For those specifying color characteristics of light sources, a few words of caution: While color temperature and CRI are important, the true complexities of a light source’s color characteristics cannot be captured with a few numbers, which is why there is no substitute for seeing the lamps in a given application. A separate mockup with each proposed lamp type is encouraged because color quality is altered by room colors, luminaire characteristics, whether daylight is present, light levels and surface reflectances.
Further, different manufacturers may rate their products very similarly, but when these lamps are seen side by side, there may be slight differences, which is why manufacturers advise against mixing lamps from different manufacturers in the same application. Typically, the human eye cannot discern differences in CRI values that are up to 3-5 points apart.
If task lighting is added to the design, make sure the lamp color matches the general lighting. If the project is a retrofit, the specifier may neglect to specify color characteristics, which can result in poor quality, so even for projects that are driven by energy, lamp color quality should be given due priority and specified. Note the impacts of daylight (does not mix well with warm light sources), color transmission quality of the window glass (can distort color quality in the space), and color shift in the source during normal aging and dimming (such as white-light LED luminaires, which shift in color as they age).
Finally, the proliferation of color temperatures available in fluorescent lighting has made it easy to make mistakes such as mixing warm and cool lamps in the same application, which is why a maintenance plan, which includes a lamp schedule, is important to maintain design integrity.
Besides source color, consider the colors used in the room surface finishes, furnishings, partitions, etc. in the space. Lighter (non-glossy) colors are more reflective (but not glaring), which can raise average light levels and reduce demand on the lighting system. For this reason, lighter colors are recommended for large area surfaces in many typical applications such as offices and schools, while darker finishes are recommended to be limited to accents.
