Color rendering index (CRI)
The color rendering index measures the ability of a light source to render colors, compared to either incandescent reference sources if warm in color, or daylight reference sources if cooler in color. At the maximum CRI value of 100, the colors of objects would be seen as they would appear under an incandescent or daylight spectrum of the same CCT. In general, a minimum CRI of 80 is recommended for interior lighting, with CRIs of 90 or higher indicating excellent color rendering. ENERGY STAR requires that qualified fixtures have lamps with CRI above 80.
The CRI has been found to be inaccurate for RGB (red, green, blue) LED systems because it's poor at predicting the quality of the appearance of saturated color objects, and doesn't correspond well to human perception of color quality. Hence, CCT and CRI together give only an approximate figure for selecting and matching lamp colors. A number of new color-rendering metrics have been proposed in recent years, but none have been widely adopted as of yet. In the meantime, color rendering of LED lighting product should be evaluated in person and in the intended application if possible.
Energy Use and Luminous Efficacy
Luminous efficacy is a measure of how efficient a light source produces visible light and is the ratio of the light output of a lamp (lumens) to its active power (watts). LED lighting have higher luminous efficacy when compared to other lighting technologies. While buying lamps consumers should pay more attention to the luminous efficacy i.e. amount of light the lamp produces per watt than the actual wattage of the lamp. Lamps with higher lumens per watt have higher efficiency. Table 1 shows the luminous efficacy comparison of different lighting technologies.
