Improvement of light-shelf performance through the use of a diffusion sheet

Lee, Heangwoo; Seo, Janghoo; Kim, Suktae

doi:10.1016/j.buildenv.2018.07.040

Cited by 19 publications

(7 citation statements)

References 19 publications

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“…However, during mid-season, a flat light shelf with a reflector angle of 30 • introduced natural light into the room by reflection from the reflector rather than the ceiling, as shown in Figure 12. This angle was considered inappropriate because the occupants may experience an uncomfortable glare, which is consistent with the results of a study analyzing the discomfort glare of light shelves [24]. Therefore, the optimal angle of a flat light shelf during mid-season was set to 20 • and reflected in the performance evaluation results.…”

Section: Performance Evaluation Results and Discussionmentioning

confidence: 56%

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Preliminary Study on the Performance Evaluation of a Light Shelf Based on Reflector Curvature

2019

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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.

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Section: Performance Evaluation Results and Discussionmentioning

confidence: 56%

“…The performance evaluation method used in this study was based on the findings of relevant studies [19,24], and its details are as follows. 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.…”

Section: Performance Evaluation Methodsmentioning

confidence: 99%

Preliminary Study on the Performance Evaluation of a Light Shelf Based on Reflector Curvature

2019

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“…The main scientific method for the literature study used was a desk study (PC with an internet connection); no automation tools were used. • no translucent elements are used [22] experiment • light shelf using diffused reflection [23] experiment • study on a movable light shelf system [24] experiment • an awning system with a built-in light shelf [25] experiment full size testbed…”

Section: Methods and Eligibility Criteriamentioning

confidence: 99%

“…In the following years till the current time, the team of Prof. Heangwoo Lee published 11 papers considering different aspects of a light shelf and its performance. Those papers feature a light shelf using diffused reflection [22]; a movable light shelf system [23]; an awning system with a built-in light shelf [24]; the use of a diffusion sheet [25]; an evaluation of a light shelf based on energy consumption [26]; a light shelf with a solar module [27]; a light shelf based on reflector curvature [28] application of a prism sheet [29]; a movable light shelf with a rolling reflector [30]; and finally, in 2021, light shelves with photovoltaic modules [31].…”

Section: Light Shelfmentioning

confidence: 99%

An Evaluation of Useful Daylight Illuminance in an Office Room with a Light Shelf and Translucent Ceiling at 51° N

Brzezicki

2021

Buildings

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The present study investigates the issue of computer-aided daylight evaluation in an office room with a light shelf and dropped translucent ceiling. In this type of room, daylight is admitted from two sources: (i) a standard window in the wall and (ii) via a light shelf and clerestory window, which illuminate the plenum located above the working space. The light from the plenum is transmitted through the translucent ceiling into the office room. The present study is based on data obtained through a computer-aided daylight simulation by DeLuminæ (DL-Light, ver. 11.0.9, and DL-Instant, ver. 6.1.4) software using the Radiance engine and real weather data for Wroclaw, Poland, at 51st lat. N. An office room of 12 × 6 m with different shading and daylight distribution scenarios was simulated (Variants 1–5). Next, the useful daylight illuminance (UDI (%)) for the range of 300–3000 lx and daylight glare probability (DGP) were calculated. To further optimize the daylighting scenarios, an adaptive shading system was simulated, which was activated when the illuminance value dropped below 300 lx. In the final variant, Variant 6, mean UDI300–3000 values were recorded to be above 80% for 95% of the area of the work plane. This allows the conclusion that a light shelf and translucent ceiling guide daylight deep into the room, improving uniformity and reducing glare when the standard window is covered by an adaptive shading system.

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“…As shown in Table 1 , previous studies related to light shelves [ 5 , 6 , 7 , 8 , 12 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ] controlled the variables associated with light shelves or changed their shape to improve daylighting performance. Recent studies integrated various moving or operational technologies, including IT, and applied other elements to light shelves, such as awnings and PV modules.…”

Section: Introductionmentioning

confidence: 99%

A Study of Optimal Specifications for Light Shelves with Photovoltaic Modules to Improve Indoor Comfort and Save Building Energy

Lee

Zhao

Seo

2021

IJERPH

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Recent studies on light shelves found that building energy efficiency could be maximized by applying photovoltaic (PV) modules to light shelf reflectors. Although PV modules generate a substantial amount of heat and change the consumption of indoor heating and cooling energy, performance evaluations carried out thus far have not considered these factors. This study validated the effectiveness of PV module light shelves and determined optimal specifications while considering heating and cooling energy savings. A full-scale testbed was built to evaluate performance according to light shelf variables. The uniformity ratio was found to improve according to the light shelf angle value and decreased as the PV module installation area increased. It was determined that PV modules should be considered in the design of light shelves as their daylighting and concentration efficiency change according to their angles. PV modules installed on light shelves were also found to change the indoor cooling and heating environment; the degree of such change increased as the area of the PV module increased. Lastly, light shelf specifications for reducing building energy, including heating and cooling energy, were not found to apply to PV modules since PV modules on light shelf reflectors increase building energy consumption.

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Improvement of light-shelf performance through the use of a diffusion sheet

Cited by 19 publications

References 19 publications

Preliminary Study on the Performance Evaluation of a Light Shelf Based on Reflector Curvature

Preliminary Study on the Performance Evaluation of a Light Shelf Based on Reflector Curvature

An Evaluation of Useful Daylight Illuminance in an Office Room with a Light Shelf and Translucent Ceiling at 51° N

A Study of Optimal Specifications for Light Shelves with Photovoltaic Modules to Improve Indoor Comfort and Save Building Energy

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