Researchers pilot potentially life-saving heat alert app
October 23, 2025
AMES, Iowa – As extreme heat continues to be the leading cause of U.S. weather-related deaths – more than floods, tornadoes and hurricanes – researchers at Iowa State have developed a personalized mobile app that alerts users when their home is at risk of overheating.
Over the summer, a collaborative team of student and faculty researchers performed a pilot study of the app, CommHEAT, with a group of residents from inner city neighborhoods in Des Moines. Over half of the homes in these neighborhoods do not have central air conditioning and many do not have air conditioning at all.
“As far as we know, this localized and personalized heat emergency prediction is not available elsewhere yet,” said Ulrike Passe, architecture professor and director of the Center for Building Energy Research at Iowa State. Passe leads the project with a team of faculty who have worked with her on a variety of related projects.
With a three-year, $1.2 million U.S. National Science Foundation grant, the project began in 2023 with outreach to local communities, data collection and the creation of large databases to house thermal simulations based on 3D digital models. This past summer, researchers tested the app with volunteer residents and are currently analyzing those results, including participant feedback and prediction accuracy.
“The ideal scenario would be that in the future, a refined version of the app would be widely available for communities to implement in their community’s heat emergency plans,” Passe said.
During the summer, heat indexes reached up to 115 degrees in Iowa, and Des Moines experienced its 11th consecutive hotter-than-average summer. Some of the study’s participants reside in the East Capitol neighborhood of Des Moines, one of many urban areas susceptible to the urban heat island effect, where hot temperatures can become trapped in heat-absorbing buildings, leading to prolonged unsafe temperatures.
Known as a silent killer, extreme heat can linger in these buildings overnight even when outdoor temperatures typically cool off. This poses a particularly severe threat to older adults, young children and individuals with medical conditions.
Passe said the project was sparked by a question posed by a Polk County health official in 2016 during discussions on a previous research project with the city of Des Moines.
“They wanted help identifying which buildings were most vulnerable to heat. We are answering those questions using real-time machine learning,” Passe said.
Connecting with the community
Meeting the needs of the most vulnerable residents is a priority for the CommHEAT project. Tian Yao, an Iowa State human computer interaction doctoral student, led efforts to connect with residents of multiple inner-city neighborhoods of Des Moines to assess their needs regarding heat inside their homes.
She immersed herself in the neighborhoods, spending time with residents to build trust and gain a genuine understanding of the challenges they face during heatwaves. She attended neighborhood association meetings, visited local stores to have meaningful conversations about the project and surveys to about 1000 residents – all to ensure the research reflected the real needs and lived experiences of the community.
“It’s hard because people who don’t have air conditioning might also have three jobs to make ends meet,” Yao explained. “These are challenging people to reach.”
Fifteen qualifying volunteers were chosen and had sensors installed in each of their homes. During heat events from May through mid-October, participants responded to brief surveys, sent twice daily via text message, asking about their perceptions and behaviors. A heat event was defined as a time period during which the heat index was predicted to exceed 100 degrees for three or more consecutive days.
The research team is now analyzing feedback from participants on their perceptions, adaptive behaviors and social network support.
The project also involved a collaboration with two local middle school teachers, Connie Simonsen and Macey Smith, whose related work throughout the three-year project was funded through a National Science Foundation Research Experiences for Teachers (RET) program supplement.
Simonsen and Smith were science teachers at Harding Middle School in the Highland Park neighborhood of Des Moines, one of the areas with study participants. To engage the local students, a weather station was installed at the school where the teachers helped students monitor the weather and gather data used in the study. The engaging lessons turned into a full curriculum and culminated with a project with the city of Des Moines and a Design Jam event where students competed in groups to solve real-world problems.
“This experience helped us learn not just what scientists study, but how they think, communicate and generate knowledge. We are excited to implement what we’ve learned and created to enhance learning for our students in a hands-on and inquiry-driven way,” Simonsen said.
Both Simonsen and Smith are now teaching science in the Ankeny Community School District, where they will continue to implement this work into their classrooms.
A data-driven process
Using the extensive data collected from the participants’ homes, Iowa State doctoral mechanical engineering students Vishal Muralidharan and James Afful, led by Professor Baskar Ganapathysubramanian, along with architecture students Kimia Sharifi and Angela Jones, created the 3D thermal models assigned to each participant’s home.
