As climate change accelerates, the intersecting threats of extreme heat and power outages increasingly challenge urban resilience, especially for vulnerable populations residing indoors. A pioneering study led by researchers at The University of Texas at Austin delivers the first comprehensive assessment of indoor heat risk on a home-by-home basis across an entire metropolitan area. Austin, Texas serves as the testbed for this groundbreaking work, which unveils the stark indoor dangers elderly residents face during heatwaves combined with electricity disruptions.
The investigation’s computational simulations reveal that during a severe, historical three-day heat event exceeding 110°F, concurrent with a blackout, approximately 85% of Austin’s single-family homes impose a lethal risk to elderly occupants remaining indoors. Contrastingly, the risk for younger demographics is markedly lower, with only about 15% of homes presenting significant threat. These findings underscore not only the heightened sensitivity of older adults to heat stress but also the pressing need to consider indoor microclimates and building characteristics when evaluating heat vulnerability.
Traditionally, heat risk assessments leverage outdoor temperature metrics, yet this study reveals that indoor conditions diverge considerably based on building construction, materials, and design. Older homes with single-pane windows and poor insulation heat up rapidly, whereas newer, well-sealed residences delay internal temperature rises. This heterogeneity in indoor thermal response exacerbates the threat landscape amid power outages, wherein air conditioning and ventilation systems fail. The study meticulously matched Austin’s 213,626 single-family homes to 717 prototypical building models, incorporating factors such as construction year, window quality, foundation type, and roof materials using extensive datasets from the U.S. Department of Energy and Travis County Appraisal District.
The methodology involves high-fidelity computational modeling that replicates heat transfer dynamics during sustained heatwaves without active cooling. By integrating climatic data, building physics, and occupant age-related survivability thresholds, the research delineates spatial patterns of indoor heat mortality risk at a granularity previously unattainable. Notably, neighborhoods like Rundberg and St. John emerge as epicenters of vulnerability, where infrastructure disparities compound the peril faced by elderly residents.
This study’s implications resonate beyond Austin. As climate models forecast an increase in the frequency and intensity of heatwaves—predicted to double by 2100 in this region—the compounded risk of blackouts during these events portends a growing public health crisis. Urban planners and policymakers now gain access to a detailed, data-driven map that pinpoints where intervention is most crucial, empowering targeted strategies rather than blanket measures.
Potential mitigation pathways, informed by this nuanced indoor risk landscape, include the strategic deployment of cooling centers, prioritized weatherization programs, and infrastructure upgrades aimed at enhancing thermal resilience in high-risk homes. This approach signals a paradigm shift from perceiving heat risk as a generalized external environmental issue to acknowledging the critical role of indoor environments in survival outcomes during extreme events.
Furthermore, the study underscores the significance of integrating climate resilience efforts into urban planning frameworks. Austin Climate Action & Resilience’s utilization of this model exemplifies how municipal authorities can operationalize scientific insights to improve neighborhood-level adaptation. The ability to identify vulnerable subpopulations without exhaustive door-to-door surveys enhances both efficiency and precision in emergency preparedness.
Heat-related mortality predominantly occurs indoors, a fact historically overshadowed by outdoor temperature analyses. The phenomenon resembles the dangerous effects of trapped heat in enclosed spaces, akin to greenhouse or vehicular heatstroke scenarios. Hence, this research emphasizes the fundamental importance of assessing the thermal inertia and ventilation characteristics specific to individual residences in the context of blackout scenarios.
Professor Dev Niyogi from the UT Jackson School of Geosciences highlights the critical transition in risk framing promoted by this research: moving from broad statements about urban heat to actionable knowledge pinpointing locations and feasible solutions. The fusion of climatology, building science, and demographic modeling in this work reflects a multidisciplinary leap forward in understanding and combating climate-induced hazards.
Graduate student Calvin Lin played a pivotal role in bridging housing stock data with national building archetypes, enabling a realistic representation of Austin’s architectural diversity. This methodological rigor enhances the model’s predictive power and sets a replicable template for other cities facing similar threats globally.
Ultimately, as urban heat intensifies under climate change trajectories, the intersectional vulnerability exposed by this study serves as a clarion call for comprehensive solutions. Addressing indoor heat risks demands collaborative synergy across engineering, public health, urban planning, and social equity domains, underscoring that safeguarding human life under extreme thermal stress requires more than just external cooling—it necessitates transforming the very spaces people call home.
Subject of Research: Indoor heat vulnerability and mortality risk during extreme heatwaves compounded by power outages in single-family homes.
Article Title: From comfort to survival: Indoor heat vulnerability during extreme events
News Publication Date: 1-Feb-2026
Web References:
- University of Texas at Austin press release
- Journal of Building and Environment, DOI: 10.1016/j.buildenv.2025.114070
- UT-City CoLab
- UT-City CoLab Future Climate Projections
Image Credits: Calvin Lin
Keywords: Housing, Computer modeling, Climate change, Climate data, Heat, Heating cooling and ventilation, Building ventilation, Urban planning, Cities, Urban studies, Human geography
