Have you ever seen a colored light bulb? Have you seen the effect that bulb has on the items it’s illuminating? Halloween is coming up. If you haven’t seen it, try a black or orange light bulb and study how it affects the colors of what it’s illuminating. Inherently, based on the type of light bulb, the light generated from that bulb has a color. In the world of lighting, that color is measured on the Color Rendering Index (CRI).
The peak of the CRI is 100. To give you an example, noon day sun would best fit this description. Remember, it’s not the color of the sun. It is how well the sun’s light reflects the truest color of an object. According to this index, poor color (where colors do not show) is 79 or lower. Good color is achieved from 80 – 94 and great color at 95 plus. The following are common bulbs, their CRI, and their common uses, and average bulb life.
Quartz Halogen – CRI: 100!
Quartz halogen bulbs have a perfect CRI of 100 and they are long lasting also – anywhere from 2,000 – 4,000 hours. These bulbs are used in the automotive industry as well as in residential indoor and outdoor lighting, and commercial lighting
Ceramic Metal Halide – CRI: 96
At nearly a perfect score, ceramic metal halide has an incredibly long bulb life – 12,000 – 20,000 hours. If you used ceramic metal halide bulbs for your outdoor lighting and ran the lights 12 hours each night, the bulb would last 3-5 years! Ceramic metal halide bulbs are used in residential as well as commercial lighting settings
Metal Halide – CRI: 80+
Although the CRI of metal halide is significantly lower, it still has a phenomenal bulb life of 12,000 – 20,000 hours. Metal halide bulbs are used for both residential and commercial lighting applications.
LED – CRI: 50
So here is where the green bulb comes into play. LED bulb Life is 25,000 – 50,000 hours. The bulb life is what makes it so green. Unfortunately with a lower CRI, the lighting effect does not reflect the truest color of the object it’s illuminating.
I am in full agreement that energy savings is a good thing. However, considering color, I’m not ready to anoint LED king just yet. To understand the importance of color, we first need to understand how it is gauged. The CRI or Color Rendering Index measures how well a light source emits a broad, complete spectrum of visible color. In laymen terms, how light reflects off of a source.