SNU researchers develop electricity-free radiative cooling technology

Beating vehicle overheating under sunlight with a single “transparent radiative cooling film” / Up to 20% reduction in summer cooling load, maximizing electric vehicle efficiency

Seoul National University College of Engineering

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Figure 1. Conceptual illustration of vehicle application of large-area transparent radiative cooling film
This figure presents the concept of applying a four-layer STRC film to vehicle glass, which simultaneously achieves visible light transmission, near-infrared reflection, and mid-infrared emission.

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Credit: © Energy & Environmental Science, originally published in Energy & Environmental Science

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.

  

Figure 2. Analysis of CO₂ emission reduction in the United States based on vehicle evaluations in summer and winter

Based on evaluations of cabin temperature and heating/cooling energy consumption under parking conditions in both summer and winter, this analysis estimates the potential reduction in carbon dioxide emissions if the STRC technology were applied to vehicles across the United States.

Credit

© Energy & Environmental Science, originally published in Energy & Environmental Science

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Journal

Energy & Environmental Science

DOI

10.1039/D5EE06609C 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Towards decarbonization in transportation: scalable transparent radiative cooling for enhanced vehicle energy efficiency

COI Statement

A KR patent (application no. 1020230179087) related to this work has been filed. M. J. L., T. H. K., W. S. K., J. H. S., H. J. L., and S. H. K. are inventors of this filed patent.

 

Examining the impact of sanctioned elites on authoritarian realignment

A researcher investigates how economic elites responded to deterioration of democratic checks and balances in the Japanese legislature (1936–1942)

Waseda University

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Research shows that international economic and political shocks can weaken democratic checks and balances from within.

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Credit: Associate Professor Makoto Fukumoto from Waseda University, Japan

In recent years, many observers have noted parallels between the current international environment and the 1930s, including rising geopolitical tensions, political polarization, trade conflicts, and regional wars. This raised a broader question: How do changes in the international environment reshape domestic political landscapes? From an academic perspective, much of the existing research on democratic backsliding focuses on voters or on political actors who mobilize and manipulate voters. While these perspectives are important, the incentives and behavior of economic and political elites are often examined less systematically. Therefore, it is crucial to understand how changes in the global economic and political environment influence the choices made by these actors.

Furthermore, economic sanctions and trade restrictions are frequently used as tools of international policy, yet relatively little is known about how such measures affect domestic political coalitions within the targeted or affected countries.

In a new study, Associate Professor Makoto Fukumoto from the Faculty of Political Science and Economics, Waseda University, Japan, aimed to provide a clearer understanding of how international economic pressure can reshape domestic political alignments by examining historical cases, specifically focusing on the Japanese legislature from 1936 to 1942.

This study examines how economic interests shaped the behavior of political elites in prewar Japan as military influence expanded. Focusing on legislators with ties to different industries, it analyzes key parliamentary moments when they either resisted or supported the military’s suppression of dissent. The study highlights two major economic shocks: U.S. sanctions (1940–41), which harmed export-dependent sectors, and the expansion of military procurement, which benefited firms supplying the armed forces. Using statistical analysis, it finds a clear contrast: legislators linked to sanction-hit industries became significantly more supportive of military-backed policies, while those connected to procurement sectors showed no similar shift and, in some cases, became more independent. These findings challenge the common view that economic beneficiaries of war are the strongest supporters of authoritarian rule, showing instead that economic vulnerability can drive elites to align with authoritarian power.These insightful findings were published online in the journal American Political Science Review on March 2, 2026.

This research helps us better understand how democracies can weaken during periods of international tension and economic disruption. In particular, it highlights the role of economic and political elites, such as business leaders and legislators, in shaping whether democratic institutions remain resilient or gradually erode. Public debate often focuses on voters when discussing democratic backsliding. However, political transitions are also strongly influenced by the decisions made by elites who control economic resources, political organizations, and legislative institutions.

