Beating the heat, one tree at a time: Sustainable Triangle Field Site explores heat vulnerability on campus 

July 18, 2024

The 2024 STFS cohort in front of the Old Well.

When you spend time on the University of North Carolina at Chapel Hill’s campus, how much do you think about the trees? Do you stop for a photo when the oak, Davie Poplar and ginkgo leaves change color in the fall? When the cherry blossoms bloom in the spring? But do you ever think about the interactions between trees, climate change, heat, urban planning, environmental justice and your experience on campus? Before their capstone research project at the Sustainable Triangle Field Site, neither did Krystal Lacayo nor Claire Hargrove. 

Lacayo, Hargrove and nine other undergraduate students made up the 2024 Sustainable Triangle Field Site (STFS) cohort. Over the course of a semester, STFS students took classes focused on topics including green architecture, street design, mobility, urban planning, community development and stormwater management. They wrote policy papers, drafted proposals of how they would redesign streets in Chapel Hill for better safety and were briefly introduced to the 3D modeling software SketchUp when tasked with redesigning sites like Carrboro’s Fitch Lumber Yard as multi-use community spaces. STFS students went on field trips, had weekly guest lectures, took internships and conducted research, all while being able to stay on campus. 

“What I think is exciting is that the field site being on Carolina’s campus means that you don’t miss out on all of the cool things that happen in spring semester. You can be here for basketball season, you can participate in student life, you can do it as a senior. You can do a field site, but also do Carolina at the same time,” says STFS Director and Assistant Professor Antonia Sebastian. 

Students Laine Cammack and Claire Hargrove calibrating Pocketlab sensors before collecting heat data on walking routes.

Since the Sustainable Triangle Field Site began collaborating with Sustainable Carolina in recent years, Sebastian’s goal for the program has been to emphasize the importance of taking a whole-system approach to sustainability that accounts for the interactions between environmental hazards and their mitigation strategies.  

“How do you mitigate a hazard without exacerbating another one? Sustainability isn’t just about balancing out resources, it’s also about balancing our resources in a very rapidly changing environment,” said Sebastian.  

For STFS students accustomed to a more traditional approach to urban planning, this reframe proved to be an extremely helpful reminder of how interconnected both the built and natural environments around us are.  

“Initially a lot of us were like ‘oh this is going to be an urban planning field site,’ but I really enjoyed how it was more focused on climate resiliency and doing research that was more on heat islands or tree canopy because it provided a completely different perspective for me of what urban planning can be, especially for something as unknown as the climate changing and the different factors affecting cities like sea level rise or urban heat islands. I think being able to go out and do that research was really insightful for how planning needs to be approached in the coming years,” said Hargrove. 

For their capstone research project, STFS students investigated the roles that tree canopy cover and placement play in mitigating heat vulnerability on campus. 

With the guidance of Sebastian, STFS students mapped the aerial temperatures of certain walking routes on campus, used satellite imaging to more precisely map campus tree cover and combined these data with existing geospatial data using the modeling program R to create a heat model, which identified the most heat-vulnerable areas on campus. While the students were not able to collect data during the hottest parts of the year or even the hottest parts of the spring semester, their findings still show that tree canopy cover, especially that of larger mature trees, is protective against heat and the Urban Heat Island Effect. 

In order to share their research with the public, STFS students created a website, which summarizes their capstone project and the necessary context for understanding their work. On this website, viewers can find easy-to-understand explanations of concepts such as the Urban Heat Island Effect, the role that trees play in mitigating heat, health impacts of heat, environmental justice, the cohort’s research methods and their policy recommendations for UNC. 

Students work to create a heat model with R Code.

As part of their research, students learned about urban heat islands in the context of environmental justice. While environmental hazards like heat may be unpleasant for everyone, they disproportionately impact the health and livelihoods of marginalized groups including low-income and Black, Indigenous, and People of Color (BIPOC) communities.   

With this information in mind, students were prompted to think about which logistic and socioeconomic factors may influence who is most exposed to heat while commuting to, living on, studying at or working on UNC’s campus.  

“I’d personally like to see the course continue to research how climate changes such as Urban Heat Islands affect communities. Our research is not mutually exclusive to climate science alone and should take into account the intrinsic impacts populations face because of these changes,” said Lacayo, who served as the 2023-24 Environmental and Climate Justice Chair of the UNC National Association for the Advancement of Colored People. 

Although these questions were out of their research scope, the 2024 cohort hopes that future STFS students will build upon their work by further investigating the nuances of heat exposure on campus and helping the university implement mitigation strategies that are both sustainable and equitable. 

“We talked a lot in the class this semester about who might be experiencing extreme or prolonged heat exposure on campus, but we didn’t really get to answer that question. I think we did a good job of mapping where the hazards might be, but what we haven’t done, and where the research could still go, is trying to understand who is being exposed to these hotter temperatures on campus,” said Sebastian.  

 At UNC’s 2024 Undergraduate Research Symposium, STFS students presented their capstone research in a presentation titled Cooling the Campus: Understanding Urban Heat Islands at UNC and Harnessing Tree Canopy for Effective Mitigation. Their recommendations for the University emphasized the importance of strategically expanding tree cover in the hottest parts of campus, using heat-mitigation technologies in new and existing buildings and looking to the cohort’s heat model when considering the role of UNC’s heritage trees as they begin to die of old age or disease. With these recommendations, STFS students hope that the university can proactively plan for a more heat-resilient and environmentally friendly campus.  

Left to right: Sara Boburka, Julia Swanner, Laine Cammack, Claire Hargrove, Marie Roche and Krystal Lacayo pose in front of their poster at UNC’s 2024 Undergraduate Research Symposium

When reflecting on their experiences at the field site, Hargrove and Lacayo both spoke about the academic and intellectual growth they experienced at STFS, and strongly recommend the field site to any students who are interested in how people interact with and are impacted by the environment.  

 “I hadn’t had a lot of experience as an urban planning-focused person with actual research, and so I thought it was really awesome and very enlightening, it really got me excited to do more research,” said Hargrove, who plans to pursue a career in the urban planning space. 

 Lacayo, who tentatively plans to pursue a career in environmental law, said that she thoroughly enjoyed her time at STFS. Lacayo urges all students, but especially BIPOC-identifying students like herself who rarely see themselves in environmental spaces, to enroll in a field site like STFS. 

 “I highly, highly encourage them to feel safe and feel brave, take that opportunity to join a field site such as this, because the knowledge that you get, and even the knowledge that you don’t get, and you see the areas that need to be picked up on, everything that you learn, and everything that you don’t learn, it’s definitely something that you will be grateful for. Be open to growth, be open to new challenges.” 

Story by Erin M. Flanagan

 Erin is a rising junior from Carrboro, N.C., majoring in environmental studies at UNC-Chapel Hill. Erin is interested in how systems of oppression fuel both social inequity and environmental degradation and how various social justice movements can promote inclusive sustainability interventions. Before joining the Institute for the Environment as a communications intern, Erin served as the vice president of diversity, equity, and inclusion for UNC-Chapel Hill’s undergraduate urban planning club, BuildUP. 