Controller and control method

A controller configured to control an air conditioner, the controller comprising:

• a communication unit configured to communicate with the air conditioner;
• and
• a control unit configured to control the air conditioner via the communication unit, wherein
• the control unit has an activation mode in which the air conditioner is activated before a set time so as to cause a temperature of an indoor space to reach a set temperature at the set time,
• in the activation mode, for each of a plurality of performance suppression rates, the control unit calculates a power consumption amount of the air conditioner required from the activation of the air conditioner until the temperature of the indoor space reaches the set temperature, each of the performance suppression rates indicating a degree of suppression of air conditioning performance of the air conditioner, and
• the control unit controls the air conditioner based on a performance suppression rate minimizing the power consumption amount in the plurality of performance suppression rates.