A demand response (DR) system, computer-readable medium and method are disclosed. The DR system controls a high-power-consumption load to be pre-operated or post-operated in a low-power-rate interval instead of a high-power-rate interval, and reduces an amount of power consumption required for a high-power-rate interval, resulting in reduction of power rates. In addition, limitation to household appliance operation is minimized, to greatly reduce inconvenience of a user.