Thermal comfort is the priority factor influencing indoor environments, with impact on the health and productivity of the inhabitants, and plays a pivotal role in energy saving. Many studies on performance of building envelops focused on its influence on building energy consumption, and ignored its impact on occupants’ thermal comfort. While it is already a common practice to save energy consumption by adjusting the settings of indoor temperatures, thus this study performed a holistic experiment and analysis by taking into account the human requirements on thermal comfort, performances of building envelops, and energy consumption of air-conditioning system. The experiments are conducted in two rooms with about same size but different envelop performances. There are two kinds of experiments: (1) Both room were conditioned at 25°C to demonstrate the impacts of envelop performance on indoor thermal comfort and building energy consumption; (2) Both rooms were conditioned at PPD=20% to demonstrate the impacts of envelop performance on the potential of energy savings by setting-up the indoor temperature but without scarifying occupants’ thermal comfort. The results show that measuring envelop performance of a building from the perspective of thermal comfort, will equip the users of well designed building the ability to creates further energy savings by reasonable adjustments of indoor temperatures.