A method of controlling an electric product included in network system, the method comprising: performing a communication between a power supply source and the electric product in a home network; recognizing (S120, S220) an on-peak time period in which energy information including at least electricity cost information is over a set value; and limiting a function of a part of power consumption units (81, 82, 83) constituting the electric product when at least one period of a driving time of the electric product is disposed within the on-peak time period, characterized in that the power consumption units (81, 82, 83) comprise a motor, a heater and fan, wherein limiting of the function of the part of the power consumption units (81, 82, 83) comprises at least one of: limiting the function of the power consumption unit (81, 82, 83) having higher power consumption than the others, among the motor, the heater and the fan; limiting the function of the power consumption unit (81, 82, 83) having a power consumption amount greater than a preset reference amount, among the motor, the heater and the fan; and limiting the function of the power consumption unit (81, 82, 83) having a largest power consumption amount, among the motor, the heater and the fan; wherein the limiting the function comprises stopping the functions of the power consumption units (81, 82, 83) or decreasing an output of the power consumption unit (81, 82, 83) to a set output or less, wherein the electric product comprises a refrigerator including: a storage part; a cool air supply part comprising a compressor, a condenser, an expander and an evaporator to supply cool air to the storage part; a cool air storage part selectively communicating with the storage part and comprising a cool air storage agent that is frozen by cool air and an insulation material that thermally insulates the cool air storage agent from the storage space, and wherein the limiting of the function of the part of the power consumption units (81, 82, 83) comprises controlling the compressor to have a lower output than a predetermined output thereof and supplying stored cool air in the cool air storage part to the storage part to maintain performance of the refrigerator. performing a communication between a power supply source and the electric product in a home network; recognizing (S120, S220) an on-peak time period in which energy information including at least electricity cost information is over a set value; and limiting a function of a part of power consumption units (81, 82, 83) constituting the electric product when at least one period of a driving time of the electric product is disposed within the on-peak time period, characterized in that the power consumption units (81, 82, 83) comprise a motor, a heater and fan, limiting the function of the power consumption unit (81, 82, 83) having higher power consumption than the others, among the motor, the heater and the fan; limiting the function of the power consumption unit (81, 82, 83) having a power consumption amount greater than a preset reference amount, among the motor, the heater and the fan; and limiting the function of the power consumption unit (81, 82, 83) having a largest power consumption amount, among the motor, the heater and the fan; wherein the limiting the function comprises stopping the functions of the power consumption units (81, 82, 83) or decreasing an output of the power consumption unit (81, 82, 83) to a set output or less, wherein the electric product comprises a refrigerator including: a storage part; a cool air supply part comprising a compressor, a condenser, an expander and an evaporator to supply cool air to the storage part; a cool air storage part selectively communicating with the storage part and comprising a cool air storage agent that is frozen by cool air and an insulation material that thermally insulates the cool air storage agent from the storage space, and a storage part; a cool air supply part comprising a compressor, a condenser, an expander and an evaporator to supply cool air to the storage part; a cool air storage part selectively communicating with the storage part and comprising a cool air storage agent that is frozen by cool air and an insulation material that thermally insulates the cool air storage agent from the storage space, and wherein the limiting of the function of the part of the power consumption units (81, 82, 83) comprises controlling the compressor to have a lower output than a predetermined output thereof and supplying stored cool air in the cool air storage part to the storage part to maintain performance of the refrigerator.