Abstract
The consumption of lighting energy in buildings continues to rise, and many studies are being conducted to address this problem. As part of such initiatives, research is being performed on light shelves, which are natural lighting systems. However, most prior studies focused on variables for operating flat reflectors and light shelves. This study aims to evaluate the performance of curved light shelves to prove their effectiveness and derive optimal specifications for them. The following conclusions were reached. The optimal light shelf angles for a flat light shelf were found to be 30°, 20°, and 20° for the summer, mid-season, and winter, respectively, and accordingly, a movable light shelf system would be suitable for all three seasons. The optimal light shelf angles for a movable curved light shelf with an arc angle of 60° were found to be 30°, 30°, and 10° for the summer, mid-season, and winter, respectively. The optimal light shelf angle and arc angle for a fixed-type curved light shelf were found to be 20° and 60°, respectively. A fixed-type curved light shelf designed according to these optimal specifications can reduce energy consumption by 3.6% in comparison to a movable flat light shelf. Consequently, the curved light shelf is considered an effective system, and additional studies analyzing various other factors should be carried out in the future.
Highlights
Concerns about global warming due to greenhouse gas (GHG) emissions are growing as the use of fossil fuels as energy sources continues to increase in the industrial, transportation, and building sectors [1]
We evaluated the performance of a flat light shelf and a curved light shelf to confirm the effectiveness of the curved light shelf used in this study
The optimal angle of a flat light shelf during mid-season was set to 20◦ and reflected in the performance evaluation results
Summary
Concerns about global warming due to greenhouse gas (GHG) emissions are growing as the use of fossil fuels as energy sources continues to increase in the industrial, transportation, and building sectors [1]. To address the issue of lighting energy consumption in buildings, many studies have been performed on light shelves, which are typical natural daylighting systems attached to windows to reflect external natural light into rooms via a reflector and the ceiling of the indoor space. Prior studies on the performance of light shelves have been limited in that they only address the use of flat light shelves, which introduce light into a room in just one direction, in a manner similar to that in which a mirror reflects light. Recent studies have addressed this limitation by evaluating the effects of various factors such as the width of the reflector [6] on the efficiency of flat light shelves
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