Indoor molds should be considered a widespread and profound societal problem.The fact that more than 14 million households in the 27 member states of the European Union are suffering from dampness and molds and that approximately 4.6 million of current US asthma cases are estimated to be attributable to dampness and molds exposure underline this point.For many years molds and their implications on human health have been prominently on the human health agenda especially since improved thermal insulation and increased air tightness of the building envelope has led to problems of dampness. Despite the lack of consistent scientific evidence the fear of mold problems may have a restraining influence on the future upgrading of building energy performance.This book aims to describe the fundamentals of indoor mold growth as a prerequisite to tackle mold growth in present building as well as in future energy efficient building. Like all living processes, mold growth requires the availability of water. Therefore, the interaction of molds and water form a pivotal focal point in this book. A sound understanding of this relationship lays the foundation for control strategies in any building, present and future.The book focuses on mold problems originating from airborne moisture in particular as being more complex than commonly assumed. Chapters on allergy, toxins and adverse health effects are included.