In an office space, each office worker has his or her own preference for thermal environmental conditions and personal thermal comfort. Recently, as a solution to such problems, personal air-conditioning systems have attracted much attention to improve the thermal comfort of office workers. Using a personal air-conditioning system, each worker can adjust the thermal environment to his or her desired preference. To create a personal air-conditioning system, the authors enhance an office chair using an airflow generator that has an environment adjustment function. This chair, called a “cool chair,” has been under development since 2003. In this study, the authors develop a new model called cool chair 2016 where thermal environmental selection range is improved. In a physical performance test using a thermal manikin, the equivalent temperature of the entire body was noticeably lower than that of a user seated in a normal office chair. Moreover, the results of a trial test by workers in an office show that workers who used the cool chair felt more comfortable.