Building Control and Automation Systems

Abstract

<P>In industrialized societies, the comfort and productivity of people are influenced substantially by the quality of automation and control provided in the buildings in which they live and work. Accordingly, the history of building automation and control shows steady progress in complexity and capability. The first generation of systems used localized, stand-alone pneumatic controls. A major development in the 1950s, driven by the development of pneumatic sensor transmitters and receiver controllers, was pneumatic centralization. Electromechanical multiplexing systems, introduced in the 1960s, substantially reduced installation and maintenance costs and enabled automatic control of air-handling units for the first time. Minicomputers and programmable logic controllers (PLCs) became popular after the oil crisis in 1973 and helped spur the development of energy management systems. Today, the personal computer has revolutionized building control systems. Heating, ventilation, and air-conditioning (HVAC), lighting, elevators and escalators, and fire and security can now be integrated within one building automation system.</P> <P>In terms of basic control technologies, the PID controller remains dominant, especially for HVAC systems. PLCs are widely used for event-driven and sequencing operations such as start-up of chillers. With the maturing of local area network technologies and their widespread deployment for building automation, digital control loops can now be implemented throughout buildings. The infrastructure is available for implementing advanced algorithms.</P> <P>Much of this advanced technology is inspired by developments in artificial intelligence. Expert systems, neural networks, and fuzzy logic have all been used for some building control applications. (Tutorials on these methods can be found in Chapter 5.) Finally, the availability of inexpensive cameras and high-speed image processing electronics is permitting the use of vision-based sensing in building automation (and also in other fields-see Chapter 18 for a discussion of visual servoing in robotics). This could be used, for example, to estimate the number of residents within an air-conditioned space and regulate accordingly in response to ad hoc changes in the air-conditioned environment and to conserve energy.</P>