There are many moisture-related problems and topics in the field of buildings. In this review, the past research trend in the field of moisture in Japan is first overviewed by examining the activities reported in the AIJ symposium on thermal environment. The theme of the symposium held every 10 years indicates the research trend, i.e., the research until the year 1990 established the theoretical basis of heat and moisture transfer; then, until the year 2000, the established theory was developed to be applied in practice, and until the year 2010 the results obtained so far were presented to a wide range of occupants and end users.

The indoor humidity and the accompanying problems are closely related to the fact that most of the materials constituting the building are porous, and thus absorb water vapor. Therefore, the important topics of moisture research emphasizing the heat and moisture transfer in porous building materials are described, i.e., heat and moisture transfer in porous material and method of analysis, condensation and mitigation of humidity change, freezing-thawing, mold and wood-rotting fungi, health and comfort, conservation of cultural properties, etc.

Finally, the challenges and prospects are presented.

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.