The study leverages a formidable dataset of over two million temperature measurements collected at one-minute intervals, allowing for a granular analysis of indoor thermal conditions across two distinct informal settlements in Bihar. Researchers employed two simple yet innovative interventions: the application of radiant foil inside homes and the use of Mylar blankets, both chosen for their reflective properties and ease of installation. The extensive data collection effort ensured that the results captured the subtle but vital dynamics of indoor temperature fluctuations over different times of day and environmental conditions, offering robust evidence on the efficacy of these materials in mitigating heat stress.

Radiant foils are thin, multi-layered sheets designed to reflect radiant heat, thereby reducing heat transfer through walls and roofs, which are typically constructed from metal or other heat-absorbing materials in informal settlements. By reducing the indoor temperature by an average of 1.24 degrees Celsius, the radiant foils demonstrated a meaningful ability to improve thermal comfort. This temperature reduction not only lowers the risk of heat-related illnesses but also enhances overall quality of life, especially for the most vulnerable groups such as children, the elderly, and those with pre-existing health conditions.

Mylar blankets, commonly used as emergency thermal blankets, were tested for their potential as an affordable heat mitigation strategy. These blankets, made from metalized polyester film, are reflective and lightweight, making them remarkably easy to deploy within existing structures. Despite achieving a slightly lower temperature reduction compared to radiant foils—an average decrease of 0.97 degrees Celsius—Mylar blankets still represented a significant improvement in indoor thermal conditions. Their widespread availability and low cost make them a highly scalable solution for informal settlements facing recurrent heat waves.

The implications of these findings extend beyond just temperature control. Heat stress in urban informal settlements contributes to increased morbidity and mortality rates, especially during peak summer months. By lowering indoor temperatures, these interventions can reduce the physiological strain experienced by residents, ultimately contributing to better health outcomes. Moreover, reducing the need for electricity-dependent cooling can also alleviate financial burdens and decrease greenhouse gas emissions, helping to address climate change through a synergistic approach that benefits both people and the planet.

An important dimension of this research is its focus on rapid deployability, a critical factor in informal settlements where residents often live in precarious conditions with transient housing. The modularity and lightweight nature of both radiant foils and Mylar blankets allow residents or aid organizations to implement the cooling solutions swiftly, without the need for professional installation or extensive structural modifications. This ease of deployment is crucial for emergency responses to heat waves, ensuring that vulnerable populations receive timely relief when heat events are most severe.

The researchers’ choice to study two communities in Bihar provides valuable contextual insights into the challenges endemic to Indian informal settlements, which are representative of many similar urban areas in the Global South. These communities are often deprived of basic urban services, with high population density and poor housing conditions exacerbating heat exposure. The study’s setting underscores the real-world applicability of the interventions and highlights the importance of context-specific adaptation solutions that resonate with local socio-economic realities.

This investigation furthermore underscores the transformative potential of combining rigorous scientific measurement with community engagement. By involving residents in the deployment and maintenance of the interventions, the project fostered a sense of ownership and awareness about heat risk mitigation. This participatory approach is essential for ensuring the long-term sustainability and acceptance of such interventions, as community buy-in dramatically increases the likelihood of adoption and continued use.

From a technical standpoint, the minute-level temperature data enabled a detailed comparative analysis of indoor heat dynamics before and after the installation of materials. This high-resolution monitoring revealed not only peak temperature reductions but also delayed heat gain, meaning homes stayed cooler for longer periods into the evening. This effect is particularly important because it enhances nighttime comfort, which is crucial for rest and recovery, especially in settings where outdoor temperatures remain elevated after sunset.

The study also contributes valuable knowledge to the broader discourse on climate adaptation in urban settings. While much policy attention has focused on large-scale infrastructure projects and high-tech solutions, this research reaffirms the critical role that low-tech, cost-effective interventions can play in safeguarding vulnerable communities. The findings encourage stakeholders—from urban planners to public health officials—to consider these strategies as integral components of heat resilience planning.

