A Building Management System (BMS) is a comprehensive computer system. Once installed, the BMS communicates with all of the equipment and systems currently installed in the building. 

With a BMS, owners can monitor and manage core systems, such as air conditioning, heating, ventilation, lighting, or energy supply systems. Dealing with multiple energy sources, such as electricity, gas, and rooftop solar panels? A good BMS integrates each system individually, giving owners complete control over each supply.

The term building automation system (BAS) is also sometimes used to refer to BMS, highlighting the fact that a BMS rarely requires active input once set up correctly, and is largely automated. But BAS is more often used to refer to BMS systems applied on a larger scale, e.g. to condominiums, tertiary buildings, and public buildings, as part of a full-fledged automation and control system.