Many different approaches are currently used in the field of network integrated control systems known as the Smart Grid. We implemented an energy management system with the aim of developing a future standard for this area. It is difficult to connect a heterogeneous system containing different standards, even if standardized technologies are available. A metastandard concept is proposed and substantiated to overcome this problem. The concept was substantiated in an energy management system constructed at the Fukue port terminal building in Goto City, Nagasaki Prefecture. This system uses a variety of devices produced by seven different companies. An air-conditioning control system to reduce carbon dioxide emissions was implemented and substantiated as an application of the proposed system. Our results demonstrate the effects of a common platform and its advantages.