In addition to its practical outcomes, the research methodology represents a model for future climate adaptation studies. The combination of comprehensive environmental monitoring and on-the-ground intervention trials offers a replicable framework for testing low-cost technologies in varied geographic and social contexts. Such approaches are essential for scaling solutions globally and tailoring them to diverse urban informal settlements that share common vulnerabilities but differ in specific environmental and cultural conditions.

In reflecting on the implications of these findings, it is clear that tackling heat stress requires multifaceted strategies that integrate environmental science, material technology, social engagement, and policy innovation. The study’s success in demonstrating tangible indoor temperature reductions using accessible materials establishes a new benchmark for what is achievable in climate adaptation interventions in marginalized urban environments.

Looking ahead, there is potential for further optimization of these materials and exploration of hybrid approaches that combine reflective foils or blankets with passive ventilation enhancements or shading devices. Integrating these techniques could amplify cooling effects while maintaining affordability and ease of implementation, thus broadening the arsenal of tools available to vulnerable communities facing runaway urban heat challenges.

Ultimately, the research led by Ang, Sparsh, Wang, and colleagues offers a beacon of hope in the climate crisis, illustrating how ingenious, low-cost solutions can empower some of the world’s most vulnerable populations to better withstand the intensifying impacts of global warming. By translating scientific insights into practical, scalable improvements in human comfort and health, this work embodies the promise of climate resilience grounded in equity and innovation.

As urban areas continue to expand and climate threats escalate, the urgency of developing and disseminating affordable cooling interventions will only grow. This study provides a vital foundation and call to action for scientists, policymakers, and communities alike to prioritize accessible strategies that protect health and livability in informal settlements worldwide.

Subject of Research: Heat stress mitigation interventions for urban informal settlements in Bihar, India.

Article Title: Low-cost interventions for heat stress mitigation in urban informal settlements.

Article References:
Ang, Y.Q., Sparsh, Wang, T. et al. Low-cost interventions for heat stress mitigation in urban informal settlements. Nat Cities (2026). https://doi.org/10.1038/s44284-025-00370-3

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s44284-025-00370-3

This novel hydrogel material boasts an all-in-one architecture, masterfully combining the physics of sky radiative cooling and the thermodynamics of water evaporation in a single, versatile matrix. Unlike conventional radiative cooling films that primarily rely on emitting thermal radiation to the cold outer space, this hydrogel also harnesses evaporative cooling—leveraging the latent heat absorption during water evaporation to further suppress temperatures above ambient levels. Importantly, under identical environmental conditions, this dual-mode cooling approach effectuates a remarkable 12.0°C temperature reduction compared to standalone radiative cooling films, paving the way for significant breakthroughs in outdoor electronic device regulation.

The secret behind the hydrogel’s efficacy lies in its ingenious design and composition. The porous matrix is embedded with hexagonal boron nitride (hBN) nanoplates, which serve as efficient solar reflectors, showcasing a high solar reflectance of 87.2%. Simultaneously, lithium chloride (LiCl) within the hydrogel functions as a moisture adsorption-desorption agent, enabling the material to autonomously harvest atmospheric water vapor during nighttime. This moisture is subsequently available for evaporation during daylight, orchestrating a passive water cycle that sustains evaporative cooling without requiring any external water supply—a crucial feature that dramatically expands the hydrogel’s applicability in remote or resource-constrained settings.

Moreover, the material’s thermal emittance in the longwave infrared region (LWIR) reaches an impressive 93.7%, allowing it to efficiently radiate dissipated heat into the vast cold sky. This synergy between high solar reflectance and thermal emittance propels heat dissipation to new heights. The optimized thickness of 6 mm and carefully calibrated water content of 5 weight percent strike an ideal balance between thermal conductivity and water retention, ensuring the hydrogel’s performance is both consistent and robust under varying environmental conditions.

