Energy Effıcıent Human Centered Offıce Lıghtıng: A Case Study on Open Plan Offıce wıth Absent Access to Daylıght

Abstract

Our daily behaviours and physiological functions are regulated by the brain’s central biological clock. Consistent exposure to bright days and dim nights is crucial for aligning these rhythms. Since we spend much time indoors, electrical lighting is often relied upon to sync our circadian rhythms. A challenge in promoting circadian entrainment through electrical lighting is the lack of a standardized test for assessing how effectively lighting luminaires provide circadian-effective light to occupants. This study introduces a case study, optimum suspended height (OSH), measuring luminaire efficiency in achieving a circadian stimulus criterion (CS: 0.3) and equivalent melanopic illuminance in lx (EML: 240) for 38 office workers, based on performance and comfort criteria. The paper outlines OSH application to individual linear luminaire type, including suspended-mounted fixtures. In this field study, tests were conducted to explore how indoor lighting affects occupants’ cognitive performance and visual perception. Linear suspended LED luminaires (LSL) were installed in an open-plan office at Istanbul Technical University (ITU), where office workers were exposed to different heights of lighting conditions. They took visual attention tests and assessed proofreading comfort, with alertness measured using the Karolinska Sleepiness Scale (KSS) test. The study aimed to understand the impact of visual fatigue on cognitive performance and perception with. These initial findings shed light on the relationship between office lighting changes and occupants’ cognitive performance and visual perception.