Georgia Tech researchers say the new policy marks a major step forward in climate adaptation, especially for heat-vulnerable communities, and could help position Atlanta as a national leader in urban resilience.
”On any given summer afternoon, temperatures in Atlanta’s intown neighborhoods can be as much as 15 degrees Fahrenheit higher than in the city’s most forested areas,” said Brian Stone, professor in the School of City and Regional Planning and associate director of Georgia Tech’s Center for Urban Resilience and Analytics.
That spike is partly due to the urban heat island effect — a phenomenon driven by heat-trapping materials like concrete, asphalt, and dark rooftops, combined with the loss of trees and natural landscapes. The impacts are not just uncomfortable — they’re dangerous. Extreme heat is now one of the deadliest forms of weather in the U.S., with disproportionate effects on low-income communities, elderly residents, and those without access to air conditioning.
According to Patrick Kastner, assistant professor in the School of Architecture, rooftops are key contributors. “A major driver [of heat buildup] is dark, heat-absorbing material that stores solar energy during the day and then re-radiates it at night. If you look at a satellite image, for most of the day rooftops have more exposure to the sun than building facades — so the material choice there matters a lot.”
Stone and his students conducted modeling that found that widespread adoption of cool roofs across Atlanta could lower summer afternoon temperatures by more than 2 degrees Fahrenheit in many neighborhoods. That’s comparable to findings in other global cities like London, where cool roofs have reduced average temperatures by up to 2 degrees Celsius (3.6 F).
But cool roofs are only one part of a broader urban cooling strategy. In the same study, Stone’s team showed that planting trees in just half of Atlanta’s available planting zones could yield an even more dramatic effect, reducing temperatures by 4 F or more in some areas.
“Cool roofs are highly effective, but pairing them with increased urban tree cover would multiply the benefits, especially for neighborhoods currently lacking shade,” Stone said.
Atlanta’s ordinance requires cool roofing materials on new commercial construction and when existing commercial roofs are replaced. While that may sound like a technical design tweak, Stone emphasized its equity implications.
“Residents in South and West Atlanta, where tree canopy is sparse, and energy costs take up a larger share of household income, stand to gain the most,” Stone said. “When a cool roof is installed as part of a required roof replacement, those households will see meaningful reductions in cooling costs month after month.”
Kastner added that cool roofs could ease pressure on the electrical grid, lowering peak energy demand required for cooling during extreme heat and possibly reduce the risk of outages.
Stone noted that cool roofs tend to extend the life of roofing materials by limiting thermal degradation. However, he and Kastner also flagged some trade-offs.
For example, highly reflective coatings can create glare, especially on sloped roofs near neighboring buildings. The ordinance accounts for this by setting different standards for flat and pitched roofs. Maintenance is another consideration: over time, reflective coatings may degrade or become dirty, requiring periodic cleaning to maintain performance.
“Aesthetics and material compatibility may also challenge adoption when it comes to historic buildings or for roofs already outfitted with solar panels,” Kastner said. “But advancements in roofing technology, including high-performance materials that aren’t plain white, offer more flexible options than ever before.”
While cities like New York and Chicago have implemented cool roof programs for over a decade, Atlanta’s proposed ordinance is one of the most comprehensive in the country — applying to all roof types, not just flat industrial ones.
“Atlanta is steadily emerging as one of the most climate-resilient cities in the U.S.,” said Stone, pointing to the city’s urban forest and growing network of floodable parks as complementary resilience strategies. “Adding a best-in-class cool roofing ordinance to that portfolio is a bold step forward.”
And it could spark innovation across the region.
“Georgia Tech is uniquely positioned to help advance climate-resilient design,” Kastner said. “From research on advanced coatings to urban planning tools that target the most heat-vulnerable areas, we’re bringing science and policy together to shape cooler, healthier cities.”
]]>With a keen eye and a passion for geography, Radu Casapu, a graduate student in the School of City and Regional Planning, won the 2025 GeoGuessr World Championship in Copenhagen, Denmark.
The online game challenges players to identify specific locations using Google Street View in a race against the clock and — in multiplayer mode — their opponent. The World Championship tournament brought together the world’s 16 top players, and Casapu entered the tournament as the No. 1 seed after winning the Americas Regional in May.
Each round is a best-of-five match. Casapu hadn’t lost a game in the first three rounds of the tournament entering the final round, which came down to the wire. Tied at 2-2, Casapu correctly identified a Chilean landscape to win the decisive final game and the $50,000 prize.
The Suwanee, Georgia, native has been playing GeoGuessr for nearly a decade, but it wasn’t his first foray into competition. Casapu participated in geography bees in middle and high school before earning his bachelor’s degree in geography from the University of Georgia. Outside the classroom, he says the game becomes a resource that challenges him and helps him learn.
“GeoGuessr is such a holistic game, just like geography is a holistic subject that includes not only physical geography, but also cultural and human geography around the world. The game helps you to study these concepts as well as other areas that provide global context, like architecture, ecology, botany, and other things that I would never have thought I’d start noticing. It gives me a lot of perspective in my own line of work in planning,” he said.
As a first-year graduate student at Tech, Casapu is familiarizing himself with his surroundings. Should he come across a campus location while playing the GeoGuessr, he believes he’d first recognize the architectural style and the brickwork of the Institute’s historic buildings.
After completing his master’s degree, Casapu will pursue a career as a planner at the city or regional level.
The four-year $6.7 million Safety Aware Learning Assured Autonomy for Aviation project will be headed up by Hever Moncayo from Embry-Riddle Aeronautical University, and include collaborations with Georgia Tech, the University of Texas, Arlington, the University of Southern California, and Collins Aerospace.
“I’m thrilled to join forces and combine our multifaceted expertise to enhance the safety of Advanced Air Mobility vehicles. Our research is paving the way to make them a reality,” Vamvoudakis stated. “This ULI will bring together experts from academia and industry to speed up progress in aviation safety, improve the reliability and autonomy of future air mobility, and facilitate the integration of autonomous safety systems into commercial and regulatory standards.”
The project will investigate the significant knowledge gaps that have slowed down the national airspace’s use of AAM vehicles such as drones and air taxis. Vamvoudakis and his team will create smart safety system software that can learn independently. This system will help monitor, manage, and control these vehicles safely and reliably. It will also produce national safety guidelines to ensure the vehicles follow safe flight paths and make harmless decisions based on their own learning. Additionally, they will allow vehicles to autonomously adjust their own actions to ensure safety within specific operational limits. The idea is that future AAM vehicles will use smart, non-traditional components to stay safe and perform well, even in unexpected situations and emergencies. Establishing an intelligent system that can diagnose and predict issues independently will be crucial. This system will help ensure these vehicles meet their mission goals safely, despite challenges like unpredictable environments.
This ULI research effort will support the Aeronautics Research Mission Directorate’s (ARMD) outcome for 2020-2035: Initial safe and efficient integration of highly automated vehicles into the National Airspace System (NAS) by introducing aviation systems with bounded autonomy, capable of carrying out function-level goals.
This is Vamvoudakis’ second ULI. He is a part of the Safe and Secure Autonomy Project that is still active.
Co-Pis: K. Merve Dogan, Maj Mirmirani, and Victor Fraticelli (Embry Riddle Aeronautical University), Kyriakos G. Vamvoudakis (Georgia Institute of Technology), Nicholas Gans and Yijing Xie (University of Texas, Arlington), Petros Ioannou (University of Southern California), and Kevin Kronfeld (Collins Aerospace) will play a crucial role in this collaborative effort.