Using photovoltaic technology in buildings can mainly be categorized into two main types: Building integrated photovoltaic (BIPV) and building attached photovoltaic (BAPV). During the last 20 years, a continuous effort has been put into developing the exploitation of the transparent surfaces in the building to generate electricity. many aspects shall be considered when analyzing the performance and feasibility of BIPV. Because the window is a multifunction part of the building, allowing the light indoors and generating electricity. That will affect the indoor daylighting, artificial lighting, cooling, and heating loads [3]. Apart from module efficiency, several other aspects should be considered: local climate conditions, presence of shadings (trees or overlooking buildings), façade orientation, and solar path. Geographical conditions may affect the PV temperature coefficient and the actual intensity of irradiance (diffuse or direct). The ability to generate electricity affects the transparency of the window, which also has a remarkable effect on the visual parameters inside the room. In this research the current energetic performance of the reference building, and the potential of using semi-transparent windows as an energetic, and architectural solution for office buildings in Hungary and Syria has been analyzed. After the semi-transparent windows performance assessment an index has been validated that we can use to evaluate semi-transparent windows performance integrated into existing buildings. The research resulted in a comparison of the performance of several types of commercial semi-transparent windows to gain the highest efficiency.