ACG Certified Commissioning Authority (CxA) Practice Exam 2026 - Free CxA Practice Questions and Study Guide

BAS stands for Building Automation System. This is the centralized technology that brings together sensors, controllers, and software to monitor and automatically control a building’s main services—HVAC, lighting, shading, and power management. By coordinating these subsystems, a Building Automation System keeps occupants comfortable, saves energy, and streamlines building operations. The other terms point to security-focused functions—access control or alarms—and don’t capture the broad, integrated control of building services that BAS represents.