BAC systems, or Building Automation and Control systems, are automated systems within buildings which provide such things as:
Heating, Ventilation and Air Conditioning (HVAC)
Humidity and ventilation
Fire and smoke alarms and control
Flood safety
Lighting
Physical access (such as keycard or biometric entry systems)
Room automation
Buildings with BAC systems are often called intelligent buildings or smart buildings.
BAC systems are safety-critical systems. However, many BAC systems are internet-connected, and are subject to cyber-security threats.
BAC systems, are sometimes just known as Building Automation Systems (BAS) or Building Management Systems (BMS).