Reducing large electricity consumption is a primary concern for researchers and practitioners in smart buildings. Peak electricity demand is the result of temporarily correlated energy demand surges caused by uncoordinated operation of subsystems such as air-conditioning, heating, ventilating and so on. It might cause severe issues such as service disruption and high cost of energy production and distribution. Many buildings applied various energy saving policies with building automation system to control the behaviors of smart devices to save energy. In this paper, we propose a framework for peak electricity demand control based on constraint programing technology in smart building.