The architecture of light: architectural lighting design concepts and techniques. A textbook of procedures and practices for the architect, interior designer and lighting designer pdfdrive com

LAMP CODES FOR COLOR RENDERING INDEX (CRI) AND COLOR TEMPERATURE
It is important to point out that lamps truly are the core of all of our light creating devices. The design industry puts much focus on luminaires and their behaviors and aesthetic appeal, but at the heart of every electric light creating device is a lamp of some sort. It is perhaps more valuable to dedicate brain space to knowing about lamp technologies and properties than to clutter one’s head with the glut of luminaire literature that circulates. Lamp technology tends to change slower than luminaire technology, and there is an inherent logic to the way lamps are designed, marketed, and manufactured.
The key to successfully specifying the right lamp is caring tremendously
about Color Temperature and Color Rendering Index properties of the lamp. Remember that once we step outside of standard incandescent and halogen incandescent sources, science can cook up any color and color rendering properties desired. As per our earlier discussion, it is imperative to boil lamps down to their two primary properties of concern:
Color Rendering Index or CRI (from 1-100) Color Temperature (in Degrees Kelvin or Kelvins)
Luckily for us, most engineered electric light sources like HID and fluorescent are described by a three digit code that is stamped right on the lamp or lamp packaging. This three digit code contains information indicative of both the Color Rendering Index and Color Temperature.
The first number in the series indicates the Color Rendering Index or CRI.
If the 3-digit product code starts with a 7, the CRI of that product is in the 70’s. If the code starts with an 8, the CRI is in the 80’s. A 9 indicates a CRI in the 90’s. We tend to give more merit to the color-rendering capabilities of our fluorescent and HID sources, and so we can assess the CRI code like this:
7 = CRI in the 70’s: This is acceptable, but should be used only in non- color critical environments.