This study focuses on a south-facing room in an office building at a university in Qingdao, where a floor radiant air-conditioning system is employed. The thermal environment of the interior and perimeter zones, as well as the system’s energy consumption, are investigated. A simulation model of the room and its HVAC system was developed using TRNSYS software, and the model’s accuracy was validated using measured data. Based on the differences between air temperature and operative temperature within the room, the space was divided into interior and perimeter zones. Different control strategies using air temperature and operative temperature as control signals were proposed accordingly. After verifying the model’s accuracy, TRNSYS was used to simulate various control modes, analyzing thermal comfort and energy consumption in each zone. A comparison of indoor comfort and energy use under each control strategy was conducted to identify the control mode that minimizes energy consumption while meeting basic thermal comfort requirements.