Exposure to low indoor air temperature is a major contributor to temperature-related mortality during extreme cold events

especially when power outages disrupt operation of space heating systems. This study explores the impact of high-performance windows on the thermal resilience of residential buildings during extreme cold weather and grid power outages

as well as their long-term benefits through energy efficiency and reduced risk of property damage. Building performance simulations were conducted for reference residential buildings in three construction vintages and two major U.S. cities located in cold climate zones

considering two types of extreme cold events: short and severe

and long and milder. Our research found that even houses compliant with current energy codes struggle to maintain safe indoor temperatures for more than a few hours during power outages

necessitating rapid evacuations. High-performance windows can extend the thermal survivability time by up to 3.8 days within a 7-day cold snap and significantly reduce risk of bursting frozen water pipes

depending on the building’s insulation and infiltration level

cold event severity

and occupant vulnerability. This extended thermal safety time is crucial in scenarios where reduced mobility complicates emergency responses in senior housing. In addition to boosting thermal resilience

upgrading older homes with high-performance windows can reduce heating energy consumption by over 18 % and cooling energy by 15 %. Our findings highlight the need to incorporate thermal resilience assessments into new designs or major retrofits

including the use of typical and extreme weather scenarios and advanced technologies like high-performance windows.