In recent years, the most devastating climate events have not always been the most dramatic. While hurricanes and wildfires capture headlines, extreme heat has emerged as the most pervasive and deadly climate hazard of our time. The past decade has brought record-breaking global temperatures, with 2023 and 2024 each surpassing previous highs. Nighttime temperatures now often fail to cool sufficiently, leaving bodies, buildings, and infrastructure under sustained stress.
A recent study conducted by Bora Architects and published in AIA Architect, Home is Where Resiliency Is, underscores that thermal safety, the ability of a home, apartment or other building to maintain safe indoor conditions during extreme heat or cold, is essential for protecting health, equity, and continuity or operations. Yet many buildings, particularly older ones or those reliant solely on mechanical cooling, are ill-prepared for extended heat events or power outages.
For architects, this reality poses an urgent challenge and an opportunity. Whether designing new projects or retrofitting existing buildings, the profession has both the responsibility and the tools to protect communities from the mounting risks of heat.
Public Health
Heat is now the leading cause of weather-related deaths in the U.S. Unlike sudden disasters, it builds silently, affecting older adults, children, outdoor workers, and households without reliable air conditioning most severely. Indoor spaces quickly become unsafe when cooling fails, a risk magnified by grid stress during peak demand.
Households without mechanical cooling or those unable to afford higher energy bills are disproportionately vulnerable. As climate change drives more frequent and longer heatwaves, architects must plan for scenarios where conventional cooling is not always available.
Infrastructure and Grid Reliability
Heatwaves often coincide with droughts or wildfires, both of which can further destabilize the energy grid. Power companies may preemptively de-energize transmission lines during wildfire risk, or plants may go offline due to cooling water shortages. Without resilient building strategies, blackouts in extreme heat can create life-threatening indoor conditions within hours.
Economic and Social Impacts
Heat affects productivity, increases building operating costs, and exacerbates inequities. Communities lacking shade, green infrastructure, or efficient buildings shoulder higher health risks and utility burdens. Resilient design must therefore be both a climate adaptation measure and an equity intervention.
Passive Survivability and Thermal Safety
The resilient design community has long discussed passive survivability, comprehensive passive strategies for buildings to keep occupants safe and help a building minimally functional for several days during a power outage. Today, the more fundamental concept of thermal safety, focuses on maintaining safe indoor temperatures during a power outage coupled extreme conditions using enhanced thermal enclosures, window shading, and potential for passive night flushing.
This principle is now embedded in rating systems such as LEED v5's Resilient Spaces credit, which encourages projects to designate and design safe zones that remain habitable even during blackouts. For architects, this means shifting from only designing for comfort under normal operations to also designing for safety under stress.
Design Strategies for Thermal Resilience
1. Building Envelope
- High-reflectivity roofs and walls: Materials and coatings that reflect solar radiation reduce heat gain and extend safe indoor conditions.
- Continuous insulation and thermal bridging reduction: Critical for both new construction and retrofits, ensuring heat stays out and coolness remains in.
- Exterior shading: Overhangs, louvers, fins, and brise-soleil systems are essential for south- and west-facing façades, cutting peak solar gain.
- Operable windows and natural ventilation: When outdoor conditions allow, these provide passive cooling and purge accumulated indoor heat.
2. Building Systems
- Renewables and storage: On-site photovoltaics paired with batteries can sustain ventilation fans, critical lighting, or mini-split heat pumps in thermal refuge areas during outages. This supports active survivability and extends the benefits of design for thermal safety.
- Efficient cooling systems: High-performance HVAC reduces both operational costs and grid stress during peak demand.
- Smart controls: Sensors and automation can optimize shading, ventilation, and cooling, responding dynamically to conditions.
3. Thermal Refuge Spaces
- Designated safe rooms: Incorporate highly insulated, shaded, and ventilated areas within homes or community facilities where conditions can remain tolerable during extended outages.
- Resilience zones: For multifamily or institutional projects, create zones that can be prioritized for backup power.
4. Site and Landscape Design
- Shade trees: A proven, low-tech intervention that can reduce surrounding air temperatures by several degrees.
- PV parking canopies and shade structures: Provide dual benefits, reducing heat islands and generating renewable energy.
- Cool pavements: Emerging reflective surface technologies can lower surface temperatures and support neighborhood cooling, though glare and reflectivity trade-offs must be managed.
Existing Building Retrofit Opportunities
While new projects allow architects to fully integrate resilience strategies, retrofitting existing buildings is where the greatest opportunity lies. Much of the building stock that will be in use mid-century is already built. Key retrofit interventions include:
- Adding roof reflectivity through coatings or cool membranes.
- Installing exterior shading devices or window films.
- Upgrading insulation and sealing air leaks.
- Retrofitting with operable windows where feasible.
- Creating backup power-ready circuits in critical areas.
- Planting trees or adding shading at key exposures.
Even modest interventions can extend the survivability of a building during extreme heat, buying time for occupants during outages and reducing reliance on air conditioning during normal operations.
Innovations in Materials and Research
Some recent research may provide viable new solutions in the near future to help make sites and buildings more thermally resilient:
- Radiative cooling paints: Purdue University's "super-white" acrylic reflects over 98% of solar radiation and cools surfaces below ambient air temperatures. This could become transformative for retrofits and new construction alike.
- Phase-change materials: Integrated into wall or ceiling materials, these can absorb and release heat, smoothing temperature fluctuations.
While not yet mainstream, these innovations point to a future where material science expands the palette of resilience strategies available to architects.
Equity and Community Preparedness
Resilience and equity are inseparable. Vulnerable households, often renters, low-income families, and historically marginalized communities, are more likely to live in underperforming buildings and least able to afford retrofits or higher energy bills.
Architects have a role in addressing this imbalance. Designing schools, libraries, and community centers as neighborhood resilience hubs ensures that safe spaces are available to all during heat emergencies. Integrating equity into resilience design is not just socially responsible; it strengthens the fabric of entire communities.
What Architects Should Do Now
Preparedness Month is an opportunity for architects to reflect on how design can save lives during climate-driven events. Key actions include:
- Integrate thermal safety into early design goals: Treat it as essential as fire safety or structural stability.
- Educate clients: Frame resilience not only as risk mitigation but also as value creation, reducing operating costs, protecting occupants, and future-proofing investments.
- Leverage rating systems: Use LEED, WELL, or local resilience codes to guide and benchmark thermal safety performance.
- Collaborate across disciplines: Work with engineers, landscape architects, and public health experts to design holistic resilience strategies.
- Advocate for equity: Prioritize designs that protect vulnerable occupants and serve broader community resilience.
Extreme heat is no longer a distant projection, it is the defining climate challenge of this century. For architects, designing for thermal resilience is not optional, it is an ethical and professional imperative.
By embedding thermal safety into every project, through high-performance enclosures, shading, operable windows, renewable energy, and thoughtful retrofits, we can help clients prepare for escalating heat risks. More importantly, we can ensure that buildings remain safe havens when communities need them most.
Preparedness Month reminds us that resilience begins long before a disaster strikes. Every project designed or retrofitted today will better face tomorrow's hotter climate. The choices we make now will determine whether our built environment protects or imperils the people who depend on it.
Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect and consultant with over 36 years of experience in sustainable building design. He is Director of Sustainability with Intertek Building Science Solutions in Portland, OR.
------------------------------
Alan Scott FAIA
Intertek, Building Science Solutions
Portland OR
------------------------------