An air conditioning system includes air conditioning facilities with an indoor unit and an outdoor unit, a dedicated transmission line, a general-purpose equipment controller, and an energy management gateway. The energy management gateway includes a dedicated transmission line that enables communication with the air conditioning facilities via the dedicated transmission line, a management controller that collects management information preregistered for managing the air conditioning facilities from among various information received via the dedicated transmission line, and a processing controller that executes computational processing related to management of the air conditioning facilities on the basis of the collected management information, and controls the air conditioning facilities. The general-purpose equipment controller receives or accepts input of running information corresponding to each of the air conditioning facilities and general-purpose equipment, and controls the general-purpose equipment on the basis of the running information.