The paper presents the energetic performances of a window in diverse constructive realization solutions and the thermal protection of its frame. The study made has at its basis the numeric analysis of the temperature field upon the effect made by the joining of the thermal insulation from the walls on the embrasures of the window hole. The heat transfer through the window- wall- insulation ensemble was determined with the help of the "WINDOW- WALL" calculus program derived from the calculus program CIMPSPAT, made by the authors in the variant 2008 (first variant in 1980) written in the programming language Delphi under Windows environment. The analysis of the interior microclimate conditions existing in the dwelling houses from our country, leads to the necessity of a better knowing of the heat transfer phenomena closer to the real phenomenon that takes place in the case of the windows placed in different situations of exploitation. The practical finding of different behavior of windows, the condense phenomenon met on the interior surface of the window framework and the contour in which the window is placed, calls for the necessity of the calculus presented in the paper.