In contemporary commercial buildings, energy efficiency has taken a focal point of sustainable business practices. HVAC systems are amongst the major energy consumers of all building systems, making up usually about 40-60% of total building energy use. Hence, improving HVAC efficiency represents probably the biggest opportunity to reduce energy consumption, operational cost, comfort, and indoor air quality. This paper investigates the significant potential HVAC efficiency has with respect to commercial energy savings and various approaches for optimizing system performance.