Improving urban thermal risk models by burning in building details

Scientists at the Department of Energy’s Oak Ridge National Laboratory have developed the first urban heat wave simulation to account for the combined effects of infrastructure construction. This method can better understand the impact of excess heat on at-risk populations and guide local planners in seeking mitigation strategies.

Heat kills more people than any other extreme weather event. Heatwaves are getting hotter and longer, setting enviable new records in densely populated cities. Las Vegas, Nevada, hit an all-time high of 120 degrees Fahrenheit on July 7, marking seven consecutive days with highs of 115 degrees Fahrenheit or higher. According to the National Oceanic and Atmospheric Administration, June through August 2024 was the hottest summer on record in the Northern Hemisphere, at 2.74 degrees Fahrenheit above average.

Compounding the effects of rising temperatures in cities is the presence and design of building infrastructure. Buildings can influence wind speed and direction, absorb solar radiation, and reduce heat transfer from the system. Representing these details is critical for accurate simulation to guide decision making.

“There’s a lot of heat being shared between buildings, which is beneficial in the winter, but in the summer when that much heat is trapped in a neighborhood, it can amplify heat waves,” said ORNL’s Melissa Dumas. There is,” he said. Led the modeling work. “If those buildings aren’t represented in the model, you can’t understand what that amplification is and how it exacerbates the urban heat island.”

The scientists tested their approach by modeling the July 2010 heatwave in Washington, D.C., when temperatures reached a high of 102 degrees.

As they describe in the magazine NPJ Urban Sustainability, adding details about the presence, proximity, structure, and design of buildings significantly improves the modeling of temperature, relative humidity, and heat flux across cities. I found that it can be improved.

The results showed that including building data allows for more accurate simulations, especially for the most at-risk areas of the city. Scientists have found that simulations that don’t build data err on the cold side.

“We found that neighborhoods with the lowest average incomes were the most adversely affected by the heat wave, something we would not have been able to determine without this building data,” Dumas said. Building detail levels ranged from 10 meters to 100 meters to 1 kilometer, covering the entire study area and providing a 3D representation of the thermal effects from the structure.

“The information provided by this resolution will allow for the first time a quantitative analysis of the effects of excess heat on specific regions,” Dumas said. “The result is a climate model that includes all weather processes and also allows us to examine the interplay between how buildings are placed and their impact on the people who live in them.”

“When constructing a new neighborhood, even before thinking about HVAC, knowing the height, placement, and footprint of buildings that will result in an energy-efficient system is something city planners can use as informed by models that include these parameters. It’s an important element that can be collected and incorporated into planning decisions,” Dumas said.

Scientists have created an open-source tool that allows users to generate custom models using local data. This software is described in detail in the Journal of Open Source Software.

Other scientists involved in the project include Joshua New at ORNL and Brett Bass, now at Procter & Gamble. Levi Sweet-Breu, currently at Baylor University. Christa Brelsford, currently at Los Alamos National Laboratory. and Linying Wang of Boston University.