Seasonal Performance Comparison of Four Multi-function Double-layer CdTe Ventilated Windows in Different Climates

Windows play a critical role in building thermal performance and energy efficiency. An outer PV+PCM double-layer ventilated window (OPVPCM-VW) was developed in previous research, capable of space heating, ventilation cooling, and heat preservation. The PCM could lower PV temperature by storing solar heat around noon and release heat during night to improve thermal management. However, significant heat loss occurred through direct heat exchange between outer PV surface and environment, and most latent heat in PCM also dissipated to the ambient at night, limiting its effectiveness in cold climates. To address these limitations, internal PV+PCM double-layer ventilated window (IPVPCM-VW) is proposed and is compared with OPVPCM-VW, outer PV ventilated window (OPV-VW), and internal PV ventilated window (IPV-VW) under heating season and non-heating season in different region. Results show that although the electrical efficiency is slightly higher at 7.79% due to lower PV temperature in OPVPCM-VW, the PCM may not function in cold weather and the thermal efficiency is much lower than IPVPCM-VW’s 27.95% at 12.03%. Although the PCM are both functioned in Lhasa, the thermal efficiency of OPVPCM-VW at 23.10% is still lower than IPVPCM-VW at 26.16%. In non-heating season, IPVPCM-VW may cause higher cooling load in Hefei, but for Lhasa climate, it provides better heat preservation in cold nights while maintaining similar noon cooling performance to OPVPCM-VW. The content could provide guidance for the applicability and regional design of double-layer photovoltaic ventilated windows.