Optimization of photovoltaic shading angles for net energy and indoor daylighting: a case study in Beijing

Abstract

Photovoltaic shading devices (PVSDs) have significant potential to reduce building energy consumption and improve indoor daylighting. However, most previous studies have investigated PVSD performance at the single-building scale, while room-specific design and the effects of surrounding-building shading remain underexplored. To address these gaps, this study developed a room-scale multi-objective optimization framework for a typical residential unit in Beijing, explicitly considering surrounding-building shading while optimizing energy and daylighting performance. The results show that optimal PVSD control is jointly influenced by room function, façade orientation, and surrounding-building shading, leading to clear room-specific and seasonal differences in optimal tilt angles. Further analysis shows that surrounding-building shading has a substantially greater impact on indoor visual performance than on building energy performance. Compared with the isolated-building scenario, surrounding-building shading increased sGA by up to 22.50% and decreased UDI by up to 20.12%, while increasing NEC by up to 5.17%, highlighting the importance of accounting for surrounding-building shading in PVSD optimization. With surrounding-building shading included, seasonal dynamic control further improved energy performance compared with annual dynamic control, reducing annual NEC by 4.44%. These case-specific findings provide a useful reference for room-scale PVSD design and dynamic control in similar high-density residential contexts. However, the study was based on a single typical residential unit in Beijing, and the adopted envelope U-values represent conventional residential thermal performance. Therefore, the applicability of the findings should be further examined under different façade orientations, floor levels, surrounding-building conditions, and envelope thermal-performance levels before broader generalization.