studies have measured the solar absorptance of skin and fabrics. However, these measurements do not represent the solar absorptance of clothed humans. This study intends to determine the average solar absorptance of the human body wearing a combination of specific black and white garments and measure the average solar absorptance of Japanese, college-aged male subjects wearing casual summer, autumn, and winter clothing. The solar absorptance of the entire clothed human body was derived from these measurements. The solar absorptance of a black-shirt and black-trousers combination was found to be 0.76. For the combination of a white-shirt and white-trousers, the minimum solar absorptance was 0.38. Furthermore, the average solar absorptances of 30 Japanese, college-aged male subjects wearing casual clothing in summer, autumn, and winter were 0.66, 0.69, and 0.77, respectively. In summer, the average solar absorptance of the subjects in casual clothing depended on the color of tops. The average solar absorptances were suggested to be 0.76, 0.56, and 0.68 for subjects wearing black tops, white tops, and tops with Munsell values between 2 and 8, respectively.