The study shows that when internationally connected economic sectors come under pressure—for example, through trade conflicts or sanctions—elites associated with those sectors may lose political influence. This can shift the balance of power toward actors who support more authoritarian policies. The findings therefore suggest that international economic measures, such as sanctions or trade restrictions, can have unintended domestic political consequences. Policies designed to pressure governments may also reshape internal political coalitions in ways that affect democratic institutions.

The present work has two major real-life applications. One important application concerns the use of economic sanctions and trade restrictions as tools of international policy. Governments frequently rely on sanctions to pressure other states, but the domestic political effects of these measures are often complex. The research suggests that sanctions and trade conflicts can unintentionally weaken internationally connected economic actors who might otherwise favor moderation and cooperation. This insight can help policymakers better anticipate how economic pressure may reshape political coalitions within targeted countries.

A second application relates to understanding elite behavior in authoritarian or hybrid political systems. Political outcomes in such systems often depend on how business leaders, legislators, and other influential actors respond to shifts in power. The study shows that when certain groups of elites become economically vulnerable, they may be more likely to accommodate authoritarian initiatives rather than resist them. This perspective can help analysts and policymakers better interpret political developments in countries where formal democratic institutions are under strain.

Overall, by examining historical evidence from the 1930s, the research offers insights that remain relevant today. It helps policymakers, analysts, and the public better understand how global economic tensions can influence domestic political stability and democratic governance, concludes the author.

For readers interested in the full set of figures, tables, and supplementary analyses, an earlier working paper version of this study is publicly available through the Waseda University Institute of Political Economy (WINPEC) Working Paper Series. While the final and authoritative version is published in the American Political Science Review, the working paper provides more accessible access to supplementary materials.

The working paper can be accessed here: https://www.waseda.jp/fpse/winpec/assets/uploads/2025/12/E2526.pdf

 

Reference
Author: Makoto Fukumoto

DOI: https://doi.org/10.1017/S0003055426101440

Affiliations: Faculty of Political Science and Economics, Waseda University

 

About Waseda University
Located in the heart of Tokyo, Waseda University is a leading private research university that has long been dedicated to academic excellence, innovative research, and civic engagement at both the local and global levels since 1882. The University has produced many changemakers in its history, including eight prime ministers and many leaders in business, science and technology, literature, sports, and film. Waseda has strong collaborations with overseas research institutions and is committed to advancing cutting-edge research and developing leaders who can contribute to the resolution of complex, global social issues. The University has set a target of achieving a zero-carbon campus by 2032, in line with the Sustainable Development Goals (SDGs) adopted by the United Nations in 2015. 

To learn more about Waseda University, visit https://www.waseda.jp/top/en  

 

About Associate Professor Makoto Fukumoto from Waseda University, Japan
Makoto Fukumoto is an Associate Professor at the Faculty of Political Science and Economics, Waseda University, Japan. He received an MSc in International Political Economy from the London School of Economics and Political Science in 2015, and a Ph.D. in Political Science from the University of California, Berkeley, in 2021. His research interests include political economy, political behavior, public policy, political geography, interest groups, pork-barrel politics, comparative political economy, urban politics, and public economics. He is a member of the Urban Economics Association, the American Political Science Association, and the Midwest Political Science Association.

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Journal

American Political Science Review

DOI

10.1017/S0003055426101440 

Method of Research

Case study

Subject of Research

Not applicable

Article Title

The Cornered Mouse: Sanctioned Elites and Authoritarian Realignment in the Japanese Legislature, 1936–1942

 

Ceremony marks construction milestone

DOE/Sandia National Laboratories

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Time lapse video shows construction progress on the Power Sources Capability building at Sandia National Laboratories.

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Credit: Video Courtesy of Sandia National Laboratories

ALBUQUERQUE, N.M. — Workers marked a major milestone on one of Sandia National Laboratories’ largest construction projects of the past decade with an April 14 ceremony celebrating the installation of the final beam on the Power Sources Capability building.

