User acceptance studies for LED office lighting: Preference, naturalness and colourfulness

Abstract

Two mock-up office rooms, one with a spectrally tuneable LED lighting system and the other with a fluorescent lamp (FL) lighting system were built for user acceptance studies for office lighting. One room was illuminated with six LED luminaires and the other with six FL luminaires. Each LED luminaire has 480 LEDs (20 different LED types and 24 of each type). Each FL luminaire has eight fluorescent lamps, four with a correlated colour temperature of 4000 K and four of 6500 K. User acceptance studies in the office environments were conducted with 40 observers, each observer having 16 sessions (six LED spectral power distributions (SPDs) þ two FL SPDs and two illuminances (500 lux and 300 lux)). The observers performed office-related tasks while being totally immersed in one of these lighting conditions. The objective of this study was to verify previous results obtained in small-scale booth experiments and to further study peoples' preferences for LED office lighting. The small-scale experiments showed that LEDs with a higher value of reference-based colour metrics (such as colour quality scale (CQS) colour preference scale) and with a higher value of area-based or volume-based metrics (such as CQS gamut area scale or gamut area index) were preferred by the observers. The office room study of the present work validated the findings of the earlier experiments but now in an office lighting environment. Furthermore, the observers preferred 4000 K to 6500 K at a light level of 500 lux and the light level of 500 lux over 300 lux. It was also found that the simplest LED SPD with three peaks has similar colour quality characteristics to complex LED SPDs with several peaks.

Preference index for Japanese complexion under illuminations

“…However, a method based on preferred color appearance has no yet been recommended by CIE or JIS. Recently, color preference index, especially for LED lamps, [3][4][5] has been discussed by CIE technical committee TC1-91 and some of related indices have been proposed as well. [6][7][8][9][10] Familiar objects have been selected as test-color samples for the method based on preferred color appearance.…”

Effect of Window Glazing on Colour Quality of Transmitted Daylight

“…Moreover, from the studies [31][32][33][34], it was clear that R9 is not an indicator of subjective preference. However, the chroma and colourfulness values of object colours calculated using CAM02-UCS have a great influence on the subjective preferences, especially for the naturalness and colourfulness (subjective measure).…”

Assessment of methods of marking LED sources with the power of equivalent light bulb

“…The signal then goes to the luxmeter measuring head (10). During laboratory measurements, as a result of the light emitted, this measuring head sends the electrical signal to the luxmeter control unit (11), which is connected to the computer (13) by means of an external power supply (12). The connection of both the meters (luxmeter L100 and power analyzer Norma 4000) to the PC type computer has been effected using the RS-232C serial transmission link.…”

“…Currently, a strong demand has been observed in the field of LED sources which are commonly accepted as excellent replacements of classic light bulbs. Simultaneously with the development of LED sources, considerable interest has been noticeable also in the literature where studies of lighting and electrical parameters of LEDs have been presented, and LED-based applications have been considered [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. From the point of view of the average consumer, the fact of strong marketing conducted by the manufacturers of LEDs, which focuses only on the advantages of these types of light sources, is also notable.…”