Incandescent lighting is the most common, and least energy efficient, type of lighting used in homes. | Photo courtesy of ©iStockphoto/TokenPhoto.
Incandescent lighting is the most common type of lighting used in homes, though it is the least energy efficient. It has traditionally delivered about 85% of household illumination.
Incandescent lightbulbs operate without ballasts. They light up instantly, providing a warm light and excellent color rendition. You can also dim them. However, incandescent lamps have a low efficacy compared to other lighting options (10–17 lumens per watt) and a short average operating life (750–2500 hours).
Incandescent bulbs are the least expensive to buy, but because of their relative inefficiency and short life spans, they are more expensive to operate than newer lighting types such as CFLs and LEDs. Learn more about how energy-efficient lightbulbs compare with traditional incandescents and replacing incandescent lamps.
Types of Incandescent Lightbulbs
There are three common types of incandescent lightbulbs:
- Standard incandescent
- Energy-saving or halogen
Standard Incandescent Lightbulbs
Known as the screw-in "A"-type lightbulb, standard incandescent bulbs are the most common -- and most inefficient -- light source available. These bulbs produce light from a tiny coil of tungsten wire that glows when it is heated by an electrical current.
Larger wattage incandescent bulbs have a higher efficacy than smaller wattage bulbs. However, a larger wattage bulb may not be the most energy- or cost-effective option, depending on how much light you need.
"Long-life" bulbs, with thicker filaments, are a variation of these A-type bulbs. Although these bulbs last longer than their counterparts, they are less energy efficient.
Energy-Saving Incandescent (or Halogen) Lightbulbs
Halogen lamps -- a type of incandescent lighting with a capsule that holds gas around the filaments -- are more energy efficient than standard incandescent bulbs. They also provide excellent color rendition.
Learn more about halogens on Energy Basics.
Halogens are a little more expensive than incandescents, but are less expensive to operate because of their higher efficacy. They are commonly used in reflectors such as indoor and outdoor flood lighting, indoor recessed and track fixtures, and floor and desk lamps.
Some halogen bulbs are dimmable, as indicated on the package, and are compatible with timers and other lighting controls.
Reflector bulbs (Type R) spread and direct light over specific areas. They are used mainly for floodlighting, spotlighting, and downlighting.
There are two types of reflector lamps:
- Parabolic aluminized reflector lamps (Type PAR) are used for a number of applications, including outdoor floodlighting.
- Ellipsoidal reflector lamps (Type ER) focus light beams about 2 inches in front of its enclosure, projecting light down from recessed fixtures. Ellipsoidal reflectors are twice as energy efficient as parabolic reflectors for recessed fixtures.