As LED luminaires continue to spread, spectral requirements for work place lighting regarding light colour and colour rendering are increasingly becoming an aspect of luminaires instead of light sources. In addition, the melanopic efficiency of light can be optimised thanks to modern LED light sources. For this purpose, white light from light sources of various spectral distributions is often mixed in a fashion that shapes the resulting light into the required temporal and spectral progression. (see chapter "Human Centric Lighting", section "Requirements for light control"). The spectral composition of the overall light emitted from the luminaire can already be measured very soundly using the Ulbricht sphere. Where various light sources – possibly with varying luminous intensity distributions among them – are operated within one luminaire, they should be measured and rated individually.
