PURPOSE: To standardize operation modes and save energy by a method wherein a variable based on the outdoor temperature and humidity, weather, and the speciality of the day is added to the standard load pattern of the day calculated by a computer to obtain a forecast load value, and the operating number of equipment and the equipment number corresponding to the forecast load value and the present load are decided and instructed.
CONSTITUTION: A standard load pattern arithmetic device 10 calculates the standard load pattern of the day based on the reference temperatures and humidity through the year, past operation records of refrigerating machines and boilers in resemble regions and other data, and a correction factor input device 11 prepares a fluctuation weighing factor table for the load fluctuation factors such as the outdoor temperature and humidity, weather, the day of week, a special period and others and decides a fluctuation factor. The arithmetic device 10 measures the sum of actual loads of refrigerating machines, etc., and obtains the load demand forecast values for 24 hours from the standard load pattern, fluctuation factor, the fluctuation trend of actual load before the present time. The capacity of the refrigerating machines in operation at present is compared with the actual load at present and the load forecast value in succeeding time period, and the numbers of machines to be started or stopped are decided. Thereby, energy saving and standardiztion of operation can be attained by operation number control according to various conditions.