STUDY ON THE EFFECT OF DIMMERABLE LIGHTING FIXTURES POSITION ON SUBJECTIVE PERCEPTION

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  • 変動照明の位置が執務者の明るさ変化の知覚に及ぼす影響に関する研究
  • ヘンドウ ショウメイ ノ イチ ガ シツムシャ ノ アカルサ ヘンカ ノ チカク ニ オヨボス エイキョウ ニ カンスル ケンキュウ

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 Light control systems using motion sensor can efficiently save electricity in office settings, however, rapid change in illumination levels might cause unpleasantness to workers. Although there have been several researches that studied workers' perceptions of lighting fluctuation, the experiments were conducted with an uniform change of the rooms brightness.<br> In offices that use light control systems, there is a lot of fluctuation in lighting conditions due to illumination changes made by the system every time a worker leaves or comes back to his seat. Therefore, the purpose of this study is to better understand the effects of lighting fixture positioning on workers' perception of lighting fluctuations of office settings.<br> Two experiments were conducted. The first experiment was conducted in a room with white walls, beige ceiling and floor, and all windows closed so that there were no effects of daylight. The dimming of three different ceiling fixture positions was tested: at a 30°, 45° and 100° angle of the observers' eyesight line. The experiment had 20 participants that carried out 15 minutes tasks of writing and computer work combined. The room always had 2 participants at a time and they were asked whether they perceived any illumination change during the task. Illumination was dimed three times on a 15 minutes period, at different patterns. Initial illumination level was set to 750 lx, and final illumination was set to 530lx. Both variables were tested using 3 levels each: dimmerable lighting fixtures position at 30°, 45°, 100° angle from participants line sight and illumination change velocity at 3, 7 and 18 seconds, so that there were a total of 9 lighting fluctuation patterns. As a result, it was revealed that illumination changes happening in fixtures positioned at a 45° angle will be more easily perceived while illumination changes happening at 100° angle from the oververs eyesight line will be perceived the least. The experiment shown that the position of dimmerable lighting fixtures directly influences lighting perception.<br> The second experiment, tried to emulate, as close as possible, the lighting fluctuations of real office settings. The experiment was had three workstation : one for the participant and the other two to simulate other workers' desks. Fixtures were distanced 1.8m from themselves, according to guidelines of previous studies that advocate this distance as suitable for electricity saving. Participants performed the same task as the first experiment on a 30 minute interval. Illumination levels were fluctuated 8 times in different patterns. Initial illumination level was set to 750 lx, and final illumination was set to 565 lx in 2nd desk's pattern or 695 lx in 3rd desk's pattern. Fixtures with variable illumination were positioned on top of the 2nd and 3rd desks, and illumination were varied at 8 different velocity patterns: dimmering down at3, 8 and 16 seconds at either the 2nd or 3rd desk. Illumination levels would return to the previous level on a 3seconds interval, after each illumination change. As a result, fluctuating lighting fixture position influence the lighting the lighting perception of examinees, and the perception ratio of illumination change obtained from the second experiment was higher than the first experiment for almost all patterns. Details of these experiments are given in Chapter3.

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