As heatwaves increase in severity, urban areas are exploring ways to keep their neighborhoods cooler. Researchers from The University of Texas at Austin have created a new tool that has already pinpointed possible solutions for Houston, a city where the effects of heat can differ greatly among various communities.Researchers Kwun Yip Fung, Zong-Liang Yang, and Dev Niyogi from the UT Jackson School of Geosciences, along with their collaborators from Spain and Canada, have developed a new computer modeling framework that combines factors related to human comfort and social vulnerability with strategies for mitigating heat islands, alongside an advanced urban climate modeling system.

Their findings were published in PNAS Nexus.

In their study focused on Houston, the researchers found that trees offered greater cooling benefits compared to roof treatments in the most heat-prone areas. The assessment of vulnerability takes into account various sensitivity factors.

Various elements, including income levels, family makeup, and minority group status, along with factors related to adaptability like the type of housing and transportation availability.

Urban heat islands form in cities where man-made structures like buildings and roads retain more heat from sunlight compared to natural areas like forests and lawns. This excess heat results in higher energy use for air conditioning, increased pollution due to greater electricity consumption, and can negatively affect people’s health and comfort. The intensity of this heat island effect can differ across various parts of a city, resulting in varying impacts.

Many individuals are aware of wind chill indices

used in winter to explain how cold weather and wind combine to make people feel colder. In a similar manner, the heat index takes into account both temperature and humidity to illustrate how these factors can increase discomfort due to heat. Prior to this research, there had been limited studies quantitatively evaluating the impact of direct sunlight on individuals in urban environments.

“There is a significant difference in comfort levels for construction workers who are exposed to direct sunlight compared to those working under the shade of trees,” mentioned Yang.

The universal thermal comfort index integrates human comfort based on temperature and humidity…

Researchers explored various ways to reduce heat in urban areas. They suggested that their findings could be applicable across different communities.

The study examined three main approaches to combat the heat island effect: applying white paint on roofs to boost solar reflection, installing vegetation on rooftops to enhance moisture evaporation through plants, and increasing tree planting for added shade and evaporation. In a typical city block, painting roofs white showed the most significant reduction in temperature during daytime hours.

However, when analyzing specific neighborhoods within Houston, the outcomes revealed more complex patterns.

The U.S. Centers for Disease Control and Prevention

has created a social vulnerability index to assess how different neighborhoods are affected by socioeconomic elements and their ability to adapt. By classifying Houston’s neighborhoods based on this vulnerability index and utilizing the human comfort index, it was found that while white roofs are the most effective cooling method in low-vulnerability areas, planting trees is a more effective strategy in areas with higher vulnerabilities.

“With our cooling index and vulnerability data now established, we can merge them to identify which methods offer greater cooling benefits for those at risk.

Study Highlights the Importance of Planting Trees in Vulnerable Neighborhoods

According to the lead researcher, Fung, who carried out this study as part of his doctoral work at the Jackson School, there are significant findings regarding urban green spaces.

The study found that areas with higher vulnerabilities also tended to have more available land for planting trees, indicating a greater opportunity to increase greenery. However, these neighborhoods had less roof space suitable for either painting white or installing vegetation.

“Having identified that vulnerable neighborhoods possess ample space for tree planting, we should focus on introducing trees in these locations,” Fung emphasized. “Conversely, in less vulnerable areas, we should concentrate on alternative methods like cool roofing.”

Applying this approach to different cities may involve additional factors. For instance, in dry regions like Arizona, it’s crucial to choose tree species that can withstand heat and drought conditions. In colder cities, the absence of air conditioning affects communities that are at higher risk during heatwaves.

This new framework could lead to innovative strategies that integrate both rooftop solutions and tree planting, along with other methods like reflective pavement surfaces.

“We view this as a starting point; we continue to investigate further,” remarked Fung. “With the creation of the index and methodology, they can now be expanded upon.