The physiological and psychological impact of artificial windows on office workers during working phases: Cognitive performance and productivity

• Artificial windows are evaluated by referring real windows and no windows. • Artificial windows achieved the highest lighting comfort and acceptability. • Artificial windows matched or surpassed real windows in attention, memory, and creativity. • Artificial windows effectively enhance attention, creativity, and comfort in windowless offices. In modern urban environments, limited space and the drive for building efficiency have led to the increasing prevalence of windowless offices. Because lighting is essential for mood, alertness, cognitive performance, health, and productivity, the lack of natural daylight and outdoor views can adversely affect well-being and work outcomes. Consequently, artificial windows (AW), designed to replicate natural light and external views, have been proposed. This study compared real windows (RW), AW, and no windows (NW) to investigate their effects on cognitive performance and productivity among office workers during working phases. A controlled experiment was conducted, combining heart rate variability (HRV) data and cognitive tests. In addition, questionnaires were used to evaluate participants′ subjective perceptions of the thermal and lighting environments. The results showed that AW led to better attention, short-term memory, and creativity. In particular, the time for attention tests was about 14.4 % shorter than under NW, and the time for short-term memory tests was reduced by 6.7 %. Focus, measured by the HRV (nLF/nHF) ratio, increased by approximately 22.2 %, while subjective work efficiency demonstrated an even more substantial increase. Moreover, AW provided superior thermal and lighting perceptions compared to NW and even outperformed RW in lighting comfort and acceptability. Overall, these findings indicate that AW holds considerable potential for improving attention, productivity, and environmental comfort during working phases, offering an effective alternative for windowless offices.