Light emitting diodes (LED) technology has grown to rival the most efficient white light sources, and the benefits are great, but just how efficient are LEDs?
First measure is color quality. LEDs have very high correlated color temperatures (CCTs), often above 5000K for a cold bluish light. However, warm white LEDs (2600K to 3500K) have improved significantly. The color rendering of LED bulbs are 80 CRI, equivalent to CFLs.
Fluorescent and high-intensity discharge (HID) light sources cannot function without a ballast, which provides a starting voltage and limits electrical current to the lamp. Similarly, LEDs require a power supply, or a “driver.” This is a second way to determine LED efficiency.
Directional light sources are another important factor when considering the efficiency of a light. LEDs potentially have higher application efficiency due to the directional nature of their light emission. LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light.
Energy efficiency of light sources is typically measured in lumens per watt (lm/W), or the amount of light produced for each watt of electricity consumed.