The suffocating grip of extreme heat, a stark manifestation of accelerating climate change, is prompting urgent innovation, with MIT researchers spearheading a multi-pronged initiative to develop accessible and sustainable cooling technologies, particularly for vulnerable populations in the Global South. This critical endeavor gained palpable urgency for MIT mechanical engineering Professor Kripa Varanasi during a June 2024 visit to New Delhi. Landing in the dead of night, Varanasi was immediately confronted by a scorching 104-degree Fahrenheit atmosphere, a prelude to daytime temperatures that frequently soared to an oppressive 122 F. His personal discomfort mirrored a growing global crisis, reigniting a deeply personal commitment. "This was June, and it was crazy. It was so hot for the whole meeting that I never left the hotel," Varanasi recounted, a sharp contrast to his childhood memories in India where such relentless heat was uncommon. "When I grew up in India, it was not like this. That kind of inspired me." This experience underscored the profound and immediate need for novel cooling solutions, galvanizing his involvement in the MIT Climate Project’s Critical Cooling initiative.
The Genesis of Critical Cooling: A Response to a Global Emergency
The MIT Climate Project, recognizing the escalating threat of heat fatalities, particularly among vulnerable populations lacking access to active cooling, launched its Critical Cooling initiative last year. This program, which awarded seed funding totaling $450,000 across four distinct projects, aimed to foster truly innovative approaches to a problem with far-reaching humanitarian and environmental implications. Christoph Reinhart, the Terri and Alan Spoon Professor of Architecture and Climate and head of MIT’s Sustainable Design Lab (SDL), was instrumental in championing this effort and served as the faculty lead. Reinhart explained that the term "critical cooling" emerged from a collaboration between SDL and Harvard’s Human Rights Entrepreneurs Clinic, reflecting the humanitarian imperative behind the scientific pursuit. "It is motivated by the fact that climate change increasingly causes heat fatalities, primarily among vulnerable populations, who lack access to active cooling," he stated. "The impact that MIT can have by ‘cooling people, not spaces’ is enormous." This guiding philosophy shaped the grant program, providing six months of funding for each team to develop proof-of-concept prototypes and explore groundbreaking solutions.
The urgency of this initiative is underscored by alarming global trends. The World Meteorological Organization (WMO) has consistently reported record-breaking temperatures, with 2023 confirmed as the hottest year on record, a trend expected to continue. Heatwaves are becoming more frequent, more intense, and longer-lasting, disproportionately affecting regions in the Global South that often lack robust infrastructure, reliable power grids, and affordable cooling options. According to the United Nations, extreme heat is already a leading cause of weather-related deaths globally, and its impact on public health, economic productivity, and social equity is projected to worsen dramatically without effective intervention.
A Collaborative Quest for Solutions
To ensure the solutions developed were practical, scalable, and responsive to real-world needs, the Critical Cooling initiative fostered a robust collaborative environment. In partnership with the Abdul Latif Jameel Poverty Action Lab (J-PAL), led on J-PAL’s side by Senior Policy Manager Andre Zollinger, the MIT teams commenced their work with a pivotal workshop. This gathering brought together a diverse array of stakeholders, including representatives from the World Bank, influential leaders from various nations in the Global South, industry experts, and engineers brimming with innovative ideas. This collaborative crucible ensured that the research was grounded in the realities of those most affected, focusing on affordability, energy efficiency, and environmental sustainability.
Liana Frey, a managing director at the MIT Climate Project, confirmed the significant progress made by all teams, with most successfully producing initial prototypes within the six-month funding window. "We’re continuing to look at different ways of proceeding with the work," Frey noted, signaling ongoing efforts to further develop and secure additional funding for these promising concepts. The collective aim is not merely to invent new technologies but to ensure their widespread adoption and impact where they are most desperately needed.
Diverse Technological Pathways to a Cooler Future
The four MIT-backed projects represent a spectrum of innovative approaches, each targeting different aspects of the cooling challenge, from personal devices to building-scale systems and revolutionary refrigerants.
1. Wearable Personal Cooling: Cooling the Individual, Not the Environment
Kripa Varanasi’s project epitomizes the "cooling people, not spaces" philosophy. His team focused on developing a wearable personal cooling system, drawing inspiration from nature – specifically, how an elephant uses its massive ears to dissipate heat and cool its blood. This approach dramatically reduces energy consumption compared to conventional air conditioning. Varanasi’s device consumes a mere 33 watts, a stark contrast to a typical room air conditioner’s approximately 1,000 watts.
