Circadian lighting in open-plan daylit office spaces

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The British University in Dubai (BUID)
Humans tend to spend most of their time indoors, where they exposed to almost a constant amount a light that is inappropriate for their biological rhythms, specifically, the circadian rhythms. Light is the main trigger of these biological rhythms, which help keep it synchronized during the day and time, pointing out that these rhythms are sensitive to the shortwave length. Simultaneously, the insufficient amount of light can lead to circadian disruption, which affects human sleep, physiological functions, mood, and performance. Daylight count as a perfect light source that triggers circadian entrainment. The present research aims to deliver guidance on designing an open-plan daylit office space in terms of circadian lighting. Through computer simulation method, different architectural aspects were examined, including 4 different window-to-wall ratios, 3 orientations, 2 seasons, and 5 timing to obtain the vertical illuminance. Circadian Stimulus (CS) calculator used to obtain the CS value of all cases in order to check if it achieves the desired of 0.3 CS or more at the morning time (exposure for 1-hour). This research found that designing good circadian lighting in office shall always consider all variables; moderate window size can achieve the desired CS value using different supportive lighting sources during the day. On the other hand, high WWR fulfill the required CS during the morning and afternoon time while it exceeds the desired CS in the late afternoon time, which leads to a high risk of sleep disruptions and long-term disease. The research recommends considering that Dubai, as a location, has a harsh climate where windows orientation plays a key role in energy consumption and heat gain. In addition, circadian lighting has different parameters rather than the amount of light, including SPDs, duration of light exposure, and history of light exposure that should be included in the future studies.
circadian lighting, circadian rhythm, daylight, WWR, sleep cycle