Annual daylight quality of typical classrooms in sun-deficient areas

Abstract

This paper aims to disclose the daylight features in sun-deficient areas of China. For this purpose, the authors carried out field measurement with annual dynamic analysis on daylight in a university of Chongqing, a typical sun-deficient area. The annual daylight quality was evaluated in details from the angles of temporal and spatial variations. Specifically, the annual daylight data were condensed into 72 similar time periods according to the local academic calendar. The mean illuminance and spatial ratio of areas meeting the illuminance threshold were calculated in each period for two typical classrooms in the university. The results show that, in the south-facing classroom, the mean daylight illuminance on the desktop was below the threshold in winter and in early mornings (before 10:00) and late afternoons (after 16:00) of other seasons; in the north-facing classroom, the mean daylight illuminance on the desktop were below the threshold in virtually all 72 periods. In terms of space, less than 25% of the north-facing classroom and 55% in the south-facing classroom met the illuminance threshold. Compared with the traditional daylight evaluation methods, our strategy realizes a comprehensive and detailed evaluation of indoor daylight quality, shedding new light on reasonable lighting improvement.