The economic implications of this technology are potentially transformative. Varanasi estimates that the prototype, if manufactured with U.S. materials, would cost around $20. However, by sourcing local materials in India, the cost could plummet to less than $1 per unit. This affordability opens up pathways for broad distribution and accessibility, particularly for low-income populations. Varanasi envisions governments purchasing these garments in bulk for distribution to communities. Local entrepreneurs could then establish charging stations to recharge the devices after a night’s wear, creating micro-economies around the technology. Furthermore, local businesses could be empowered to manufacture the systems themselves. The washable nature of the garments, with the cooling material separable, adds to their practicality and hygiene. This innovation could provide crucial relief, enabling individuals to achieve at least a restorative night’s sleep even amidst extreme heat, a critical factor for health and productivity.
The proof-of-concept demonstrated remarkable efficacy. Using a simulated foot equipped with a heater, Varanasi’s team successfully measured the cooling effect. "We were able to keep it in the zone that we need for the body to stay cool," he explained. "So our initial prototype that we were able to build with this funding showed that this can become a viable solution." The underlying material, widely available but treated using a novel process developed by his team, represents a significant scientific breakthrough. "It was a fundamental science bottleneck that we were able to overcome, which makes it possible," Varanasi asserted. Beyond garments, this material could be integrated into other applications, such as cooling sleeping bags. Varanasi is actively exploring commercialization pathways, recognizing that "ultimately, to make anything work, it has to be a business, otherwise good ideas can die. It has to be a good business and a sustainable business."
2. Subsurface Wells for Passive Cooling: Harnessing Earth’s Stability
Professor Yet-Ming Chiang, the Kyocera Professor of Materials Science and Engineering, explored a different, yet equally innovative, avenue: leveraging the Earth’s natural thermal stability. His research focused on the potential of subsurface wells incorporating heat-absorbing materials. The principle is elegant: underground temperatures are significantly cooler and more stable than ambient surface temperatures, especially during heatwaves. By circulating air or a heat transfer fluid through these subsurface wells, it’s possible to supply spaces with air far below peak ambient temperatures, using substantially less energy than conventional evaporation-compression heat pumps.
This approach offers a promising alternative for both small apartment buildings and single-family homes, particularly in regions like India and other parts of the Global South where energy infrastructure can be limited or unreliable. The beauty of Chiang’s concept lies in its passive or low-energy nature, minimizing reliance on electricity grids that are often strained during peak heat events. Such systems could dramatically reduce energy demand for cooling, alleviate pressure on grids, and offer a more resilient solution against power outages that often coincide with the hottest periods. The materials science aspect is critical here, focusing on efficient heat absorption and transfer within the subterranean environment to maximize cooling output.
3. Caloric Materials for Energy-Efficient, HFC-Free Air Conditioning
Asegun Henry, the George N. Hatsopoulos Professor in Thermodynamics, addressed two major challenges with conventional air conditioning: energy inefficiency and the environmental impact of hydrofluorocarbon (HFC) refrigerants. HFCs are potent greenhouse gases, often thousands of times more impactful than carbon dioxide, and their leakage contributes significantly to global warming. Henry’s innovative approach seeks to eliminate these harmful chemicals by utilizing a cheap, widely abundant solid "caloric" material – specifically, rubber – to achieve a cooling effect.
Caloric materials operate on the principle that they can change temperature when subjected to external stimuli (like mechanical stress in the case of elastocaloric materials such as rubber). By stretching and releasing rubber, heat can be absorbed and then dissipated, creating a cooling cycle. Crucially, Henry’s system then employs plain water as an efficient heat transfer fluid, further enhancing its environmental credentials and reducing operational costs. This technology offers a radical departure from vapor-compression cycles that have dominated cooling for decades. The initial target market for this HFC-free, energy-efficient system is single-family houses and apartment buildings, but Henry also sees potential for larger-scale applications, including the intensive cooling needs of data centers, which are rapidly growing energy consumers. The implications for reducing the carbon footprint of cooling infrastructure are immense.
