Due to liberalization processes initiated on Japan's power market since 2000, a significant higher congestion on the power grid is expected entailing a higher vulnerability to shortages. With increasing aspirations on power supply security, an interaction with the demand side has become inevitable to reduce the congestion without the need for new generation or transmission capacities. Attaining efficiency close to the optimum in curtailing and rescheduling loads, the fast automatic processing of essential information affecting the performance of the power grid is crucial. This approach shows a solution for hybrid demand control integrating a vast number of small and medium sized enterprises for centralized load management based on locally collected environmental data. The hardware and software of this system has been prototyped and evaluated. Evaluation tests show the capability of this system to deliver the necessary infrastructure necessary for demand control.