Beyond its cooling capabilities, the hydrogel demonstrates outstanding flame retardancy qualities—an essential breakthrough considering the increasing fire risks associated with outdoor electronic infrastructure. When exposed to open flames, the latent heat absorbed through water evaporation prevents surface temperatures from exceeding 100°C, effectively averting ignition. This passive fire protection mechanism affords an additional safety layer, mitigating thermal runaway events and ensuring the longevity and reliability of high-power devices like 5G base stations, photovoltaic modules, and battery enclosures.

Mechanical versatility is another hallmark of this hydrogel. It exhibits notable flexibility, allowing conformal attachment to diverse substrates including glass, metal, and wood. The strong adhesion and stretchability imbue the hydrogel with the resilience required for real-world applications, accommodating the dynamic physical stresses that outdoor installations routinely encounter.

From an economic perspective, the team prioritized scalability and cost-effectiveness. Using readily available materials such as PDMAPS polymer and mineral fillers like hBN and Al₂O₃, the production cost amounts to a mere $66 per square meter per millimeter thickness. This affordability is crucial to facilitate widespread adoption across industries seeking sustainable thermal management solutions without prohibitive upfront investments.

Extensive outdoor testing validates the hydrogel’s exceptional performance, consistently delivering a 20.9°C temperature reduction compared to bare substrates, and maintaining superiority over conventional radiative cooling films. Crucially, these results hold across continuous day-night cycles, attesting to the material’s all-day operational capability fueled by its integrated atmospheric water harvesting function.

Looking ahead, the research team is keenly aware of the challenges that must be overcome to transition from laboratory prototypes to commercial platforms. Durability enhancements, particularly through corrosion-resistant coatings, are vital to void degradation from prolonged environmental exposure. Beyond this, innovations aimed at further minimizing material costs could accelerate scaling, enabling mass production that meets the demands of global markets focused on green technologies.

The implications of this hydrogel extend well beyond electronics cooling. Its passive, water-autonomous design principles could inspire a new class of smart materials for architecture, wearable devices, and even aerospace applications where thermal regulation and fire safety are paramount. This integrated approach channels the twin forces of photonics and water chemistry, heralding a future where sustainable cooling is not a luxury but a ubiquitous reality.

The work from Professor Meijie Chen’s team thus represents a significant stride toward reimagining how we combat excessive heat and fire hazards in harsh environments. By bridging advanced polymer chemistry with precision nanoscale engineering, they have crafted a multifunctional hydrogel platform that sets a new standard for thermal management technology. As climate pressures mount and energy efficiency becomes non-negotiable, innovations like this photonic hydrogel will be critical enablers for resilient, safe, and sustainable outdoor electronics infrastructure worldwide.

Subject of Research: Radiative and evaporative cooling in photonic hydrogels for thermal management and flame retardancy
Article Title: Radiative Coupled Evaporation Cooling Hydrogel for Above‑Ambient Heat Dissipation and Flame Retardancy
News Publication Date: 1-Sep-2025
Web References: 10.1007/s40820-025-01903-0
Image Credits: Qin Ye, Yimou Huang, Baojian Yao, Zhuo Chen, Changming Shi, Brian W. Sheldon, Meijie Chen*

Keywords

Hydrogels, Radiative Cooling, Evaporative Cooling, Thermal Management, Flame Retardancy, Atmospheric Water Harvesting, Photonic Materials, Hexagonal Boron Nitride, Lithium Chloride, Outdoor Electronics Cooling

The novel approach hinges on the manipulation of a transparent silicone polymer known as PDMS (Polydimethylsiloxane), processed with laser output intensity adjustments. When exposed to high-intensity laser light, the polymer’s surface transitions into a white porous structure that reflects solar radiation and emits thermal energy, thus generating cooling effects conducive to maintaining lower temperatures in hot outdoor environments. On the other hand, applying a low-intensity laser causes the formation of a black porous structure that serves the opposite function, primarily absorbing sunlight to produce heat.

