Effects of an indoor thermal environment created by heating systems in Japan based on skin moisture content and thermal comfort

Recently, there has been increasing concern about dry skin in Japan with regards to beauty and atopic dermatitis. People are likely to feel dry more frequently in a heated room in winter. The purpose of this study was to determine the effects of a thermal environment created by heating systems on skin moisture content and thermal comfort and to propose an effective method to maintain skin moisture content when using heating systems. In this study, subjective tests were conducted in model living rooms in a climate chamber. The tests were conducted in a total of 18 different thermal conditions. Air temperatures were controlled using a floor heating system or an air conditioner, and relative humidity conditions were set using a humidifier. During the tests, the subjects answered questionnaires regarding thermal comfort. The results suggest that the air velocity in an air-conditioned room increases with increasing air temperature, resulting in dry skin on the face. Therefore, it is reasonable to suppose that avoiding direct exposure to airflow is effective for increasing skin moisture content. The results also suggest that skin moisture content is influenced by relative humidity, absolute humidity, and air temperature.