This book presents an analytical tool for the assessment of Indoor Air Quality within the building environment.Application of the HAM(Heat,Air and Moisture)tranfer model and the CFD(Computational Fluid Dynamics)model in a combinational mode is highlighted. It provides also an overview on the resolution of interfacial moisture desorption and absorption problems within the building enclosure in general and in tropical climates in particular. It offers an intergrated design and analysis approach towards the resolution of real world hygrothermal problems in buildings.This is an invaluable text for students of Architecture and Building Engineering in the Universities and Polytechnics as well as for Professional Engineers and Architects engaged in the solution of hygrothermal related problems towards the assurance of acceptable conditions for an optimum Indoor Air Quality. In conclusion, the book is design to serve as a doorway to higher levels of studies in Environmental physics/Building Climatology.