The present invention relates to an energy management system. The energy management system includes: a client device; and a server. The server includes: a communication unit configured to communicate with the client device; a processor configured to perform a process requested by the client device; a storage unit in which data related to control and management of the energy management system; and a controller configured to control the processor to classify a plurality of tasks included in a first process according to a predetermined criterion, create a plurality of second processes from the first process, and process the plurality of second processes by referring to the data. If a load is weighted on a second process performing a predetermined task, the controller is further configured to control the processor to additionally create another second process performing the predetermined task.