The effects of the correlated colour temperature of light on thermal sensation in the built environment: A systematic review and meta-analysis

Recently, the effect of the correlated colour temperature (CCT) of light on human thermal sensation has drawn much attention from the built environment area because of its potential application to change indoor comfortable temperature set points and save energy in buildings. Many studies have been conducted on this topic, and the results have proved inconsistent, making them difficult to use in actual practice. To further understand the validity and application range of the effect, it is urgent to research and reflect on a heterogenous selection of relevant studies. Thus, this paper aims to conduct a systematic review of existing studies, investigate the reasons for heterogeneity and explore the effect of moderators on experimental results. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method was used for the systematic review, while the method of Meta-analysis was utilised to investigate the reasons for heterogeneity and the effect of moderators. The meta-analysis found that a higher CCT can lead to a cooler thermal sensation, while environmental factors, such as the background thermal environment, temperature and exposure duration, moderate the effect's magnitude. The results of the meta-analysis suggest that in the thermally neutral environment, the effect of CCT on thermal sensation is most significant. Meanwhile, the magnitude of the effect diminishes with the duration of exposure. For the first time, this study explains the reasons for the heterogeneity of existing studies and reveals the influence of moderators on the thermal effect of CCT.