LED compared to other Lighting Technologies

• Incandescent lamps (light bulbs) create light by running electricity through a resistive filament, thereby heating the filament to a very high temperature so that it glows and produces visible light. A broad range of visible frequencies are naturally produced, yielding a pleasing warm yellow or white color quality. Incandescent light however, is highly inefficient, as over 98% of the energy input is emitted as heat. A 100 watt 120 VAC light bulb produces about 1,700 lumens, about 17 lumens per watt. Incandescent lamps are relatively inexpensive to produce. The typical lifespan of a mains incandescent lamp is around 1,000 hours. They work well with dimmers. Most existing light fixtures are designed for the size and shape of these traditional bulbs.

• Fluorescent lamps (light bulbs) work by passing electricity through mercury vapor, which in turn produces ultraviolet light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. While the heat generated by fluorescent lamps is much less than its incandescent counterpart, energy is still lost in generating the ultraviolet light and converting this light into visible light. If the lamp breaks exposure to mercury can occur. Linear fluorescent lamps are typically five to six times the cost of incandescent lamps, but have life spans around 10,000 and 20,000 hours. Lifetime varies from 1,200 hours to 20,000 hours for compact fluorescent lamps.

• Fluorescent tubes with modern electronic ballasts commonly average 50 to 67 lm/W overall. Most compact fluorescents rated at 13 watts or more with integral electronic ballasts achieve about 60 lumens/watt. Those with "iron" ballasts flicker at 100 or 120 Hz, and are less efficient. Most fluorescent luminaires are not compatible with dimmers. The quality of the light tends to be a harsh white because of the lack of a broad band of frequencies. To prevent mercury release, fluorescent tubes should be recycled by specialist routes rather than included in general refuse.

• SSL/LEDs LEDs come in multiple colors, which are produced without the need for filters. A white SSL can comprise a single high-power LED, multiple white LEDs, or LEDs of different colors mixed to produce white light.
  
  Advantages include:
  
  
  • High efficiency - LEDs are now available that reliably offer over 100 lumens from a one-watt device, or much higher outputs at higher drive currents
  • Small size - provides design flexibility, arranged in rows, rings, clusters, or individual points
  • High durability - no filament or tube to break
  • Life span - in properly engineered lamps, LEDs can last 50,000 - 60,000 hours
  • Full dimmability – unlike fluorescent lamps, LEDs can be dimmed using pulse-width modulation (PWM - turning the light on and off very quickly at varying intervals). This also allows full color mixing in lamps with LEDs of different colors.
  • Mercury-free - unlike fluorescent and most HID technologies, LEDs contain no hazardous mercury or halogen gases

However, some current models are not compatible with standard dimmers. It is not currently practical to produce high levels of room lighting. As a result, current LED screw-in light bulbs offer either low levels of light at a moderate cost, or moderate levels of light at a high cost. In contrast to other lighting technologies, LED light tends to be directional. This is a disadvantage for most general lighting applications, but can be an advantage for spot or flood lighting.

Because individual LEDs are low-voltage DC devices, implementing SSL to operate from mains AC requires well designed circuitry and a thermal case to dissipate the heat.