4. Next-Generation Refrigerants: Eliminating Greenhouse Gas Impact
Professor Gang Chen, the Carl Richard Soderberg Professor of Power Engineering, tackled the core problem of refrigerants directly. Existing air conditioning units are not only expensive and power-hungry but also rely on refrigerants that are powerful greenhouse gases. The problem is exacerbated when these devices reach their end-of-life, as coolants are highly likely to leak out during disposal, adding to their global warming contribution. Chen’s approach proposes a fundamental shift: using a completely different kind of chemical refrigerant that has zero greenhouse impact.
Chen acknowledged that he had theoretical ideas for such refrigerants but lacked the opportunity for experimental validation until the Critical Cooling grant. The funding enabled his team to build and test three prototypes. While still in the developmental phase, Chen expressed cautious optimism. "I’m not at the stage where I can say that I know this will work," he admitted, but based on the initial experiments, he is eager to proceed with building a further prototype. If successful, this breakthrough could revolutionize air conditioning technology worldwide, offering a truly climate-friendly cooling solution. The demand for such technology is rapidly escalating; Chen noted that while only about 8 percent of the 2.8 billion people in the hottest parts of the world currently have access to air conditioning, the market for AC units is expected to triple or quadruple in the coming years. This surge, if powered by conventional refrigerants, would dramatically increase global warming emissions, currently accounting for 3 to 4 percent of the total. Chen’s work aims to preempt this looming environmental catastrophe.
Broader Impact and Implications for the Global South
The "critical cooling" initiative extends beyond technological breakthroughs; it is deeply intertwined with socio-economic development and human rights. The majority of the 2.8 billion people living in the world’s hottest regions face a dual challenge: limited access to reliable or affordable power and high levels of poverty. This confluence of factors makes them exceptionally vulnerable to the health and economic consequences of extreme heat. Heat stress leads to reduced productivity, increased healthcare costs, and, tragically, a rise in heat-related fatalities. The World Bank estimates that productivity losses from heat stress could cost the global economy trillions of dollars annually by 2050, with developing nations bearing the brunt.
The MIT Climate Project’s focus on solutions that are affordable, energy-efficient, and environmentally benign is therefore paramount. Varanasi’s wearable cooling, for instance, offers a localized, low-power solution that can provide immediate relief without straining fragile power grids or incurring high costs. Chiang’s subsurface wells offer a passive, resilient cooling method. Henry’s and Chen’s work tackles the systemic issues of energy consumption and greenhouse gas emissions from conventional AC, aiming for global scalability. These innovations hold the potential to improve public health outcomes, enhance labor productivity, particularly in outdoor and manual labor sectors, and foster greater educational attainment by making living and learning environments more tolerable.
The involvement of organizations like J-PAL and the World Bank in the initial workshop highlights the commitment to translating scientific innovation into tangible policy and development impact. Their expertise in poverty alleviation, economic development, and large-scale project implementation is crucial for ensuring that these promising prototypes can navigate the complex pathways from laboratory to widespread adoption.
The Path Forward: Sustained Support for a Growing Urgency
The successful completion of the initial six-month grant period marks a significant milestone, but it is just the beginning. Liana Frey emphasized that the MIT Climate Project is actively exploring various avenues to continue developing and funding these ideas. "There are a lot of people interested in this heat-stress question," Frey stated, acknowledging the escalating global awareness and concern. "It’s just becoming more and more urgent."
The next phase will involve refining the prototypes, conducting more extensive testing, and developing viable commercialization strategies. This will likely require further investment, partnerships with industry, and engagement with governments and non-governmental organizations in the Global South. The vision extends beyond mere technological deployment; it encompasses building local capacity for manufacturing, distribution, and maintenance, thereby fostering sustainable economic development alongside climate resilience.
The MIT Critical Cooling initiative stands as a testament to the power of targeted scientific inquiry and interdisciplinary collaboration in addressing one of humanity’s most pressing challenges. By focusing on innovative, accessible, and sustainable cooling solutions, these researchers are not just mitigating the effects of a warming planet; they are actively working to safeguard human well-being, economic stability, and environmental health for generations to come. The initial successes provide a beacon of hope in a world increasingly grappling with the relentless heat of climate change, proving that with ingenuity and concerted effort, cooler, more equitable futures are within reach.
