The term Air Handling System' refers to the equipment where air is conditioned to an acceptable level for distribution within the building. An air handling unit often abbreviated as AHU is a very important component of central-air-conditioning system. It is responsible for drawing return air from the indoor spaces, mixing it with outdoor air, conditioning it to the acceptable level for distribution within the building. The modular packaged equipment offered by various manufacturers is pretty standard. HVAC designers can simply spec the performance requirements and pick and choose from a wide array of standard building blocks to assemble a unit that meets their specific project needs. But large majority of air handlers are custom built or tailor made demanding HVAC designer to apply fundament psychrometrics processes to precisely estimate the capacity and airflow requirements, select the fan, coil and other auxiliaries and integrate these properly to the building control system. This 6-hr Quick Book outlines the key design considerations for sizing, selecting and estimating the capacity and airflow rate of air handling systems. At the conclusion of this quick book, the reader will be able to answer: What is function of Air handling unit and what factors affect its sizing? How are air-conditioning processes depicted on the psychrometric chart? What is difference between room sensible and grand sensible heat factor? How is airflow rate and the cooling coil load determined? What are the five basic AHU arrangements? What are the different types and applications of the fans used in air handling applications? What are the different types of cooling and heating coils? What are the different types and applications of the filters used in air handling applications? What are the different types of humidifiers and dehumidifiers? What are the different types of control valves and their application? How are the air handling unit controlled and the sequence of operation for critical facility? What are the energy conservation features in designing air handling systems?"