“We want to celebrate all the work that’s been done to date and reaffirm our commitment to delivering on the remaining work,” said Perry D’Antonio, a senior manager overseeing the project’s technical requirements.

Construction on the new facility began in August 2025, and the beam ceremony signified completion of the building’s steel structure.

“Construction is advancing ahead of schedule,” said Savannah Torres, the project manager overseeing execution. “We’ve met or exceeded all major milestones to date and intend to keep up the pace.”

Construction on the 136,000-square-foot facility in Technical Area II is on track for completion in 2028. Equipment and employees will transition into the Power Sources Capability building afterward. The project’s final cost is projected at $400 million. The new building will be south of the Battery Test Facility.

Mission critical

Power sources are critical to the nuclear deterrence mission.

“Every system needs a power source,” said Sara Pecak, a senior manager. “Our program spans four technology areas, including thermal batteries.”

For example, once a weapon system separates from an aircraft, power sources provide main mission power through detonation. Sandia’s responsibilities for power sources include research and development, design, production and surveillance.

“Making power sources requires some unique capabilities, such as dehumidified rooms, also called dry rooms,” Pecak said. “The stringent requirements and limited supplier base require the nation to maintain this capability internally.”

Aging infrastructure

The new building will replace an aging facility that does not have the infrastructure or capacity for all the work to happen under one roof. Instead, four separate buildings are currently needed to complete all the power sources work.

“One of the things we asked for in the new building is the ability for people to walk past one another,” Pecak said. “That’s part of the design concept. We want to create an environment where people can have conversations even if they’re not working on the same projects.”

Conceptual design work began in 2019.

“We did a lot of value engineering from the original conceptual design,” D’Antonio said. Value engineering identifies alternative approaches that preserve mission function while reducing cost, improving constructability and strengthening overall project value throughout design and construction.

Future-focused

“We’ve created what we think is one of the most efficient design concepts to meet the mission both today and for the next 50 years,” D’Antonio said. “We want to build in agility for changing missions over the building’s lifespan.”

There has been strong collaboration between Sandia and key partners, including the National Nuclear Security Administration, general contractor Hensel Phelps and architecture and engineering firm SmithGroup.

“The expertise of the architecture and engineering firm and the general contractor, combined with support from the cross-functional Sandia and NNSA team, has been instrumental in positioning the project for successful execution,” Torres said. “This project not only delivers the facility needed to advance the power sources mission but also establishes a strong framework for future projects within Sandia’s multibillion-dollar line-item portfolio.”

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The new Power Sources Capability building at Sandia National Laboratories will replace an aging, outdated facility and was designed to adapt to changing missions over the next 50 years.

Construction on the new Power Sources Capability building at Sandia National Laboratories is expected to be completed in 2028.

A technologist at Sandia National Laboratories works on a thin film thermal battery as his colleague performs quality assurance checks for the Power Sources Capabilities team.

Credit

Photo by Craig Fritz/Sandia National Laboratories

Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.

 

Shrink, remove and modify: IPK team ‘trims’ wheat chromosomes

Leibniz Institute of Plant Genetics and Crop Plant Research

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While the targeted manipulation of entire chromosomes is well established in model organisms such as Arabidopsis thaliana, it has posed a significant challenge in crops with large genomes, such as wheat. The IPK research team has now set out to determine whether highly repetitive DNA sequences known as satellite DNA are suitable targets for the CRISPR gene-editing system. The idea was that cutting many of these identical sequences simultaneously could affect the entire chromosome. The team introduced CRISPR components into the plants using a virus-based system. This approach bypasses lengthy traditional transformation processes and enables highly efficient chromosomal modifications.

“In our study, we were actually able to demonstrate for the first time that chromosomes can be efficiently reduced in size by making targeted cuts in satellite DNA,” says Dr. Jianyong Chen, the study’s first author. This is a significant breakthrough, as such changes had previously only occurred by chance. You can think of it like a rope. If you cut a rope in several places at once, it becomes unstable and eventually snaps. The same thing happens to chromosomes when many cuts are made simultaneously.

