CCT describes chromaticity
Correlated color temperature relates a source chromaticity to a closest matching blackbody chromaticity. It is expressed in kelvin. It does not tell you the physical temperature of an LED, the complete spectrum, or how every object will look. [1]
CCT needs a companion
Two sources with the same nominal CCT can differ in chromaticity. IES TM-40 provides a method for CCT and distance from the Planckian locus, Duv. When investigating inconsistent white appearance, request chromaticity information rather than relying on the nominal CCT label alone. [2]
Color rendition is multidimensional
TM-30 evaluates overall fidelity and gamut together with hue-specific fidelity, chroma shifts and hue shifts. Its scope makes clear why one headline value cannot fully describe a source. Request the full report and compare the parts relevant to the objects in the space. [3]
A practical comparison session
Our recommended evaluation is to place candidate sources over the same representative materials, keep geometry and light level comparable, and record the intended effect. Include skin, finishes, merchandise or artwork relevant to the project. A preference observed in one scene does not establish universal superiority.
Tunable white is a capability
IES defines tunable white through spectral tuning that varies CCT. Specify the desired range and control behavior, then evaluate performance at more than one setting. A change in CCT alone is not evidence of a health outcome. Keep any biological claim tied to the particular research, exposure and population. [4]