Louvers are among the technical components considered for improving energy performance in buildings, and there has been increased interest in adapting the louver system. However, most previous studies have focused on their performance evaluation based on the width and angle of the slats, which allow for limited improvement in their efficiency. This study suggests a solar tracking-based movable louver (STML) system and examines the efficacy using a full-scale test bed. To do so, we developed a full-scale test bed and estimated the energy reduction and improvement of indoor uniformity of different types of STML systems, including vertical, horizontal, eggcrate, and hybrid. The main findings are as follows: (1) The proposed STML is a hybrid louver with four movable shafts due to its structural characteristics. The shading area is increased sequentially by controlling the length of the movable shaft adjacent to the sun through solar tracking. (2) Compared with conventional vertical and horizontal louvers, the STML can improve indoor uniformity by 5.0% and 13.9%, respectively. Unlike conventional louvers, the STML awnings are installed at the end of the daylighting window, reducing window view obstruction and creating a more pleasant indoor visual environment. (3) Compared with conventional louvers, the STML can reduce lighting and heating/cooling energy by 35.7–49.7%. These findings prove the effectiveness of the proposed system.

Some recent research in the area of light shelves has been focused on applying photovoltaic modules to light shelves to save building energy. However, due to the modules installed on the light shelf reflectors, most such light shelves have failed to improve both daylighting and generation efficiency. This study proposes a folding technology to improve light shelves’ daylighting and generation efficiency that uses photovoltaic modules and validates their performance using a testbed. The major obtained findings are as follows: (1) The proposed folding technology has a structure in which reflectors and photovoltaic modules fold alternately by modularizing the light shelf. The reflector and photovoltaic modules are controlled by adjusting the degree of folding. (2) Because light shelf angles for improving daylighting and generation differed depending on the application of the photovoltaic module, the optimal light shelf specifications differed. (3) Compared to previous light shelf technologies, the light shelf with folding technology and a photovoltaic module reduced energy use by 31.3% to 38.2%. This demonstrates the efficacy of the proposed system. (4) Applying a photovoltaic module can lower the indoor uniformity ratio, which means that the daylighting performance of the light shelf is degraded due to the reduction of the area occupied by the reflector.

In response to rising energy consumption in buildings, this study proposes a solar-tracking movable louver integrated with a photovoltaic (PV) module and evaluates its performance to verify its energy-saving potential. First, the louver system can be configured as either vertical or horizontal by modularizing and rotating its slats. A solar-tracking mechanism for single-axis louver control was also developed and proven effective. Second, for optimal energy-saving performance, the louver operation must respond to external environmental conditions. Its control should account for PV power generation and building energy demands for heating, cooling, and lighting to maintain comfortable indoor and outdoor environments. Third, the proposed louver system achieved a building energy reduction of 4.7–8.8% compared to conventional fixed technologies. However, in winter, the louver may obstruct solar gains, potentially diminishing its effectiveness in reducing energy consumption. While this study demonstrates the potential of the proposed louver technology for energy efficiency, it is limited by the scope of environmental and operational conditions considered in the performance evaluation. Further studies under diverse climatic scenarios are necessary to substantiate its broader applicability.

Due to the recent increase in building energy consumption, daylighting technologies such as light ducts are becoming increasingly important. However, conventional light ducts have limitations, such as light loss, uneven illumination, and spectral distortion as the transmission distance increases, restricting the development of a comfortable lighting environment. This study developed technical alternatives for transmission and diffusion parts to overcome these limitations and improve the daylighting performance of light ducts. The performance of these alternatives was verified through testbed experiments. The proposed light duct design minimized light loss through the arrangement of multiple relay lenses in series in the transmission part and improved indoor illuminance uniformity in the diffusion part using a double-reflection structure with upper and lower reflectors. Consequently, for a transmission distance of 20 m, the average illuminance increased by ~27.3% and the uniformity improved by an average of 47.8% compared to a conventional plastic optical fiber (POF)-based light duct. Even under intense summer sunlight conditions, a transmission distance of 30 m showed a high useful daylighting illuminance (UDI) ratio and considerbly reduced glare risk, indicating characteristics favorable for maintaining a comfortable visual environment. Furthermore, the proposed light duct exhibited a spectral distribution similar to that of outdoor sunlight, demonstrating the potential to ensure the continuous spectral characteristics of natural light transmitted indoors. Finally, it also exhibited the potential to maintain its higher daylighting performance even at a transmission distance of 30 m compared to conventional technology.