Comparative analysis of thermal efficiency for thermochromic Trombe wall in heating and cooling seasons

To reduce the cooling load of the room with Trombe wall during summer and improve its practicality, a novel thermochromic glass Trombe wall (TCG-TW) was proposed. The potential of TCG-TW for passive thermal regulation under winter and summer climatic conditions and quantitatively compared with the classic Trombe wall (C-TW). A transient heat transfer model was developed for TCG-TW to simulate the coupled effects of dynamic optical switching, heat conduction, and natural convection under solar radiation conditions of 200–800 W/m2 and ambient temperature ranging from −5 to 40 °C. The results reveal that TCG-TW can effectively reduces excessive heat gain during summer, and the negative effect of TCG-TW on the thermal efficiency in heating mode is small and can be accepted. TCG-TW can successfully change its color and significantly block the heat from solar radiation on most of days in summer and remain clear state in heating mode when the solar radiation intensity is lower than 400 W/m2 and the environment temperature is below 25 ℃. The dynamic modulation of solar transmittance by the thermochromic glass enables improved thermal comfort and seasonal adaptability without relying on active control strategies. TCG-TW effectively suppresses excessive solar heat gain during summer while having only a negligible influence on winter thermal performance. The absorber plate temperature of the TCG-TW is on average 23 % lower than that of the CTW in ventilating mode. The average differences of thermal efficiency for C-TW and TCG-TW is 6.5 % during winter. TCG-TW contributes to reducing ventilation energy demand during transitional seasons and enables the maintenance of indoor thermal comfort in winter under zero operational energy consumption condition. TCG-TW enhances the energy efficiency and climate responsiveness of passive solar heating systems in building applications.