UT Austin study maps indoor heat danger for every Austin home during heatwave blackouts

Citywide modeling finds indoor conditions can become life-threatening when air conditioning fails

A new University of Texas at Austin-led analysis warns that power outages during extreme heat can turn large portions of Austin’s housing stock into dangerous environments, particularly for older adults. The research is presented as the first citywide, home-by-home assessment of indoor heat vulnerability across an entire city’s single-family residences, using Austin as the test case.

Researchers modeled what would happen if a multi-day heat wave coincided with a grid blackout that disables air conditioning. Under current conditions, the study estimates that 85% of Austin’s single-family homes would present a significant risk of death for an elderly person who remains inside during such an event. For younger residents, the estimated share of homes presenting significant risk is far lower at roughly 15%.

How the researchers built a home-level risk map for Austin

The team matched 213,626 single-family homes to a set of building-energy models using property characteristics such as construction year, size, floors, foundation and roof type, and window quantity and quality. The work combined local property records with a national housing dataset used for building-performance simulation, then estimated indoor heat exposure during a historical, three-day extreme heat event in Austin with outdoor temperatures above 110°F, layered with a simulated blackout.

The results emphasize that outdoor temperature alone does not reliably indicate indoor danger during an outage. Building-specific attributes can slow or accelerate indoor heat buildup, meaning two houses on the same block may present very different levels of risk when cooling systems fail.

Neighborhood patterns and who faces the highest danger

The analysis identifies uneven geographic risk across Austin. Neighborhoods including Rundberg and St. John emerge as among the most vulnerable overall in the modeled scenarios. The study’s neighborhood-scale summaries are intended to help prioritize where interventions could have the greatest impact during emergency planning and longer-term resilience work.

Implications for Austin’s emergency response and heat resilience planning

Austin already designates public facilities such as library branches and recreation centers as cooling centers during summer heat, offering temporary relief during normal operating hours; service animals are permitted at city facilities. The study’s authors and city collaborators describe the home-level modeling as a way to target mitigation efforts more precisely without relying on door-to-door assessments.

• Heat-risk mapping to guide neighborhood-level preparedness and outreach
• Expanded access to cooling locations and transportation options during declared heat emergencies
• Home-focused upgrades such as weatherization and other measures aimed at reducing indoor heat buildup

The central finding is that indoor heat can become a primary hazard during compound events: extreme temperatures combined with loss of power that disables mechanical cooling.

The paper also examines future conditions under warming scenarios, projecting a substantial expansion of risk. The researchers report that additional temperature increases could shift risk for younger populations sharply upward, underscoring the importance of integrating indoor heat survivability into planning for both infrastructure reliability and public health.