As urban environments grow denser and surface space becomes increasingly limited, the development of underground structures-ranging from transportation tunnels and parking basements to advanced data centers-has become not only common but essential. However, these subterranean spaces present unique challenges when it comes to environmental control, human comfort, and equipment safety.

The purpose of this book is to provide a comprehensive overview of HVAC design, ventilation strategies, and climate control techniques tailored specifically for underground environments. Unlike above-ground buildings, underground structures face distinct constraints, such as limited access to natural ventilation, elevated humidity risks, and complex smoke management scenarios during emergencies. These conditions require engineers, designers, and facility managers to apply specialized knowledge and innovative solutions.

Drawing upon decades of field experience and global case studies, this book serves as both a technical reference and a practical guide. It explores the fundamentals of airflow design, equipment selection, environmental monitoring, and energy efficiency in underground settings. Special attention is given to applications like tunnels, basements, and underground data centers, where precise environmental control is critical to occupant safety and system reliability.

Whether you're an HVAC engineer, a building services consultant, or a project manager involved in underground developments, this book aims to equip you with the insights and tools necessary to design and maintain safe, efficient, and resilient HVAC systems in below-grade environments.

I hope this work contributes meaningfully to your practice and fosters better understanding and innovation in one of the most demanding areas of building services engineering.