Windows are an essential part of almost every civil building. The existing approach for designing windows is based on ensuring minimum requirements to provide natural lighting functions, thermal protection, etc. This approach does not take into account the interrelationship of certain technical characteristics of windows (for example, heat and lighting characteristics). This leads to the appearance of typical problems at the stage of operating the building (insufficient day light, poor ventilation, etc.). In this work, an analysis of functional and technical requirements of windows of civil buildings was conducted. The review of modern researches of optimal window designs and interrelation of certain technical characteristics of window between themselves was conducted. On the basis of this analysis, the concept of a new complex window design method was proposed. This method is based on the fact that windows are both bearing and enclosing elements of the building. The use of this method will create the standard design solutions of windows for civil buildings of different functional purposes and different climatic areas of construction.