High CRI LED lighting
The color rendering index (CRI) of a light source is a quantitative measure of its ability to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. It is significant because it has been the most difficult metric for incandescent replacement light bulbs to match (while maintaining high efficiency) and therefore the most frequently ignored. For that reason, LED light bulbs with a high CRI can be worthy replacements for incandescent light bulbs. Most LED lights do not have a CRI above 90.
However, CRI is a poor indicator of the perception of light produced by LEDs, and scores as low as 25 can produce vivid-appearing white light, while high-scoring sources can still be very poor at rendering reds, including skin tones.[2]
In 2008, the US Department of Energy created the L Prize to find an incandescent light bulb replacement that met efficiency metrics and had a CRI above 90.[3]
Glossary
- Base is the type of connector on the bulb. E26 is the standard American screw base.
- Color temp or color temperature is a measure of the frequency of light given off by the bulb. 2700 K is equivalent to a standard incandescent light. Sunlight's color temperature is 5780 K, but indoor lights with a color temperature this high will tend to look unnaturally blue to some. Generally any color temperature other than 2700 K will look unnatural in a home setting until people become used to the higher color temperatures.
- CRI is a measure of how natural the light given off by the bulb looks in comparison to a broad spectrum light source.
- Dimmability Whether or not the bulb's brightness can be controlled by a dimmer. Most high-CRI LED bulbs are made with the circuitry to allow them to be dimmed with standard dimmer switches. Some are not able to be dimmed with a wall dimmer, but instead are controlled over a wireless network with a device like a smartphone.
- Efficacy or lumens per-watt is a measure of the efficiency with which the bulb produces light. It is not a measure of the effectiveness of the light. For instance, a ceiling-mounted bulb that directs all light downward will be more effective than a bulb inside a lamp shade that absorbs a large portion of the light. The maximum possible value for any light source is 683. The maximum possible value for LED lighting is 300.
- Form factor is the shape of the light bulb. A19 is the traditional light bulb shape.
- Incandescent equivalent is the number of watts an equivalent incandescent bulb would consume.
- Lifespan is an estimate of the amount of time the bulb can be on before it stops working. Another related metric is "lumen maintenance", which is a measure of the brightness of the bulb at the end of its life compared to its brightness at the beginning. It is not generally advertised but can range from 70% brightness to close to 100%.
- Lumens is a measure of the light given off by the bulb. The direction in which light is emitted may change how much light is usable.
- R9 is CRI for red color.
- Watts is the amount of power the bulb consumes at full brightness.
See also
References
- ↑ "LED 12.5W A19 Soft White 12.5W (60W) Dimmable A19". Energy-saving light bulbs. Philips. Retrieved 2014-04-18.
- ↑ Baier, Simon. "Is Color Quality Scale (CQS) an improvement on CRI?". Lumenistics web site. Retrieved 2013-09-09.
- ↑ "L-Prize - Bright Tomorrow Lighting Prizes - Competition Overview". Lightingprize.org. November 7, 2012. Retrieved 2014-04-18.