In some cases, the method resulted in the loss of entire chromosomes. “If too many breaks occur, the cell can no longer repair the chromosome efficiently - it is lost entirely,” explains Prof. Dr. Andreas Houben, head of the IPK’s research group ‘Chromosome Structure and Function’.

Faulty repair processes can also create new forms of chromosomes, called isochromosomes. “These changes can generate new genetic variants, opening pathways for breeding resistant wheat and other crops," explains Prof. Dr. Andreas Houben. This innovation potential should inspire optimism about future crop improvements.

The study shows that plant genomes can be modified with unprecedented precision. Notably, satellite DNA, once considered ‘genetic ballast’, is now an effective target for modern breeding tools. “This approach enables efficient manipulation of chromosomes, paving the way for transferring valuable traits from wild relatives into cultivated wheat,” say the IPK scientists, encouraging a sense of empowerment in future crop development. 

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Journal

Plant Communications

DOI

10.1016/j.xplc.2026.101833 

Article Title

Satellite DNA-targeted CRISPR/Cas9-mediated editing enables chromosome truncation and elimination in wheat

 

Satellite data reveal hidden crop planting timelines

Journal of Remote Sensing

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Harmonized Landsat Sentinel-2 (HLS) tiles selected in agricultural areas across 13 US states, including PhenoCam monitoring sites.

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Credit: Journal of Remote Sensing

A new satellite-based analytical framework enables accurate estimation of crop sowing and emergence dates at the field scale. By integrating daily synthetic satellite imagery with machine-learning models, researchers reconstructed vegetation dynamics and extracted key crop phenological stages. The approach allows agricultural monitoring systems to infer early growth events that are difficult to detect directly, offering improved tools for crop management, yield forecasting, and large-scale agricultural monitoring.

Understanding crop phenology—the timing of key developmental stages such as germination, growth, and senescence—is essential for agricultural management. Accurate knowledge of crop calendars helps optimize irrigation, fertilization, disease monitoring, and yield prediction. Traditional approaches rely on field observations or ground-based monitoring systems, but these methods are often limited in spatial coverage and require intensive labor. Satellite remote sensing provides large-scale monitoring capabilities, yet detecting early crop stages such as sowing and emergence remains difficult because satellite pixels capture mixed signals from soil and sparse vegetation. Cloud cover and data gaps further complicate time-series analysis. Due to these challenges, there is a need to develop new methods capable of accurately estimating sowing and emergence dates using satellite observations.

Researchers from Mississippi State University and collaborating institutions reported a new framework for estimating crop sowing and emergence dates using satellite observations. The study, published (DOI: 10.34133/remotesensing.0878) on March 11, 2026 in the Journal of Remote Sensing, integrates daily synthetic Harmonized Landsat Sentinel-2 (HLS) imagery with machine-learning models to reconstruct vegetation dynamics across agricultural fields. By analyzing vegetation index time series, the framework infers early crop development stages that are typically difficult to detect from space. The technology addresses a major challenge in remote sensing–based agricultural monitoring: identifying the start of the crop growth cycle accurately at large spatial scales.

The research introduces an operational pipeline that combines satellite time-series reconstruction with phenological modeling to estimate crop planting timelines. The method first reconstructs continuous vegetation index data from Landsat and Sentinel-2 imagery, filling gaps caused by cloud cover. From the reconstructed time series, six phenological stages—greenup, mid-greenup, maturity, senescence, mid-greendown, and dormancy—are extracted using an asymmetric double-sigmoid model. Machine-learning algorithms then infer sowing and emergence dates based on the relationships between these phenological stages.

Among the tested models, elastic net regression achieved the best performance, predicting sowing and emergence dates with an average error of about ±10 days. The approach successfully estimated crop calendar events across large corn and soybean fields in the United States, demonstrating strong agreement with ground observations from PhenoCam monitoring sites.