This dual-functionality not only simplifies the complexity typically associated with conventional thermal management methodologies, which often require different materials and multifaceted processing to achieve the same ends, but it also suggests a new pathway towards zero-energy thermal solutions. Given the pressing realities of climate change and energy crises, the need for sustainable methods to manage temperature without additional electrical drain has never been more critical. The developed technology promises to create just such solutions—enabling environments to remain dramatically cooler during scorching summer months and warmly insulated during frigid winters.

The implications of this research extend well beyond merely regulating ambient temperatures. The team rigorously tested their novel material’s capabilities in real-world environments. Under the glaring sun, the cooling surface achieved an average temperature of 5.89 degrees Celsius lower than the surrounding environment, while the heating surface heated itself to 58.1 degrees Celsius. Such remarkable thermal regulation demonstrates not only the practicality but the outstanding performance of their novel thermal management solution.

Further simulations indicate promising potential for economic savings in energy costs should this thermal management technology be implemented in building construction. The simulations projected a staggering annual reduction of up to 26.5% in heating and cooling energy expenses when incorporating this innovative material into rooftops. This not only illustrates potential initial investment returns but also underscores the technology’s promise to contribute significantly to energy efficiency and sustainability in architectural designs.

Additionally, the incorporation of this technology may expand into ‘plus-energy’ applications. By harnessing the temperature gradient formed between the surfaces – one cooling and the other heating – researchers envision creating solar-driven thermoelectric generators capable of producing electricity from thermal differences. Such advancements could aid in meeting energy demands while simultaneously reducing reliance on traditional electrical grids.

The research’s significance is compounded by its potential applications in various sectors, from building energy efficiency to outdoor equipment thermal stability and renewable energy generation—even extending into sophisticated systems such as solar-assisted desalination processes. As a result of the simplicity and cost-effectiveness of the technology, it holds vast promise for widespread implementation across diverse fields that seek to reduce their carbon footprints.

Professor Seung Hwan Ko emphasized the groundbreaking nature of this technology in redefining thermal management strategies. The ability to seamlessly flip between heating and cooling functions using a standardized material and a singular laser process drives forward the discourse around innovative manufacturing and material science. He stated that this approach opens the door for multiple real-world applications across various industrial sectors, fundamentally altering how we perceive and manage thermal energy.

Lastly, this work underlines the urgency of adapting our technologies and communities for an environmentally sustainable future. With energy usage on the rise and the atmosphere under increasing stress from climate change, innovations such as the one spearheaded by the research team at Seoul National University could represent the kind of paradigm shift that society needs to transition towards a more energy-efficient and ecologically friendly existence.

As the world grapples with both an energy crisis and the escalating consequences of climate change, the emergence of such technologies becomes not just beneficial but essential. At a time when every degree matters in temperature regulation, the implications of this revolutionary technology could represent a quantum leap forward, one that bolsters sustainability while meeting contemporary energy demands. The path forward is illuminated with hope, as this single-material solution sets the stage for the future of energy management.

Subject of Research: Not applicable
Article Title: Monolithic Integration of Radiative Cooling and Solar Heating Functionalities by Laser-induced Pyrolysis
News Publication Date: 20-Aug-2025
Web References: 10.1016/j.joule.2025.102007
References:
Image Credits: © Joule, originally published in Joule

Keywords: Thermal management technology, cooling and heating functions, laser processing, energy efficiency, sustainability, climatic adaptation, polydimethylsiloxane (PDMS), renewable energy, zero-energy technology.

The core principle behind thermogalvanic refrigeration lies in its ability to exploit reversible electrochemical reactions to create an efficient cooling effect. Unlike conventional systems that consume substantial energy, this novel approach operates on a significantly reduced energy input, providing a sustainable alternative that aligns with global efforts to enhance energy efficiency. The researchers believe this technology could be adapted to a wide range of applications, including industrial cooling systems, wearable devices, and even household refrigerators.

