HOURS OF SAFETY IN COLD WEATHER: A FRAMEWORK FOR CONSIDERING RESILIENCE IN BUILDING ENVELOPE DESIGN AND CONSTRUCTION

This insight brief introduces 'hours of safety' as a metric to quantify how long a building envelope can maintain safe indoor temperatures during power outages in extreme cold. Using simulations of five building types in Duluth, Minnesota, the research demonstrates that high-performance envelopes, such as those meeting Passive House standards, significantly extend the time residents can safely shelter in place compared to older or code-compliant homes.

• The 'hours of safety' framework is designed to quantify the duration a home can maintain comfort and safety thresholds before indoor temperatures reach unsafe levels, which is critical for protecting vulnerable populations during increasing extreme weather events.
• Simulations of power outages during cold snaps reveal a stark difference in resilience based on building age and standards: homes built before 1950 fell below 40°F within 8 hours, while 2009 code-compliant buildings lasted 45 hours before reaching the same temperature.
• High-performance building envelopes provide the highest level of resilience; net-zero energy ready (NZER) homes and Passive House (PH) buildings maintained safe indoor temperatures for over six days (specifically 61 and 152 hours respectively) before falling below 40°F.
• There is a significant equity concern regarding building resilience, as low-income residents and seniors are more likely to live in older housing that can reach life-threatening temperatures within 12 hours of a winter storm-triggered outage.
• Passive House models showed a 90 percent reduction in severe cold stress hours compared to 1950s models and performed over 7 percent better than net-zero energy ready buildings.
• The 'hours of safety' metric could be integrated into public policy and industry practices through residential energy disclosure policies, emergency response planning to identify vulnerable neighborhoods, and future building code developments for new construction and rental properties.

APA

Ayyagari, S., Gartman, M., & Corvidae, J. (2020). HOURS OF SAFETY IN COLD WEATHER: A FRAMEWORK FOR CONSIDERING RESILIENCE IN BUILDING ENVELOPE DESIGN AND CONSTRUCTION. RMI. https://rmi.org/wp-content/uploads/2020/02/Hours-of-Safety-insight-brief.pdf

Chicago

Ayyagari, Sneha, Michael Gartman, and Jacob Corvidae. HOURS OF SAFETY IN COLD WEATHER: A FRAMEWORK FOR CONSIDERING RESILIENCE IN BUILDING ENVELOPE DESIGN AND CONSTRUCTION. RMI, 2020. https://rmi.org/wp-content/uploads/2020/02/Hours-of-Safety-insight-brief.pdf.

Wikipedia

{{cite report |last1=Ayyagari |first1=Sneha |last2=Gartman |first2=Michael |last3=Corvidae |first3=Jacob |title=HOURS OF SAFETY IN COLD WEATHER: A FRAMEWORK FOR CONSIDERING RESILIENCE IN BUILDING ENVELOPE DESIGN AND CONSTRUCTION |publisher=RMI |date=February 2020 |url=https://rmi.org/wp-content/uploads/2020/02/Hours-of-Safety-insight-brief.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{ayyagari2020hours, author = {Ayyagari, Sneha and Gartman, Michael and Corvidae, Jacob}, title = {{HOURS OF SAFETY IN COLD WEATHER: A FRAMEWORK FOR CONSIDERING RESILIENCE IN BUILDING ENVELOPE DESIGN AND CONSTRUCTION}}, institution = {RMI}, year = {2020}, month = feb, url = {https://rmi.org/wp-content/uploads/2020/02/Hours-of-Safety-insight-brief.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }