This book provides a compelling and timely exploration of passive design strategies in the coastal city of Bushehr, revealing how centuries-old architectural wisdom can inform today?s urgent sustainability agenda. Set against the backdrop of escalating global warming and the high energy demand of HVAC systems, it demonstrates how vernacular solutions can significantly enhance building performance in hot?humid climates. Drawing from Bushehr?s rich architectural heritage, the book showcases climate-responsive orientation, spatial organization, natural ventilation methods, and innovative shading systems that ensured thermal comfort long before mechanical cooling existed. Combining field observations, environmental measurements, and insights from traditional building owners, it illustrates how these proven techniques can be refined through modern engineering analysis and seamlessly integrated into contemporary construction. Written for architects, engineers, students, and urban planners, this book serves as both a vital documentation of cultural heritage and a practical roadmap for designing energy-efficient, climate-adaptive, and culturally grounded buildings in coastal and hot and humid regions worldwide.