Effect of Lighting Illuminance and Color Temperature on Mental Workload in Office Setting

The mental workload of subjects was tested in different lighting conditions, with color temperature ranging from 3000K to 6500K and illuminance 300 lx to 1000 lx. We used both psychological and physiological responses for evaluation. The former was based on the NASA-TLX scores, and the latter was based on EEG P3b analysis of event-related potentials with the “oddball” paradigm experimental task. Results show that the P3b amplitudes are significantly affected by color temperature (P = 0.009) and illuminance (P = 0.038) levels. Office environment with 3000K color temperature and 750 lx illumination, which exerts the lowest mental workload, is the most suitable for working. However, the interaction between color temperature and illuminance in affecting the mental workload of participants is not clear. This work provides more appropriate lighting choices with color temperature and illuminance in order to reduce people’s mental workload in office setting.