Models of sky radiance distribution and sky luminance distribution

Evaluating visual comfort and performance of three natural lighting systems for deep office buildings in highly luminous climates

100 Years of daylighting: A chronological review of daylight prediction and calculation methods

Experimental validation of ray tracing as a means of image-based visual discomfort prediction

A new advanced system of daylight prediction has been developed and presented by the authors for the highest utilization of natural daylight and appropriate saving of the electrical power consumed by the artificial lighting in daytime. Though the research works for this system and for the Mean Sky upon which it is based have already been published4)∼11), one of the most essential parts of the research work, that is, the framing of the Intermediate Sky and its detailed contents have been only presented in a brief paper in Japanese.8) The Intermediate Sky was framed mainly from the current materials which had already been gathered by the authors before starting of the research work, as the measurement to be required for the establishment of the Intermediate Sky should be carried out for a very long time. The procedure of framing the Intermediate Sky and its results are stated in this paper.

/pdf/luminance-distribution-of-intermediate-sky-39e2vnckbg.pdf

Luminance distribution of Intermediate Sky

The standard value of the horizontal illuminace from unobstructed sky has not been yet established in Japan for the calculations of the daylighting and PSALI, though it is the most essential and fundamental for the energy conservation in the field of lighting design. A great deal of data on the horizontal illuminance from unobstructed sky have been gathered for several years by the authors when they tried to measure the luminance distribution of the sky under various conditions; the data cover not only almost whole seasons through a year and various times within a day, but also different meteorological conditions. Based upon those data, a proposal on the values of the horizontal illuminance from unobstructed sky at the selected standard point (35°N, 135°E) has been made by the statistical analysis and research investigations, following the values at Nagoya, related to the percentage of the available hours to many kinds of the designed working duration, such as 9 a.m. to 5 p.m. This proposal has been considered very reasonable and useful for the calculations of daylighting and its applications, so it has been extended to be applied in all over Japan. Furthermore the method developed by this research work and the results stated in this paper have convinced the authors of their world-wide applicability.

Hiroshi Nakamura

Papers

Luminance distribution of Intermediate Sky

Study on the statistic estimation of the horizontal illuminance from unobstructed sky

正射影カメラによる輝度および輝度分布の測定 : その 1. 写真測光法と正射影カメラ・感光材料

Study on colour temperature of light from sky and its distribution in Japan