A new formula is proposed for evaluating discomfort glare from large glare sources with uniform luminance. The formula has four parameters: luminance of the glare source, size of the glare source, background luminance and position index. An experiment was conducted to investigate the effect of each parameter on the evaluation of discomfort glare. Twenty subjects evaluated discomfort glare from the model window. The new formula shows the relation between the degree of discomfort glare and the parameters. The formula is distinct from other formulas in that it has a simple form and the background luminance has little effect on the degree of discomfort glare. It is expected that discomfort glare from large glare sources with uniform luminance can be appraised using the formula.

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A new formula is proposed for evaluating discomfort glare from large glare sources with non-uniform luminance. Three types of experiments were conducted using a modal window divided into two parts. Each part of the window had different luminance. First, the luminance ratio was measured when the observers perceived the difference of luminance between the two parts. The result of the measurement shows that the difference of luminance can be perceived when the ratio is 1:1.24. In the second experiment, the window was divided into two parts of the same size, and the degree of discomfort glare from the window was investigated. In the third experiment, the same test was conducted, but the window was divided into two parts with different size. The degree of discomfort glare was calculated using two methods. One used the average luminance of the window as a parameter, and the other summed up the degrees of discomfort glare from both parts of the window. There were no significant differences between the two methods. Consequently, a formula that uses the average luminance is proposed for evaluating the discomfort glare from large sources with non-uniform luminance.

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White light-emitting diodes (LED) are well suited for museum lighting because they do not emit UV nor IR radiation, which damage artifacts. The color degradation of natural dyes and blue scale standards (JIS LO841) by white LED lamps are examined, and their performance for museum lighting is evaluated. Blue scale standard grades 1-6 and silk fabrics dyed with 22 types of natural dyes classified as mid to highly responsive in a CIE technical report (CIE157:2004), were exposed to five types of white LED lamps using different luminescence methods and color temperatures. Color differences were measured at each 15000 lx·hr (500 lx at fabric surface x 300 hr) interval ten times. Accumulated exposure totaled at 150000 lx·hr. The data on conventional white LED lamps and previously reported white fluorescence (W) and museum fluorescence (NU) lamps was evaluated. All the white LED lamps showed lower fading rates compared with a W lamp against Blue scale grade 1. The fading rate of natural dyes in total was equal between an NU lamp (3000 K) and a white LED lamp (2869 K). However, yellow natural dyes showed higher fading rates with the white LED lamp. This tendency is due to the high power characteristic of the LED lamp around 400-500 nm, which possibly contributes to the photo-fading action spectrum of the dyes. The most faded yellow dyes were Ukon (Curcuma longa L.) and Kihada (Phellodendron amurense Rupr.), and these are frequently used in historic artifacts such as kimono, wood-block prints, and scrolls. From a conservation point of view, we need to continue research on white LED lamps for use in museum lighting.

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A supplemental lighting system was installed at a large-scale seedling greenhouse (12.5 m×45 m), which supplies high quality and large quantity of seedlings to farmers through out the year. A test experiment of supplemental lighting for seedlings in this house was performed during the rainy season and winter-early spring to prepare for planting, when sunshine is sometimes insufficient. A mercury-free high pressure sodium lamp of 400W with a red to far-red photon flux (R/FR PF) ratio of 1.1 was developed and manufactured for this experiment. The average PPFD was 100μmol m^-2 s^-1. The experimental plants were lettuce, broccoli, and cabbage. In both rainy and winter-early spring experiments, we found that supplemental lighting was effective for seedling growth. Significant supplemental lighting effects in the rainy season were found for broccoli. Top fresh weights of both a 2h lit area before sunrise and after sunset were 30-60% greater than those of the non-lit area. A drop test of lettuce demonstrated that the remaining ratio of soil of both a 2h lit area before sunrise and after sunset were about 87%, and those of the non-lit areas were about 78%. Thus, good growth in roots was found. A significant supplemental lighting effect in winter-early spring was found in the lettuce experiment. Top fresh weights of both a 3h lit area before sunrise and after sunset were 165-200% greater than those of the non-lit area. In winter-early spring experiments, a clear difference between a 3h lit area before sunrise and after sunset was not found.

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