and integration into buildings and electricity systems. Chapter 5 provides a perspective on the design and installation of LED and OLED luminaires. Chapter 6 discusses the market barriers to the adoption of SSL products.
There are many different kinds of lamps. Most of the lamps used in residential applications are omnidirectional (emit light in all directions) incandescent lamps, typically with a medium screw base (Figure 1.12) that fits into most residential luminaires. In addition, there are candelabra and intermediate base lamps that are commonly used in residential applications, especially in chandeliers and wall sconces. Incandescent lamps produce light by heating a tungsten filament to a temperature of approximately 2,500 K to 3,000 K where the filament glows or incandesces.
Halogen lamps are incandescent lamps in which the tungsten filament has been enclosed in a capsule containing a halogen gas, typically bromine, which allows the filament to operate at a slightly higher temperature without reducing the rated life and resulting in a somewhat higher light output than the standard incandescent lamp. Halogen lamps are available that emit light omnidirectionally, as well as directional varieties, often known as reflector lamps. Reflector lamps are designated by the properties of their reflectors, such as PAR (parabolic aluminized reflector (Figure 1.13) or MR (multifaceted mirror reflector), and are most commonly either standard incandescent or halogen. The low-voltage MR-16 lamp (Figure 1.14) commonly used in accent, task, and display lighting uses halogen technology.
FIGURE 1.12 Incandescent with medium screwbase (A-19).
Fluorescent lamps are available in a range of shapes and sizes. Linear fluorescent lamps are frequently used in commercial spaces (offices, stores) and are typically long 4-foot tubes. They are often installed in recessed luminaires in the ceiling or are pendant-mounted from the ceiling. All fluorescent lamps require a ballast. CFLs are available with screw bases and an integral ballast (Figure 1.15) for use as replacements for incandescent lamps or with pin bases for use with a separate ballast (Figure 1.16). Both CFLs and linear fluorescent lamps produce light by exciting phosphors, which then fluoresce, with ultraviolet energy. A small amount of mercury is added to the lamp to emit ultraviolet light at a suitable wavelength for exciting the phosphor.
High-intensity-discharge (HID) lamps are electric lamps with tubes filled with gas and metal salts. The gas initiates an arc, which evaporates the metal salts, forming a plasma. This results in an efficient and high-intensity light source. These lamps are suitable for both indoor and outdoor applications and are generally used to light large spaces or roadways. All HID lamps require a ballast.
Mercury vapor, metal halide (Figure 1.17), and high-pressure sodium lamps are examples of specific types of HID lamps. HID lamps require a warm-up period to reach stable output as well as a cool-down period before restarting.
FIGURE 1.13 PAR 20 lamp (tungsten halogen).