One major advantage LED has over other traditional light sources is dimmability.  Most LED lamps and luminaires are dimmable without the need for a special driver or ballast.  Many other light sources require a special lamp, or ballast in order to dim.

Comparing LED downlights to the previous industry standard, compact fluorescent, a dimmable LED downlight was superior to a non-dimmable compact fluorescent downlight in almost every aspect.  The LED was available in a wider variety of color temperatures, lumen outputs, used less energy, had a longer lamp life.  The lone advantage the compact fluorescent option held over the LED downlight was cost.

However, if we compared a dimmable compact fluorescent to a standard LED, the cost was relatively similar.  Even in the early days of LED, if a project called for dimmable downlights, compact fluorescent could not compete with LED in cost because of the inherent dimmability of most LED downlights, and the additional cost required to make compact fluorescent downlights dimmable.

As technology has evolved, the cost of LED downlights, and LED luminaries in general, has gone down, virtually eliminating the cost advantage fluorescent once realized over LED.

Another advantage that LED holds over fluorescent is “strobe-ability”.  An LED can be strobed, or turned on and off quickly, with no effect on the overall life of the LED.  Strobing fluorescent lamps, however, has a detritus effect on the life of the lamp.  In fact, the general recommendations for fluorescent lighting, are that once they have been turned on, they should remain on for 2 hours in order to achieve maximum lamp life.  In many areas, such as an open office, a retail store, or a place of business, this might not have any effect, as most lights are left on during the day, and turned off at night. However, even in those types of spaces (e.g. closets, bathrooms), areas controlled with motion sensors, etc., would suffer loss of lamp life if illuminated with fluorescent lighting.

Exterior lighting can also use the dimmability of LED lighting to an advantage.  While LEDs offer energy savings compared to traditional HID sources, LED can also contribute to additional energy savings via the use of step-dimming.  Step dimming is two or three pre-set lighting levels that are triggered by external cues.  For example, in a parking lot, all fixtures might be set to 100% from 5 pm-midnight.  Then, at midnight, the light levels drop to 50%, allowing security level light levels, but with an additional 50% reduction in energy costs.  Step dimming is an inherent benefit of the standard dimmability of LED lighting that is not available in standard HID products without additional cost, degradation in life, color, and lumen output.

Finally, LEDs are “instant on”.  HID and fluorescent lamps generally require a “warm up” period before they reach 100% output.  LEDs do not require a warm up, and are at 100% output immediately.

LEDs hold a functional advantage over most traditional light sources.