When a 110°F heatwave collides with a multi-day power outage in Austin, a new University of Texas study says most single-family homes do not just get uncomfortably warm, they get dangerous. The modeling shows older residents are at the highest risk: roughly 85% of detached homes would pose a significant risk of death to an elderly occupant in that scenario, while the current risk for younger people is far lower but rises sharply under future warming.
How the team tested homes
According to the paper in Building and Environment, researchers used a Monte Carlo framework that paired nationally representative ResStock building archetypes with local property records and then simulated a three-day extreme-heat event plus a coincident grid blackout to calculate indoor temperatures and survivability. The setup matched more than 213,000 single-family records to 717 building models and estimated how quickly indoor conditions would cross physiological danger thresholds after HVAC loss.
Major findings
As outlined by UT Austin, the study finds that under contemporary extreme-heat plus blackout conditions, roughly 85% of Austin’s single-family homes expose an elderly occupant to at least 20% heat-risk, a level the authors associate with meaningful mortality risk, while about 15% of homes currently reach comparable risk levels for younger residents. In future climate scenarios, those shares climb substantially, elderly vulnerability approaches near-universal levels, and risk for younger populations rises into the majority of homes.
Which neighborhoods are hardest hit
City-scale vulnerability maps point to central and parts of East Austin as hotspots where homes heat up fastest once the air conditioning cuts off. Phys.org and the study highlight Rundberg and St. John among the neighborhoods with the highest median indoor heat risk, where housing vintages and lot patterns let heat build more quickly indoors when AC fails.
Building age and construction drive risk
The paper shows indoor heat response depends heavily on building attributes such as window quality, insulation, foundation, and roof type, so two adjacent houses can have very different survivability after a blackout. Using the ResStock archetypes, the team demonstrated that older, leakier homes with single-pane windows and light construction generally cross dangerous thresholds far faster than well-insulated, modern buildings, according to Building and Environment.
City can use maps to target help
“This allows us to know what’s actually happening within the neighborhoods, and who’s most vulnerable, without having to go door-to-door,” Marc Coudert, climate resilience and adaptation manager for Austin Climate Action & Resilience, told UT Austin. City staff and the researchers say the building-level output can help prioritize cooling centers, weatherization programs, and where to pilot solar+battery backups to reduce the deadliest exposures.
What residents can do
The City of Austin maintains a list of Cooling Centers and heat-safety guidance and points residents to outage resources for the summer months; the city’s Heat Awareness page lists current locations and tips. Local coverage from KVUE summarized the research for viewers on Feb. 10 and reminded Austinites to check on older neighbors, know where nearby libraries and rec centers operate as cooling sites, and sign up for outage alerts through Austin Energy.
Why the study matters beyond Austin
The authors say the methodology is scalable and could be applied to other U.S. cities to convert building-level vulnerability into actionable maps for planners and emergency managers. As noted in a university release carried on networks such as EurekAlert!, the open, building-level approach is intended to help cities prioritize retrofits and targeted resilience investments ahead of hotter summers.
