Eric Kaiser sits down with Haley Harlow and Al Mitchell from PHIUS (Passive House Institute US) to explore Revive 2024, a groundbreaking new retrofit standard focused on thermal resilience and healthier, safer existing buildings. Haley shares her path from Pennsylvania College of Technology to her current role managing building certifications at PHIUS. At the same time, Al recounts his journey from aspiring car engineer to building scientist, drawn to the elegant complexity of whole-building systems.

Together, they unpack how Revive differs from traditional PHIUS new-construction standards. Instead of focusing on heating and cooling load targets, Revive emphasizes thermal resilience—a building's ability to remain habitable for up to a week during power outages or extreme weather. They also discuss ReviveCalc, PHIUS's new software tool for analyzing retrofit scenarios, allowing designers to test various upgrade packages, balance cost and performance, and phase improvements over time. The tool incorporates lifecycle cost analysis, dynamic energy modeling, and resilience metrics, making advanced design decisions more accessible to real-world projects.

Both guests share their excitement about addressing the massive stock of underperforming existing buildings. Haley connects it to her own experience growing up in energy-intensive apartments, while Al reflects on how to use today's computing power better to design resilient, efficient homes. They close with a shared message: retrofitting our current buildings is not only possible, it's essential for the future of sustainability, comfort, and community resilience.

Key Takeaways

• PHIUS Revive 2024 focuses on retrofits, bringing resilience and energy equity to the existing building stock.

• Thermal resilience replaces traditional load metrics, ensuring buildings remain habitable during grid or system failures.

• ReviveCalc helps users model envelope and mechanical upgrades, estimate lifecycle costs, and optimize phase-by-phase improvements.

• The program aligns with ASHRAE Guideline 0.2 for commissioning and integrates EPA's Energy Savings Plus Health framework.

• Air sealing remains the top "bang for the buck" retrofit measure for both comfort and energy savings.

• CPHC certification (Certified PHIUS Consultant) is open to anyone—no degree required.

• The Revive approach balances performance, cost, and practicality for real-world projects.

Haley's LinkedIn: https://www.linkedin.com/in/haley-harlow-3965b41b5

Al's LinkedIn: https://www.linkedin.com/in/al-mitchell-bb74827b/

Info on Phius Revive 2024: https://www.phius.org/phius-revive-2024

This episode was recorded in October 2025.