Maintenance factors in installation of tunnel lighting have been considerd in terms of traffic volume and tunnel length based on results from investigations into the use of tunnels. Ventilation conditions in tunnels are drastically improved by reinforcing exhaust gas regulations for cars, and dirt on luminaire is also remarkably reduced. Further, the life times of light sources are advancing. Therefore, we studied lumen maintenance factor, survival factor and partial maintenance factor by using dirty luminaire to take maintenance factor into consideration and these suggested a new method of establishing maintenance factor.
The purpose of this study is to show the effect of the density of lattice and the lighting environment on the evaluation of comfort at Machiya-cafes. We conducted a subjective evaluation by using a scale model of a Machiya-cafe with which the density of lattice and the lighting environment could be changed. In this experiment, subjects evaluated four evaluation factors: "Recognizable from the outside," "Signline level from the outside," "Suitability of the lighting environment," and "Comfort at Machiya-cafes," with six steps of the categorical scale. Subjects were 15 female university students. As a result of the evaluation, it was shown that the evaluation of "Recognizable from the outside" was higher, as the density of lattice was bigger. For the evaluation of "Signline level from the outside" was higher, as the density of the lattice was smaller. For the evaluation of "Suitability of the lighting environment," subjects preferred a low color temperature to a high color temperature in the nighttime. For the evaluation of "Comfort at Machiya-cafes," it was shown that a 20 -40% density of lattice with a low color temperature was evaluated highest. Therefore, it was shown that a strong correlation was observed between the density of the lattice and the evaluation and that subjects preferred a low color temperature to a high color temperature in the nighttime.
The use of luminaires with LED array is increasing. The luminance distribution varies by the number and interval of the LED devices, and the diffusers used in the luminaires. Discomfort glare is a problem for practical lighting design. When using the exiting method with discomfort glare ratings, the luminance distribution is shown to be uniform. However, whether the typical luminance distribution of LED luminaires can be considered uniform is a problem. In this paper, the result of an experiment under a certain condition of the background luminance and the position and size of luminaire, is shown in which discomfort glare ratings of LED luminaires, such as offense to the eyes, glare, and the discomfort of the glare, were obtained for several luminance distributions of LED luminaires. The relationships between the transparency of the filter for visual field and the discomfort glare ratings are shown. An equivalent luminance coefficient is defined as the ratio of the uniform luminance to the average luminance of the luminaire, both which gives the same discomfort glare ratings. The equivalent luminance coefficients are shown for each luminance distribution. The UGR value, corrected by the equivalent luminance coefficient, is useful for estimating the discomfort glare rating.
Organic EL (OLED) has been attracting attention as a next-generation lighting fixture that can achieve high energy efficiency. One of the advantages of OLED is that there is a lot of flexibility in terms of choosing which organic materials to use, which in turm creates various spectral distributions of light. For this purpose, it is important to evaluate the performances of color perception under OLEDs. In this research, we measured the color discrimination performance under a prototype OLED light and compared the results with those derived under fluorescent light and under a commercially available LED lamp. Some observers had more difficulty discriminating color under OLED compared with under D65 fluorescent light. Although the spectral distributions of the light sources were different, the performances did not indicate any statistically significant hue dependences.
This study investigated the effect of color illumination on human behavior, especially cognitive performance. A series of experiments examined the hypothesis proposed by Mehta and Zhu (2009). The hypothesis was that red induced "avoidance motivation" enhancing the performance of tasks which needed attention to details, while blue induced "approach motivation" improving the performance in creative tasks. We employed some of the experimental tasks used in their study as well as our original ones. The task performances under red and blue illumination were compared. The results showed that memory performance increased in red condition compared to blue condition. However, the performance in the other cognitive tasks did not show any difference between the two illumination conditions, although subjective evaluation of the illumination colors showed different profiles between them. These results indicate that red illumination possibly enhances attention and/or focusing properties than blue, but that blue does not necessarily enhance performance in creative tasks than red.