Analysis of the influence of CCT and Ra of common lighting sources on visual experience and energy efficiency

Indoor lighting significantly impacts visual comfort and energy efficiency in buildings. However, the random mixing of light sources (e.g., LEDs, CFLs, and thermal sources) often degrades lighting quality due to inconsistent Correlated Colour Temperature (CCT), Colour Rendering Index (Ra), and efficiency. In response, this study investigates artificial lighting in Guangxi University restaurants, a building type often overlooked in prior research. Over six common light sources in 10 buildings were analyzed using advanced tools, such as the CMS-2S spectrum analyzer and integrating sphere.

The results show that the type of light source significantly affects CCT, Ra, and energy efficiency, with random mixing exacerbating visual discomfort and energy waste. Furthermore, the study aligns with CIE S 026:2018, suggesting that LED sources, particularly those in the 3000–4000 K range, effectively support circadian regulation while maintaining visual comfort. It also complies with GB50034-2013 by meeting Ra and CCT standards for dining environments. Accordingly, this study highly recommends suitable methods for selecting light sources with appropriate CCT and high Ra to enhance visual comfort and reduce energy consumption, providing practical insights for future building design.