Types of Lighting

There are several basic types of lighting. Each type varies widely in their construction, efficiency, color characteristics, and lamp life:

• Incandescent – Used primarily in residential indoor lighting systems
• Fluorescent – Used primarily in commercial indoor lighting systems
• High-Intensity Discharge – Used only for outdoor lighting applications
• Low-Pressure Sodium – Used where color rendering is not important, such as highway and security lighting.
• Light-Emitting Diodes (LED) - An emerging technology that spans many applications, but is primarily found in specialty settings where lower light levels are acceptable.

Incandescent Lamps
Incandescent lamps are the least expensive to buy but the most expensive to operate. Incandescent light is produced by a tiny coil of tungsten wire that glows when it is heated by an electrical current. Incandescent lamps have the shortest lives of the common lighting types. They are also relatively inefficient compared with other lighting types. However, significant energy and cost savings are possible if you select the right incandescent lamp for the right job. The three most common types of incandescent lights are standard incandescent, tungsten halogen, and reflector lamps.

Types of Incandescent Lamps include:

• Standard Incandescent  – “A-type light bulb,” the most common yet the most inefficient light source available. “Long- life” bulbs, with thicker filaments, are a variation of these A-type bulbs. Although long-life bulbs last longer than their regular counterparts, they are less energy efficient. 
• Tungsten Halogen – A newer type of incandescent lighting that achieves better energy efficiency than standard A-type bulbs. It has a gas filling and an inner coating that reflect heat. Together, the filling and coating recycle heat to keep the filament hot with less electricity. These lamps are considerably more expensive than standard incandescents and are primarily used in commercial applications: theater, store, and outdoor lighting systems.
• Reflector Lamps – There are 3 styles of reflector lamps:
  • Type R reflectors are designed to spread light over specific areas. They are used mainly indoors for stage/theater and store applications, as well as floodlighting, spotlighting, and downlighting. 
  • Parabolic aluminized reflectors (Type PAR) are used for outdoor floodlighting. 
  • Ellipsoidal reflector (Type ER) focuses the light beam about 2 inches (5 centimeters) in front of its enclosure and is designed to project light down from recessed fixtures. Twice as energy efficient as parabolic reflectors for recessed fixtures.

Fluorescent Lamps

The light produced by a fluorescent tube is caused by an electric current conducted through mercury and inert gases. Fluorescent lighting is used mainly indoors — both for ambient and task lighting —and is about 3 to 4 times as efficient as incandescent lighting.

Fluorescent lamps last about 10 times longer than incandescents. But, to gain the most efficiency, you should install fluorescents in places where they will be on for several hours at a time.

Fluorescent lights require ballasts for starting and circuit protection. A ballast is a device that controls the electricity used by the unit. You can increase the energy savings for existing fluorescent lighting by relamping (e.g., replacing an existing lamp with one of a lower wattage), replacing magnetic ballasts with electronic versions, and replacing fixtures with more efficient models.

Types of Fluorescent Lamps include:

• Light-Fluorescent T5 and T8 Type Fluorescent Fittings and Lamps (tubes) - Tube fluorescent lamps are the next most popular lamps after A-type incandescent lamps. The two most common types are 40-watt, 4-foot (1.2-meter) lamps and 75-watt, 8-foot (2.4-meter) lamps. Tubular fluorescent fixtures and lamps are preferred for ambient lighting in large indoor areas because their low brightness creates less direct glare than do incandescent bulbs. These types of fittings can use either linear or a more decorative circular shaped lamps. 
• Light-CFL Compact fluorescent lamps (CFLs) - The most significant lighting advance developed for homes in recent years. They combine the efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures. CFLs come in integral and modular designs. Integral CFLs have a ballast and a lamp in a single disposable unit. Modular designs feature a separate ballast that serves about five lamp replacements before it wears out. CFLs come in a variety of sizes and shapes, (as seen in the picture below), including (a) twin-tube integral, (b and c) triple-tube integral, (d) integral model with casing that reduces glare, (e) modular circline and ballast, and (f) modular quad-tube and ballast.

High-intensity discharge (HID)

High-intensity discharge (HID) lamps provide the highest efficacy and longest service life of any lighting type. HID lamps use an electric arc to produce intense light. They also require ballasts, and they take a few seconds to produce light when first turned on because the ballast needs time to establish the electric arc. The three most common types of HID lamps are mercury vapor, metal halide, and high-pressure sodium. HID lamps and fixtures can save 75% to 90% of lighting energy when they replace incandescent lamps and fixtures. Significant energy savings are possible by replacing old mercury vapor lamps with newer metal halide or high-pressure sodium lamps.

Types of HID lamps include:

• Mercury vapor – The oldest type of HID lighting, it is primarily used for street lighting. Mercury vapor lamps cast a very cool blue/green white light and provide provide about 50 lumens per watt.
• Metal halide lamps – Similar in construction and appearance to mercury vapor lamps, but with the addition of metal halide gases to mercury gas within the lamp. This results in higher light output, more lumens per watt, and better color rendition than from mercury gas alone.  Used to light large indoor areas such as gymnasiums and sports arenas, and for outdoor areas such as car lots or anywhere that color rendition is important. 
• High pressure sodium – The most common type of outdoor lighting these lamps give a warm white color. The color rendition ranges from poor to fairly good depending on design and intended use. These lamps are reliable, have long service lives, and provide 90 to 150 lumens per watt — an efficiency exceeded only by low pressure sodium lighting.  

Low-pressure sodium

Low-pressure sodium lamps work somewhat like fluorescent lamps. They are the most efficient artificial lighting, have the longest service life, and maintain their light output better than any other lamp type. Low-pressure sodium lighting is used where color is not important because it renders all colors as tones of yellow or gray. Typical applications include highway and security lighting.

Light-Emitting Diodes (LEDs)

LEDs are solid state, semiconductor light sources. Light is produced when electrons pass through a semiconductor material. Current commercial LED light fixtures are about as efficient as compact fluorescents (CFLs). However, LED lighting is a relatively new commercial lighting technology that is in a constant state of development. There is hope that with continued research and development, LED light sources will surpass fluorescent light sources in terms of cost, efficiency and overall utility. When lighting sources and their fixtures are designed together, LEDs have an advantage over CFLs in their ability to place light where desired, rather than lost within the fixture itself.

Visit our LED webpage for more information.