This study is to suggest an RTP based dimming control system designed to address visual unpleasantness among occupants due to drastic change of illuminance and to optimize power consumption and expenses. The suggested system adjusts the lighting output in the current space according to the target illuminance and the daylight quantity in that space. If the change of illuminance exceeds 20% of the previous illuminance, the control time interval and number of controls are adjusted through the polling period control algorithm so that the occupant cannot recognize the visual unpleasantness due to change of illuminance. In addition, the system classifies charges into three steps depending on the power load in reference to the RTP. The maximum target illuminance of office space is 600 lx, the average 400 lx, and the min. 300 lx respectively..To evaluate the performance of the suggested system, two systems were applied to two comparison groups comparison group A and comparison group B to which the polling period control algorithm was not applied: comparison group A was set to maintain the fixed target illuminance regardless of changes in electric charges while comparison group B was designed to change the target illuminance depending on the RTP. (C) 2016 Elsevier B.V. All rights reserved.