A design method to realize thermal comfort in a room with floor heating was identified. The evaluation index used in the design method is the operative temperature which is an average of mean radiant temperature and air temperature. The mean radiant temperature was expressed by three variables; room air temperature, surface temperature of the floor heated, and shape factor viewing from a sitting person to the floor heated. The formula of the mean radiant temperature was conducted through experiments with floor heating using a cubic net radiometer. The value of shape factor in the design method was determined.
