ABSTRACT
This chapter provides a general background into building energy systems with photos and sketches to illustrate the variety of HVAC systems and equipment. The anatomy of a building’s HVAC system consists of four main parts: (1) primary systems or central plant, (2) distribution system, (3) terminal devices, and (4) controls. Recall that conditioning a space involves cooling or heating and providing adequate conditioned ventilation air to the space. Secondary systems are those that distribute the cooling (or heating) thermal energy produced by the primary systems, namely the chillers (or boilers), to the building spaces needing to be conditioned. This can be done using either water or air as the working fluid, and so it is common to recognize three generic types of secondary systems, namely, all-water, all-air, and air-water systems. Alternatively, HVAC systems can also be categorized into three groups: unitary, centralized, and district. The heating and cooling energy is then transferred to the room air by distribution systems. An important, and often neglected, aspect is the control system that maintains proper functioning of the various components of the HVAC system. We describe each of these system categories at length along with discussion and photographs or sketches of a few pertinent components. The material in this chapter would be useful to a reader with limited practical knowledge of these systems since it would allow him/her to visualize the equipment or system while it is being discussed both qualitatively and in an analytical framework in the remaining chapters of this book.