The researchers built the framework using daily synthetic time series derived from Harmonized Landsat Sentinel-2 (HLS) data, which combine observations from Landsat 8/9 and Sentinel-2 satellites at a spatial resolution of 30 meters. Because satellite observations are frequently affected by cloud contamination, the team tested four gap-filling approaches—median interpolation, polynomial regression, harmonic modeling, and Light Gradient Boosting Machine (LightGBM)—to reconstruct continuous vegetation index signals.

The polynomial method produced the most accurate reconstructions, preserving seasonal vegetation dynamics while minimizing noise in the time series. These reconstructed data were then used to calculate the Enhanced Vegetation Index (EVI) and derive phenological curves representing crop growth cycles.

To validate the approach, the researchers compared satellite-derived phenological stages with ground observations from 20 PhenoCam monitoring sites across 13 U.S. states. The comparison showed strong agreement between satellite and ground measurements, with a coefficient of determination (R²) of 0.94 and a bias of approximately 12 days.

Using the phenological stages as predictors, machine-learning models were trained to estimate sowing and emergence dates. The best model was then applied to thousands of agricultural fields, successfully mapping planting timelines across large agricultural regions.

"Our framework demonstrates that early crop development stages can be inferred indirectly from later phenological signals," the researchers noted. "Even though sowing and emergence are difficult to observe directly from satellite imagery, the seasonal growth trajectory contains enough information to reconstruct these dates." The team emphasized that the approach enables scalable monitoring of crop calendars across large regions, which could significantly improve agricultural forecasting and management strategies.

The study used daily synthetic vegetation index time series derived from Harmonized Landsat Sentinel-2 imagery collected between 2021 and 2023. After cloud removal, four gap-filling algorithms were tested to reconstruct missing data. Crop phenological stages were extracted using an asymmetric double-sigmoid model applied to Enhanced Vegetation Index curves. Ground observations from 20 PhenoCam sites were used to validate satellite-derived phenology. Three machine-learning models—multiple linear regression, elastic net regression, and support vector machines—were trained using leave-one-out cross-validation to estimate sowing and emergence dates.

The proposed framework could significantly enhance large-scale agricultural monitoring and decision-making. Accurate knowledge of sowing and emergence dates enables better crop growth modeling, yield forecasting, and climate risk assessment. The system could also support early detection of crop stress, disease outbreaks, and extreme weather impacts. With further refinement, the method could be integrated into global agricultural monitoring platforms and precision agriculture systems. As satellite observations and artificial intelligence technologies continue to advance, such data-driven tools may become essential for ensuring food security and improving agricultural sustainability worldwide.

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References

DOI

10.34133/remotesensing.0878

Original Source URL

https://spj.science.org/doi/10.34133/remotesensing.0878

Funding information

This work is supported by the Data Science for Food and Agricultural Systems program, project award no. 2024-67021-42530, and Soil Health program, project award 2023-67019-39169, from the USDA's National Institute of Food and Agriculture. U.R.V.A., L.B.F., and V.S.M. were partially supported by the USDA Agricultural Research Service (nos. 58-0200-0-002 and 58-6060-3-005). Y.Y. is partially supported by the NASA Acres project (80NSSC23M0034). I.D.A.S. was grateful to the Brazilian National Council of Scientific and Technological Development (CNPq) for the Research Productivity Fellowship (310042/2021-6).

About Journal of Remote Sensing

Journal of Remote Sensing, an online-only Open Access journal published in association with AIR-CAS, promotes the theory, science, and technology of remote sensing, as well as interdisciplinary research within earth and information science.

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Journal

Journal of Remote Sensing

DOI

10.34133/remotesensing.0878 

Subject of Research

Not applicable

Article Title

Operational Framework for Field-Scale Crop Sowing and Emergence Date Estimation Using Daily Synthetic Harmonized Landsat Sentinel-2 Time Series