The revised version of DIN 4108-2:2013-02 establishes minimum requirements for thermal protection in buildings. It aims, among other things, to ensure a reasonable indoor temperature during the summer and to prevent mold on the interior surfaces of building components. This Beuth commentary familiarizes the user with the changes and new contents of the standard. The first part comments on the original text of the standard paragraph by paragraph, explaining the background of each passage and supplementing it with additional information. Since the standard is used not only for the planning of new buildings but also for assessing the thermal protection of existing structures, the second part of the commentary discusses the historical development of the normative requirements, taking into account the relevant calculation algorithms.