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.

South Korea has announced a mandatory zero-energy building (ZEB) policy for apartments containing 30 or more households from 2023 to mitigate building energy issues and thus carbon emissions. Although formalized governance regulations and regimes are actively adopted in the domestic marketplace, the effectiveness of the building assessment method used in the ZEB certification system remains controversial. Therefore, this study examines changes in building energy consumption according to different usage schedules, focusing on internal heat gains (i.e., lighting and plug loads). To evaluate load diversity, we derive four representative profiles for lighting and plug loads based on the measurement data of 60 detached houses in South Korea. Finally, this study evaluates the changes in energy consumption according to the applied load profiles and their influence on the certification system. The findings from this study highlight the need to improve the existing domestic ZEB certification system by reflecting the effects of various domestic load profiles on energy consumption and building certification grades.