An air conditioner comprising: an air conditioner main unit including an outdoor unit and at least one indoor unit connected to the outdoor unit; and a remote controller for remotely controlling the air conditioner main unit, wherein the at least one indoor unit includes a representative indoor unit, characterised in that the outdoor unit is configured to detect an average bus voltage and a corrected average primary current for each sample period and to calculate a power consumption from the detected average bus voltage and corrected average primary current, wherein the at least one indoor unit is configured to calculate a power consumption when a change has arisen in a number of rotations of a fan of said at least one indoor unit, and to transmit the calculated power consumption to the outdoor unit every time a change has arisen in the calculated power consumption, wherein the outdoor unit is configured to totalize the power consumption calculated by the outdoor unit and the power consumption transmitted from the indoor unit, thereby obtaining a total power consumption (Pt), and to transmit the total power consumption (Pt) to the representative indoor unit at each communication which is performed periodically, wherein the representative indoor unit is configured to integrate the total power consumption (Pt) and to calculate an amount of power consumption, and to transmit the amount of power consumption to the remote controller, and wherein the remote controller is configured to convert the amount of power consumption into an amount of CO 2 emission, and to display the amount of CO 2 emission. an air conditioner main unit including an outdoor unit and at least one indoor unit connected to the outdoor unit; and a remote controller for remotely controlling the air conditioner main unit, wherein the at least one indoor unit includes a representative indoor unit, characterised in that the outdoor unit is configured to detect an average bus voltage and a corrected average primary current for each sample period and to calculate a power consumption from the detected average bus voltage and corrected average primary current, wherein the at least one indoor unit is configured to calculate a power consumption when a change has arisen in a number of rotations of a fan of said at least one indoor unit, and to transmit the calculated power consumption to the outdoor unit every time a change has arisen in the calculated power consumption, wherein the outdoor unit is configured to totalize the power consumption calculated by the outdoor unit and the power consumption transmitted from the indoor unit, thereby obtaining a total power consumption (Pt), and to transmit the total power consumption (Pt) to the representative indoor unit at each communication which is performed periodically, wherein the representative indoor unit is configured to integrate the total power consumption (Pt) and to calculate an amount of power consumption, and to transmit the amount of power consumption to the remote controller, and wherein the remote controller is configured to convert the amount of power consumption into an amount of CO 2 emission, and to display the amount of CO 2 emission.