Significant to thermogalvanic technology is the process’s ability to produce a cooling effect during a reversible chemical reaction rather than relying on thermodynamic cycles prevalent in standard refrigerators. When specific chemicals are utilized within these thermogalvanic cells, their interactions lead to an absorption of heat, thereby generating an effective cooling effect. As the research team elaborated, they have managed to markedly enhance the cooling capacity of these systems through innovative reengineering of electrolytes.

Senior author Jiangjiang Duan underscored the significance of this breakthrough, noting that while previous research on thermogalvanic technology focused primarily on initial system designs, their latest advancements introduce a more systematic and universal design strategy. By optimizing the chemical components of the thermogalvanic electrolytes, the researchers achieved unprecedented cooling capacities, paving the way for practical applications in commercial settings.

Moreover, the advanced cooling process operates on electrochemical redox reactions involving iron ions, which play a crucial role in the energy conversion that drives the refrigeration effect. By meticulously controlling the interactions of these ions during the electrochemical processes, the research team succeeded in maximizing the energy efficiency of their system. The two-phase reactions produce significant thermal changes, allowing the system to effectively cool the surrounding electrolyte solution.

Remarkably, the researchers reported a cooling performance that accounted for a temperature drop of 1.42 K. This represents a substantial improvement over previously established thermogalvanic systems, which typically demonstrated a cooling capacity of merely 0.1 K. This advancement not only showcases the innovative nature of their work but also illustrates the promising potential of thermogalvanic technology in advancing energy-efficient refrigeration solutions.

To achieve this leap in cooling performance, the researchers carefully selected electrolyte compositions that support enhanced ions’ behavior. By exploring various combinations of solutes and solvents, they concluded that utilizing hydrated iron salts mixed with perchlorate within a nitrile solvent resulted in a markedly improved cooling effect. This novel configuration allowed for increased mobility of iron ions, thereby optimizing the electrochemical reactions crucial for effective refrigeration.

Looking toward the future, Duan’s team is also focused on exploring new experimental designs and materials that could further enhance the cooling performance of their thermogalvanic systems. They are already in discussions to collaborate with industrial partners to facilitate the commercialization of this innovative refrigeration technology. The team hopes to refine the scalability, stability, and overall system-level design of their invention to ensure successful practical implementation in real-world applications.

The research has generated excitement not only within scientific circles but also among commercial stakeholders who recognize the potential for thermogalvanic refrigeration solutions to transform the industry. As the team continues its quest to improve and adapt their systems, the integration of thermogalvanic technology into broader applications remains a tantalizing prospect, signaling a new frontier in sustainable energy research.

Researchers are optimistic that as they continue advancing their experimental systems, the viability of thermogalvanic refrigeration will prove increasingly feasible for everyday use, signaling a shift towards energy-efficient technologies that benefit both consumers and our environment. The pathway paved by this study will undoubtedly inspire further innovations in energy conservation and pollution reduction in refrigeration technologies.

In summary, the work from the Huazhong University of Science and Technology is a landmark achievement in the field of electrochemical refrigeration. The ability to harness thermogalvanic processes not only opens new avenues for highly efficient cooling solutions but also serves as an illustration of the endless possibilities that arise when scientific inquiry aligns with the pressing need for sustainable technology. The research has laid a strong foundation for further exploration and commercial interest, ensuring that the journey toward more efficient refrigeration systems is just beginning.

Subject of Research: Thermogalvanic electrolytes for electrochemical refrigeration
Article Title: Solvation entropy engineering of thermogalvanic electrolytes for efficient electrochemical refrigeration
News Publication Date: January 30, 2025
Web References: Joule journal
References: Zeng et al. "Solvation entropy engineering of thermogalvanic electrolytes for efficient electrochemical refrigeration," Joule.
Image Credits: Yilin Zeng

Keywords

Sustainable energy, Electrolytes, Electrochemical reactions, Energy efficiency, Refrigeration technology, Thermogalvanic cooling, Renewable energy solutions, Environmental impact.