In this chapter, we delve deeper into understanding modeling and control approaches for one of the important subsystems in an intelligent building, the HVAC system. Specifically, Vapor Compression Systems (VCS) are the primary energy systems in building air conditioning, heat pump, and refrigeration systems. We will discuss standard methods for constructing dynamic models of vapor compression systems, and their relative advantages for analysis, design, control design, and fault detection. The principal interests are moving boundary and finite-volume approaches to capture the salient dynamics of two-phase flow heat exchangers. We will present modeling approaches for auxiliary equipment, such as, valves, compressors, fans, dampers, and heating/cooling coils, allowing the reader to understand the construction of typical HVAC system models. We will then highlight limitations of such models and address advanced modeling approaches for challenging transient scenarios. Finally, we give a summary of single-input, single-output control strategies for HVAC system, with simulation and experimental examples to illustrate their effectiveness.