Improving the energy performance of buildings will be essential for countries around the world to reduce energy consumption and emissions. Building automation and control systems (BACS) play a crucial role in achieving this objective. Heating, ventilating and air conditioning (HVAC) systems are primary targets for improving energy efficiency through automation. In tropical and subtropical regions with high average temperatures cooling in commercial buildings such as offices has become essential for thermal comfort. This paper focuses on a comprehensive understanding of building automation and control systems as well as an analysis of their use in reducing HVAC energy consumption in commercial buildings utilizing available data and literature resources. A survey of 23+7 research papers and 2 books was carried out to understand the scope of HVAC energy optimization in commercial buildings with the use of BACS. The purpose of this paper is to raise awareness of these BACS systems and the significance of their application for energy optimization in buildings. The Heating, Ventilation, and Air Conditioning (HVAC) system of a commercial building is one of the largest energy consumers, especially in tropical climates. Building automation and control systems (BACS) are one of the most important enabling technologies for energy-efficient HVAC control in buildings. Automated starting and stopping of HVAC equipment reduces system operating hours, maintenance costs, energy costs and greenhouse gas (GHG) emissions, thereby reducing the building's carbon footprint while maintaining occupant comfort. This results in savings in the thousands of dollars annually.