A "transparent radiative cooling film" technology that dissipates heat directly to the outside without consuming electricity has been developed to reduce vehicle overheating during summer. The technology was validated through real-vehicle experiments conducted under diverse conditions—including different countries, seasons, and both parking and driving scenarios—and demonstrated the ability to lower cabin temperatures by up to 6.1°C and reduce cooling energy consumption by more than 20%.
Seoul National University College of Engineering announced that a research team led by Prof. Seung Hwan Ko (Department of Mechanical Engineering, SNU), in collaboration with Prof. Gang Chen at MIT and research teams from Hyundai Motor Company and Kia (Materials Research & Engineering Center and Thermal Energy Total Development Group), has designed and fabricated a large-area Scalable Transparent Radiative Cooling (STRC) film applicable to vehicle windows. Through real-vehicle evaluations conducted under various climatic and driving conditions, the team demonstrated both energy-saving and carbon reduction effects.
This research was supported by the Global Leader Research Center funded by the Ministry of Science and ICT and the National Research Foundation of Korea, and was published online on February 4 in the internationally renowned journal Energy & Environmental Science.
Vehicles exposed to solar radiation in summer experience rapid increases in cabin temperature, resulting in substantial cooling energy consumption. Conventional automotive Low-E coatings* and tinting films** can partially block incoming solar radiation but fail to effectively dissipate heat already accumulated inside the vehicle, thereby limiting their cooling performance.
* Low-E (Low-emissivity) coating: Also known as "low-radiation coating," a technology that minimizes heat transfer by depositing a thin metallic layer (e.g., silver, Ag) on the glass surface.
** Tinting film: Commonly referred to as "window tint," a film applied to vehicle glass to reflect or absorb solar energy.
Radiative cooling technology, which has attracted attention as an alternative, simultaneously blocks incoming solar energy and emits internal heat to the outside, enabling passive cooling without electricity. However, most previously developed radiative cooling materials are opaque, making them unsuitable for application to vehicle windows, which are the primary entry points for heat.
To overcome this limitation, the research team developed a large-area transparent radiative cooling film with a multilayer structure that maintains over 70% visible light transmittance, reflects near-infrared solar radiation, and emits heat from the vehicle interior in the mid-infrared range. This film suppresses temperature rise inside the vehicle without consuming electrical energy and reduces the time required to reach thermal comfort, thereby minimizing energy consumption in electric vehicles.
Real-vehicle experiments conducted across different climatic regions—including Korea, the United States, and Pakistan—and under varying conditions such as summer and winter, as well as parking and driving scenarios, confirmed that vehicles equipped with the STRC film consistently maintained lower cabin temperatures under all conditions.
Notably, the cooling energy savings achieved in summer significantly outweighed any increase in heating demand during winter. In addition, simulations based on real vehicle data showed that the time required to reach a comfortable cabin condition after activating the air conditioner was reduced by 17 minutes. According to the research team's analysis, applying this technology to all passenger vehicles in the United States could reduce carbon dioxide emissions by approximately 25.4 million tons annually—equivalent to removing about 5 million vehicles from the road.
First author Min Jae Lee (Seoul National University/Hyundai Motor Company–Kia) stated, "This study is particularly meaningful in that it goes beyond laboratory-scale performance and validates the technology using real vehicles under diverse national, seasonal, and operational conditions."
Prof. Seung Hwan Ko added, "This is the first study to experimentally demonstrate that transparent radiative cooling technology can be effectively applied in real vehicle environments."
□ Introduction to the SNU College of Engineering
Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of 'fostering leaders for global industry and society.' In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.
