This book provides substantial information on thermal insulation. Thermal insulation is fundamentally defined as the technique of reduction of heat transfer between objects which are in thermal contact or in range of radiative influence. This book provides fundamental practical and prospective applications of the concept of saving energy and also offers methods and approaches regarding this subject. It demonstrates several methods related to the concept of thermal insulation, like the processes and endeavors to build an efficient passive building model. This book will be beneficial for readers interested in this field.