(BMS) is a computer-based control system installed in buildings that controls and monitors the building’s
mechanical and electrical equipment such as ventilation, lighting, power systems, fire systems, and security
systems. It is most common in a large building. Its core function is to manage the environment within the
building and may control temperature, carbon dioxide levels and humidity within a building. As a core function
in most BMS systems, it controls heating and cooling, manages the systems that distribute this air throughout
the building (for example by operating fans or opening/closing dampers), and then locally controls the mixture
of heating and cooling to achieve the desired room temperature. A secondary function sometimes is to
monitor the level of human-generated CO2, mixing in outside air with waste air to increase the amount of
oxygen while also minimizing heat/cooling losses. Systems linked to a BMS typically represent 40% of a
building’s energy usage; if lighting is included, this number approaches 70%. BMS systems are a critical
component to managing energy demand. As well as controlling the building’s internal environment, BMS
systems are sometimes linked to access control (turnstiles and access doors controlling who is allowed access
and egress to the building) or other security systems such as closed-circuit television (CCTV) and motion
detectors. Fire alarm systems and elevators are also sometimes linked to a BMS, for example, if a fire is
detected then the system could shut off dampers in the ventilation system to stop smoke spreading and send
all the elevators to the ground floor and park them to prevent people from using them in the event of a fire.