This chapter provides an overview of HVAC system applications across various building types, including residential, commercial, and industrial settings. It explores the design considerations for each application, emphasizing energy efficiency, occupant comfort, and system reliability. The chapter also compares common HVAC systems such as split systems, variable refrigerant flow (VRF) systems, and centralized chilled water plants, highlighting their advantages, limitations, and suitability for different scenarios. It offers insights into selecting the right system based on factors like building size, climate, and operational requirements.