IES TM-38-21

Lighting products emitting variable spectral power distributions (SPDs) are increasingly prevalent in the architectural lighting marketplace. While a few variable-spectrum products based on fluorescent lamp technology existed in the past, the capabilities of solidstate lighting (SSL) have enabled the development and widespread use of such products. Variable spectral output, however, is not explicitly accounted for in existing methods for characterizing photometric and electrical performance, which are focused on measurements taken at a single operating state, with the product supplied with the intended voltage and without control devices.