Understanding Light Color
By Sally Gillie
Electric Mirror uses CRI 85 or higher T5 fluorescent lamps in our Lighted Mirrors at 3,000 Kelvin which gives the most optimum and natural light color. The result of this are fantastic products that are better and more similar to natural daylight than any of our competitors.
Lighting Sources and Color
Understanding light quality can be a challenge, especially with the variety of light sources today. If you’ve swapped out a traditional incandescent bulb for one of the new long-lasting compact fluorescents, you may have noticed a difference in light color.
This is where the Kelvin scale comes into play.
Light Color and the Kelvin Scale
Kelvin is a unit of measurement used to describe the hue of a specific light source. This is not necessarily related to the heat output of the light source but rather the color of the light output. The higher the Kelvin value of the light source, the closer the light’s color output will be to actual sunlight, as this chart indicates.
Light output at 5,000K to 10,000K is at the high, bluer end of the scale and may seem overly bright for some indoor settings. Lower Kelvin temperatures in the 2,700K to 3,500K range cast a warmer, yellower-toned light. On the extreme low end, think of the orange-red glow of a match flame; the high end can be compared to a bright daylight sky.
Mid-range lighting from about 2700K to 3500K has been shown over time to be the preferred level of lighting for most homes, offices and public indoor spaces such as libraries and schools. Higher levels of more than 4,000K to 5,000K may be suitable for business display cases, or museums, where a brighter light may be useful.
Color Rendering Index
Another way to assess light quality is through the Color Rendering Index, or CRI. This measurement does not address the light itself, but how accurately a light source renders colors and shades of color to the human eye. The best source for rendering color is full daylight, which not only accurately reflects colors but also captures all of their subtle variations. A CRI rating of 100% is the highest rating and comparable to full sunlight. A low CRI rating of less than 20% will have very little color accuracy.
The average human eye is incredibly sensitive to color wavelengths and can discern many thousands of color variations. The visible light spectrum, through which we can see all light and colors, is limited to those wavelengths in the spectrum that lie between ultrared (longer wavelengths) and ultraviolet light (shorter wavelengths).
Differences between CRI and the Kelvin Scale
It’s important to remember that the characteristics of light, as measured on the Kelvin scale and the CRI, are very different from each other.
The Kelvin scale indicates the color appearance of the light source and the color of the light it throws. The CRI rating tells how well the light renders colors to the human eye. Fluorescent lamps can have CRI ratings anywhere from 52 to more than 90 depending on the lamp type.
According to Energy Star, a voluntary government program administered through the US Environmental Protection Agency, a CRI rating above 80 offers very good color rendering and is preferable for use within the home. Lighting sources that offer optimum CRI ratings include fluorescents, incandescents and tungsten-halogens.
Until the last few years, incandescent bulbs were the standard choice for home lighting needs for both its warm cast and high CRI abilities. Fluorescent lamps, which tended to be of the old industry-standard 4200K variety, had poor color rendering ability and did not appeal to the residential market.
Thanks to major advances in fluorescent technology, that’s no longer the case.
Fluorescent tubes, such as in the newer T5 fluorescents, have excellent color rendering abilities. These are due to their triphosphor coating which is applied to the lamp, giving it such advantages as brighter light levels, extended lamp life, reduced energy and maintenance costs and better color rendering. These lamps are often described as T5’s or T8’s, with the T standing for tubular and the number referring to the diameter of the lamp. A T5, for example, is 5/8” in diameter, while a T8 is 1”.
Electric Mirror uses CRI 85 T5 fuorescent lamps at 3,000 Kelvin, which is the optimum combination!