Measurement Method for the Solar Absorptance of a Standing Clothed Human Body

Abstract

Solar radiation is one of the most important components of the human–energy balance outdoors. To assess outdoor thermal comfort accurately, quantification of the solar absorptance of a clothed human body is needed. A measurement method using subjects lying on a horizontal roof surface was proposed in a previous study. However, this method only provided solar absorptance for the front side of the human body. Therefore, this study aims to establish a method of measurement of the solar absorptance of a standing clothed subject to determine the solar absorptance in any direction. Measurements were performed in September 2012 at Daido University in Nagoya, Japan. Four male and four female Japanese college-aged subjects participated in the experiments. Four clothing ensembles of a black shirt and black trousers (B-B), a black shirt and white trousers (B-W), a white shirt and black trousers (W-B), and a white shirt and white trousers (W-W) were tested for male subjects. Two clothing conditions of a black one-piece dress (Black) and a white one (White) were tested for female subjects. All subjects participated in an additional condition with their casual clothing ensembles. The following findings were obtained through the measurements. For the male subjects, the solar absorptance of the black shirt and black trousers ensemble (B-B) had the maximum value of 0.77. Meanwhile, the white shirt and white trousers ensemble (W-W) provided the minimum solar absorptance of 0.48. For the female subjects, the solar absorptances of the black and white one-piece dresses were 0.74 and 0.44, respectively. The solar absorptances of casual clothing were 0.61 and 0.59 for male and female subjects, respectively. The measurement method using the standing subject used in this study was appropriate for determining the solar absorptances of the clothed human body. Furthermore, this method was able to quantify the solar absorptance in several directions as well as for the front side of the subject.