As we grapple with the climate crisis, experts have projected a need for several million deep energy retrofits on buildings in the U.S. and Canada prior to 2050. Passive House Retrofit Details will equip architects with information critical to understanding and undertaking these complex projects. This book presents 26 case studies of successful retrofit projects in North America, focusing on key technical details and lessons learned during the retrofit process. Projects showcase a range of retrofit strategies for common building types, including urban brownstones, brick rowhouses, wood-frame triple-deckers, multifamily towers, and suburban ranch homes. Case studies from diverse cities and climates, including New York, Boston, Toronto, San Francisco, and Calgary, are examined using full-page illustrations of architectural details, technical descriptions, and narratives exploring the unique concerns and challenges of each project such as constructability, phasing, financing, and preservation. A roundtable discussion with leading practitioners explores the challenges and opportunities of Passive House retrofits and identifies the measures and innovations needed to advance this work at scale. This book will be a crucial resource for architects working on retrofit projects and upper-level students of architecture, construction and building science.