One of the most important factors in the efficiency of any HVAC system is the selection and implementation of the proper control sequence of operations.
We almost always think about the BAS as a tool that is a critical part of energy management, so these systems are typically focused on those systems that directly use energy — notably the HVAC and lighting systems.
Generally, when we think about BAS, it is in the context of large commercial buildings, those well over 25,000 sq ft. According to the latest government data though (from the 2012 Commercial Building Energy Consumption Survey), 88% of all commercial buildings are 25,000 sq ft or less.