Today’s trend of increasing window areas especially in public and office buildings results in the problem of excess heat collection inside (greenhouse effect), which leads to higher energy consumption in air conditioning and thus for higher costs. All attempts so far to address this problem have been connected with shrinking of window areas or have involved some other reasons to reduce the overall illumination through the windows, for example via dark tint of the glass. Thus, these solutions always reduce also the natural illumination and lightning, which is most of the time a highly desired property, and the main reason for the increased window area. The most modern state-of-theart techniques involve wavelength selective transparency, which has been used to somewhat prevent the long wavelengths, i.e. the heat radiation (IR part), to penetrate the window. However, even this helps for the excess heating, all this radiation will be reflected back to outdoor and its energy lost. At the same time, as the preventing of the global warming yields pressure to reduce the total energy consumption it also demands to invest more and to increase the efficiency of renewable energy sources. From these the most obvious and widely utilized is the solar energy, whose global energy market has been vastly increasing during recent years. Most of the sun’s radiation energy is located exactly on the IR part of the spectrum. To answer both of the above demands, i.e., to reduce the energy consumption of the buildings via reduced air condition needed, and at the same time to increase the amount of solar energy collected, the project proposes a novel principle of separating the heat (IR part) from the visible light and use it for energy generation, without scarifying parts of the window areas or otherwise reduce the visible illumination