A computer-based, one-dimensional model to simulate transient heat and moisture transfer through building assemblies, developed by the Fraunhofer Institute in Holtzkirchen, Germany. WUFI can be used to predict condensation, moisture accumulation and mold growth potential in building assemblies. WUFI is an acronym for the German phrase Wärme Und Feuchte Instationär (translation: Transient Heat and Moisture).