Room for improvement calculation apparatus and a control method thereof, and room for improvement amount calculation program

An energy consumption improvement calculation apparatus calculates an amount of room-for-improvement that is an improvable amount of power consumption of at least one target device. A cycle use section (42) of the energy consumption improvement calculation apparatus uses measured values (E') and measurement times (t') of power consumption and a fluctuating cycle (±cycle) of power consumption which fluctuates periodically. The cycle use section (42) includes: a phase determining section (62) for determining a phase (1) of the measurement time (t') with respect to one cycle; a table generating section (63) for calculating a reference value which is an average of plural ones of the measured values (E') measured at measurement times (t') corresponding to the phase (1) and generating a correspondence table (65) between each phase and the reference value; and a subtraction section (64) for subtracting, from a measured value (E') measured at a given measurement time, a reference value corresponding to a phase of the given measurement time and obtained by the phase determining section (62) and the correspondence table (65). The subtraction result gives the amount of room-for-improvement (”Ec) at the given measurement time (t').