This book provides a comprehensive ovreview of the princples, design installation and maintennace of air conditioning and ventilation systems,The book covers a wide range of topics, including psychrometrics, load calculations, equipment selection ,ducktwork design, air distribution, energy effiency , indoor air quality and system conctrol .It also addresses emerging trends and technologies in the field ,such as smart HVAC systems and sustainable ventilation systems.This book also explores various aspects of HVAC syhstems, which are vital components of building mechanical systems.By providing thermal confort for occupants and maintaining indoor air quality, HVAC systems contribute significantly to the overall functionality and livabilty of buildings.