The established textbook and reference work in building physics has been updated and moderately expanded for its 9th edition. In addition to considering the current normative situation, the transition to the Building Energy Act (GEG 2020) is particularly noteworthy. This textbook on building physics thus presents a concentrated overview of the current state of technology in this field. To continue meeting the standards of an academic title, the discussions on various topics have been aligned with the curricula in the field of building physics and, where deemed beneficial, have been deepened and supplemented. Alongside the scientific fundamentals and interconnections, the content includes the essential building physics-related standards and regulations in a compressed form, with a focus on practical application.