Improving Cabin Thermal Environment of Parked Vehicles under Direct Sunlight using a Daytime Radiative Cooling Cover

Abstract Car overheating after parking under the direct sunshine leads to not only more energy consumption of air conditions but also potential security issues, such as higher traffic accident rates and heatstroke of passengers. In this study, we propose a new type of car cover with the daytime radiative cooling effect (named as Cover R) to reduce interior temperature when parking outside. With utilizing a layer of innovative meta-material coating, this cover is capable of reflecting most sunlight and effectively emitting infrared radiation in the atmospheric window band (8 - 13μm). Experimental results have shown that under strong solar irradiation (>900 W/m2), the usage of Cover R decreases cabin air temperature by 31.1°C and 19.6°C compared that for a car without a cover and with a traditional cover, respectively, which efficiently avoids thermal shock to the passengers. A simulation model that reproduces experimental data well suggests that Cover R is able to improve personal comfort in hot days. Considering the initial energy cost of air conditions for high interior temperatures, the application of Cover R also saves gasoline and reduces carbon dioxide emission.