ENERGY EFFICIENT HUMAN CENTERED OFFICE LIGHTING: A CASE STUDY ON OPEN PLAN OFFICE WITH ABSENT ACCESS TO DAYLIGHT

1Our 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 standard-ized test for assessing how effectively lighting luminaires provide circadian-effective light to occu-pants. This study introduces a case study, optimum suspended height (OSH), measuring luminaire ef-ficiency in achieving a circadian stimulus criteri-on (CS: 0.3) and equivalent melanopic illuminance in lx (EML: 240) for 38 office workers, based on performance and comfort criteria. The paper out-lines OSH application to individual linear lumi-naire 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 sus-pended 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 Sleep iness Scale (KSS) test. The study aimed to under-stand 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.