What is BAS (Building Automation System)?

building automation systemBuilding automation system is a programming, computerization, intelligent network of electronic equipment that monitors and controls mechanical systems and lighting systems in a building. Building Automation Systems (BAS) optimizes the start-up and performance of HVAC equipment and alarm systems. BAS adds in large amounts of interaction from the mechanical subsystems in the building, improves owner comfort, minimizes the energy used, and provides off-site building control. BAS-based computer controls to coordinate, organize, and optimize the control of subsystems on buildings such as security, fire / safety, elevators, and others.

Part of the system

  1. Controller

The controller used usually consists of one or more PLCs (Programmable Logic Controllers), with specific programming. The PLC in BAS is used to control the equipment normally used in a building.

  1. Occupancy Sensor

Occupancy is usually based on the time of the daily schedule. Override switches or sensors can be used to monitor occupancy in some internal areas of the building.

  1. Lighting

Lighting can be turned on or off with Building Automation System based on daily time, or timer and sensor. A simple example of such a system is to light a lamp in a room after half an hour of the last person out of the room.

  1. Air Handler

Air handler is used to regulate the exit of the air in the building. This arrangement is made to keep the air in accordance with the needs and human health in the building.

  1. Central Plant

Central Plant is needed to supply water-handling units with water.

  1. Alarms and Security

Many Building Automation Systems have alarm capabilities. If an alarm is detected, the alarm can be programmed to notify someone. Notifications can be made via computer, pager or alarm sound. The security system can be connected to the building automation system. If the occupancy sensor is present, then the sensor can also be used as a burglar alarm.


Building automated network consists of primary and secondary bus which consists of Programmable Logic Controllers, input / output and a user interface (human interface device). Primary and secondary bus can be fiber optic cable, ethernet, ARCNET, RS-232, RS-485 or wireless network. The controller is used with software that will work with BACnet, LanTalk, and ASHRAE standards. Input and output are analog and digital (binary). Analog input is used to read variable measurements. Digital input indicates when the device is on or not. The analog output controls the speed or position of the equipment, such as the variable frequency drive, an I-P transducer, or an actuator. Digital output is used to open and close relays and switches.