In recent years, energy saving has progressed in the construction field, and passive design methods that make effective use of natural energy are often used. One of these methods is direct gain, which suppresses temperature changes between day and night, achieving both comfort and energy saving. In this study, we use unsteady CFD analysis to understand the heat storage characteristics and to study the effects of radiation and convection heat from the storage material when solar radiation is incident in a room with storage material on the floor. In this report, we classify the material structure of the floor into three types and compare them.
