Improvements in energy saving and thermal comfort for electric vehicles in summer through coupled electrochromic and radiative cooling smart windows

In hot climates, the large amount of cooling load in electric vehicle (EV) results in a lot of battery energy consumption, leading the decrease of driving range. With the widespread application of windows in EV, the electrochromic glass (EC) shows great prospect in lowering the cooling load. However, researches on the application of EC in EV lack the consideration of both passive cooling measures and passenger comfort, which limits the further application of EC. In this paper, we proposed an idea combining the novel techniques of both electrochromism and radiative cooling. Computational fluid dynamics (CFD) is modeled to simulate the application of electrochromic and radiative cooling coupled smart windows in hot parking conditions, exploring the improvement effect of the window on the thermal environment, comfort and energy saving of the EV. The results indicate that, under the intense sunlight with an outdoor temperature of 33 ℃, activating the air conditioning to maintain an average interior temperature of 26 ℃, the coupled windows reduced the cooling capacity of the air conditioning by 762 W compared to regular windows, which can further increase the range of EV. Meanwhile, compared to simple electrochromic fully colored glass, the integration of radiative cooling technology can lower the window surface temperature by up to 10.7 ℃. Moreover, compared to regular windows, the coupled windows lowered the standard effective temperature (SET*) for passengers by approximately 7 ℃, significantly improving comfort. These research findings are expected to provide guidance for optimizing window design and enhancing the performance of EV.