Energy-Efficient, Conservation-Safe Museum Lighting: A Blue-to-Yellow Ratio and Relative Damage Index LED Screening Framework

Museums face a conflict between energy-efficient gallery lighting and protecting light-sensitive collections from photochemical damage: increasing the luminous efficacy of white LEDs requires shifting spectral power toward the high-energy blue band, accelerating degradation of organic materials. Prior work treated these separately; this study links them via a shared spectral property, the blue-to-yellow emission balance. For four artifact classes (water colors on paper rag, oil colors on canvas, textile materials, and rag paper), luminous efficacy is calculated from spectral radiant power distributions, alongside a material-specific damage factor per unit of useful light derived from first-order kinetics. For each class and color temperature (CCT), this factor is benchmarked against a reference halogen source, yielding a relative photochemical damage index—a relative comparison rather than a computed permissible dose or exposure time—that flags spectra with lower hazard than current practice. Across the database, the blue-to-yellow spectral balance shifts faster than efficacy gains above 4000–5000 K, so higher CCTs carry a growing conservation cost; class-specific limits cut radiant power input in robust material galleries without compromising sensitive ones. Evaluated on nearly 2850 commercial LED spectra, the index gives lighting engineers and conservators a quantitative tool for selecting energy-efficient, conservation-safe LED products.