ABSTRACT
This chapter starts with manual controls and proceeds through timers, programmable controllers, and digital computers. Lights have on-off wall switches or panel switches, and some have timers and dimmer controls. In a true distributed control system, the remote controllers can function with or without the central unit-at least for a period of time. The energy management control system of old relied heavily on a collection of separate systems that operated independently, and often with proprietary communication protocols that made expansion, modification, updating and integration with other building or plant information and control systems very cumbersome, if impossible. Energy use can be controlled in order to reduce costs and maximize profits. The controls can be as simple as manually turning off a switch, but often automated controls ranging from simple clocks to sophisticated computers are required. Computers have become so inexpensive and so powerful that they are used everywhere today, including use in a wide variety of tasks in energy management and energy analysis.