The digital models represent archetypes based on previous years’ data collection, complete with unique characteristics such as orientation, construction materials, nearby trees, roads, concrete pavements and other outdoor factors that impact indoor temperatures.
Outdoor weather conditions collected from weather stations, Mesonet data and predictions from the National Oceanic and Atmospheric Administration helped identify how much sunlight was hitting the home, what direction the wind was coming from and at what speed, the temperature, humidity levels and more.
“All of these things matter,” said Ganapathysubramanian, the Joseph C. and Elizabeth A. Anderlik Professor in Engineering. “In terms of how much radiation, how much light there is on the windows and the doors and the walls, and how much warm air is hitting the walls. That affects the internal comfort.”
The goal was to go beyond standard factors and account for as many microclimatic factors as possible that could influence the indoor temperature. This would allow researchers to predict with greater accuracy how the home would react to forecasted weather.
To manage and integrate this vast amount of data, a large server was developed by a team with Iowa State’s VRAC Research Center, including Muralidharan; Eliot Winer, professor of mechanical engineering and director of VRAC; and Alex Renner, VRAC research scientist.
“The database is where all the information comes together and then is queried by the phone app, so that it visualizes the data for residents,” Passe said.
Sharifi worked with the VRAC team to create 3D models using data from previous summers. During the study, the team ran daily thermal simulations on each model to see how the predicted weather conditions would impact each participant’s simulated models. The highest temperature she recorded inside a participant’s home was between 90 and 95 degrees Fahrenheit.
“The buildings do warm up like the outdoors if there’s no AC,” she said.
Building the app
Data from the simulations is packaged in a way that is easily consumable by users of the app, a process also led by Yao, who designed the app’s interface to meet the users’ and stakeholders’ needs. The app was programmed by the VRAC team.
The CommHEAT app’s home screen scrolls to show the individual home’s current internal and external conditions as well as the predicted weather conditions. This is where users are alerted if their home is predicted to become unsafe.
The community page then allows users to create a social network by inviting members to their group, where they can communicate and view each other’s predictions to help alert each other in times of emergency. The third page is a localized Google map with nearby cooling centers and other resources.
Project completion will provide communities with a framework for microclimate-informed heat alerts in real time, according to Passe. Outcomes will support local heat and health action plans to reduce emergency calls, heat illness-related hospitalizations and mortality from indoor heat exposure.
A true collaborative effort
While faculty members led the project, it was the students who powered the engine for CommHEAT, Passe said. Students from each of the disciplines formed their own relationships with each other, creating a separate communication channel to stay updated on each other’s progress.
Sharifi, who is set to graduate in December, said the CommHEAT project has been the highlight of her academic career.
“There were so many things I never thought I could learn or do,” she said.
The project has led to several other related projects for her and she’s exploring the possibility of returning to Iowa State for the human computer interaction program that Yao is in, she said.
Yao said she learned how to collaborate with a variety of professors, students and community members with a wide range of backgrounds. While reviewing feedback from the pilot study participants, Yao said they appear to be grateful for the work they are doing and are eager to continue to help.
“It’s very nice to hear and makes me feel like what I’m doing is meaningful,” she said.
Also contributing to the project was a team of social psychologists from the University of Northern Iowa, who interviewed community members and stakeholders, and are working with the team on understanding the theories behind people’s behaviors.
A University of Texas at Arlington professor along with two graduate students are working on an agent-based model to simulate the operation of the app in the community.
The ISU research team
• Ulrike Passe, professor of architecture, project leader
• Michael Dorneich, the Joseph Walkup Professor in Industrial and Manufacturing Systems Engineering, human computer interaction
• Jan Thompson, Morrill Professor of Natural Resource Ecology and Management
• Baskar Ganapathysubramanian, Joseph C. and Elizabeth A. Anderlik Professor in Engineering
• Katherine Richardson Bruna, professor of education
• James Afful, doctoral mechanical engineering student
• Ethan Griesman, senior computer engineering student
• Vishal Muralidharan, doctoral mechanical engineering student
• Kimia Sharifi, graduate architecture student
• Tian Yao, doctoral human computer interaction student
• Angela Jones, senior architecture student
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