FAQ: “White LED sources are becoming popular now while incandescent lamps tend to be replaced by energy saving, fluorescent lamps. Will CIE release new illuminants for LED sources as it was done in the past for daylight, incandescent and fluorescent sources?”
Two of the challenges in developing illuminants to represent white LEDs or full spectrum white mixtures of LEDs are:
- Until relatively recently LED technology has been changing so rapidly, particularly with the advent of white LEDs, it was difficult to standardize the spectral power distributions.
- There has been considerable variation in LED lamps and output among different manufacturers.
At the moment, at least with consumer LED products, there general consensus among manufacturers appears to have developed on a full spectrum white LED based on color temperature - warm
As a workaround until something more official from the CIE becomes available, for the calculation of color values you could select the closest full spectrum illuminant (no F series; just A and D) similar to the color temperature rating of the LED you are trying to approximate.
For very warm consumer LED lamps around 3000 K designed to replace halogen lamps, use illuminant A.
For cooler daylight-balanced LED lamps for home or office, there are typically 3 levels.
- Warm daylight in the 5000 – 6000 K range; use D55
- Natural daylight in the 6500 K; use D65.
- Cool daylight around 7500 K; use D75.
- As a default, use D65 as the general case.