The performance of the Operable Building Integrated Photovoltaic (OBIPV) system applied to the building envelope to reduce the building energy consumption varies significantly depending on the operation method and influence of the surrounding environment. Therefore, optimization through performance monitoring is necessary to maximize power generation of the system. This study used temperature-corrected normalized efficiency (NE*) to evaluate the power generation performance of the operation methods and predict that of the OBIPV system based upon the measured data. It was confirmed that power generation performance decreased when the photovoltaic (PV) operation angle changed, the system remaining the same. A decrease in power generation performance due to partial shading from an overhang was also observed. As a result of the power generation prediction for two months using NE*, the error of the measured values was found to be less than 3%. In addition, with or without any partial shading of the OBIPV system, its performance degradation was predicted with an annual electricity generation decrease by 36 kWh/yr (6.5%). Therefore, NE* can be used as an indicator for evaluating the power generation performance of PV systems, and to predict generation performance considering partial shading.

Windows are essential in buildings; however, they have poor thermal performance, so extensive research has been conducted on improving their performance. In this study, we developed vacuum-glazed windows with excellent insulation via the in-vacuum method, which shortens the manufacturing time and vacuuming degree considerably. In addition, the configuration of the pillars, low-emissivity (low-e) coating, and frame from a thermal performance perspective was experimentally optimized. The results revealed that the optimal pillar placement spacing is 40 mm and that the low-e coating surface must be located inside the vacuum layer to maximize insulation performance. The vacuum-glazed window produced by the in-vacuum method was applied to an actual residential building to investigate its thermal performance, which was compared with that of a triple-glazed window. The results showed that the center-of-glazing heat flow of the vacuum-glazed window was approximately 0.8 W/m2K lower than that of the triple-glazed window. The difference between the average indoor and outdoor surface temperatures during the nighttime was found to be up to 35.1 °C for the vacuum-glazed window and 23.1 °C for the triple-glazed window. Therefore, the energy efficiency of the building can be greatly improved by applying vacuum windows manufactured via the in-vacuum method and optimized for the best thermal performance.