A team of engineers and researchers from the University of California, Los Angeles (UCLA) has developed a new method to make outdoor environments feel up to 10 degrees Fahrenheit cooler. This innovative technique aims to maintain a sense of safety and openness while providing relief from extreme heat.
The study, led by UCLA, was featured as the cover story in the June issue of Nature Sustainability. It introduces a new approach to radiant cooling that avoids using dark, enclosed spaces like tunnels. Instead, it utilizes water-cooled aluminum panels combined with see-through, infrared-reflective thin polymer film. This design ensures efficient cooling while maintaining visibility, which is crucial for urban communities.
As climate change intensifies, extreme heat events are becoming more frequent and severe, posing risks to those who spend considerable time outdoors. Active radiant cooling has emerged as a promising solution for outdoor thermal comfort by using surrounding surfaces to absorb heat without conditioning unconfined air. However, traditional radiant cooling structures require opaque panels for effectiveness, raising concerns about practicality and safety. The UCLA team addressed these issues with their new design.
The research received funding from the National Science Foundation and UCLA’s Sustainable LA Grand Challenge’s Heat Resilient LA project.
“This low-cost and scalable design is a practical step beyond shade to help people who have to be outdoors on hot days,” said Aaswath Raman, an associate professor at the UCLA Samueli School of Engineering. “This additional level of cooling can bring some relief in outdoor places where traditional air conditioning simply isn’t possible.”
Field studies were conducted on the UCLA campus and at the San Fernando Swap Meet when temperatures reached the mid-80s Fahrenheit. The team constructed a nearly 10-by-10-foot “tent” with semi-transparent walls made of half-metallized thin polymer film and radiative-cooling sheets for the roof. Hydronic radiant-cooling panels made of aluminum sheets were used to keep the structure cool.
The mean radiant temperature inside the structure was approximately 78 degrees Fahrenheit—more than 10 degrees cooler than what would be experienced due to heat radiating from surrounding surfaces. Participants reported feeling cooler and more comfortable inside this structure compared to being in shade alone.
“Cities need to think about shade as infrastructure,” said V. Kelly Turner, a co-author of the study and associate professor at UCLA Luskin Center for Innovation.
The lead author of the paper is David Abraham, a doctoral student in Raman’s research group at UCLA Samueli. Other contributors include Dr. Mackensie Yore from UCLA Health; Kirsten Schwarz from UCLA Luskin School; Dr. David Eisenman from David Geffen School of Medicine; Walker Wells from Luskin School; Robert Yang, Xin Huang, and Jyotirmoy Mandal from Raman’s group.
