Investigation of the photothermal–electrical characteristics of insulated and ventilated photovoltaic vacuum glazing systems

Contemporary research on building energy efficiency increasingly emphasizes passive environmental regulation and integrated energy generation. Photovoltaic vacuum glazing (PVVG), which provides solar control, electricity generation, and enhanced thermal insulation, has emerged as a promising solution for green building development. However, existing studies lack comprehensive annual evaluations of different PVVG configurations, resulting in insufficient understanding of their photothermal-electrical performance. This study establishes and experimentally validates a photothermal-electrical coupled simulation framework for PVVG systems in EnergyPlus. Based on the conduction transfer function (CTF) method, the framework incorporates coupled heat transfer, daylighting, photovoltaic (PV) power generation, and ventilated cavity models to accurately capture the dynamic thermal behavior of PVVG systems. Annual simulations are conducted for an office unit located in the hot summer and cold winter (HSCW) climate zone of China to compare the performance of insulated PVVG and ventilated PVVG under different orientations. In addition, a multi-objective optimization framework is developed to optimize PVVG design parameters. The seasonal thermal performance and the trade-offs among HVAC energy consumption, lighting demand, PV output, and daylighting performance are systematically quantified. PVVG significantly improves daylighting quality, increasing average useful daylight illuminance (UDI) by approximately 20%. With window-to-wall ratio (WWR) of 0.6 and cell coverage ratio (CCR) of 60%, PVVG achieves approximately 40% reduction in net energy use intensity (NEUI) compared with conventional double glazing (DG), while west-facing VENT-PVVG achieves the maximum reduction of 50.08%.