Performance prediction of a novel double-glazing PV curtain wall system combined with an air handling unit using exhaust cooling and heat recovery technology

Abstract

In solar buildings, the problems associated with indoor comfort and energy demand have garnered considerable attention, including overheating of BIPV systems, excessive cooling load, and cold-heat offset of HVAC systems. To address these problems, this study proposes a novel exhaust ventilation double-glazing PV curtain wall system (EVPV) combined with an air handling unit (AHU) based on waste heat recovery (HR). This hybrid system cools the PV curtain wall by utilizing exhaust air as a coolant. Additionally, the exhaust air is recycled to preheat the dew-point supply air and then precool the fresh air. Thus, solar energy is captured and converted into electricity and heat, while thermal energy is efficiently recovered. The system realizes superior electricity output, reduced cooling energy consumption, and remarkable reheat savings. For comprehensive performance prediction, a case study is conducted based on a restaurant building with a south-facing EVPV in Hefei, compared to one with a non-ventilation BIPV facade system without HR (NVPV). Based on the validated model, the results of a typical summer week operation indicate that the EVPV system can achieve (1) 7.87 kWh/day power generation and 7.14% PV efficiency, with 0.35% enhancement; (2) 7.68 kWh/day heat recovery from the PV double-glazing façade; (3) 8.41 kWh/day (62.31%) mitigation in reheat demand, 2.97 kWh/day (26.60%) reduction in room cooling load, and 39.94 kWh/day fresh air cooling capacity; (4) additional fan power of 16.29 kWh/day. In total, integrating the PV curtain wall with AHU using HR reduces overall energy consumption by 63.12 kWh/day (19.26%). Furthermore, the effects of air cavity depth and PV coverage ratio on the electrical and thermal behavior of EVPV are investigated. The results suggest that 0.08 m air cavity depth and a higher PV coverage ratio provide the building with a more promising energy-saving potential.