In a method for monitoring power, preset information that defines periods in which one or more preset electric devices are scheduled to operate is received, an amount of power available, which is an estimated amount of power available in the building in each period, is calculated, estimated power consumption, which is estimated power consumption in the building in each period, is calculated using power consumption information, to which power consumption of the electric devices to be preset is registered in advance, and the preset information, an alternative instruction with which the estimated power consumption becomes lower than or equal to the amount of power available is generated, and the alternative instruction is displayed on a terminal apparatus. And at least one of the receiving, the calculating the amount of power available, the calculating the estimated power consumption, the generating and the displaying is performed by a processor.