**11. Summary of the chapter**

The inadequacy and inability and the inherent danger in the use of fossil fuels energy and other conventional sources of energy to meet the worlds demands for energy both now and in the nearest future is highlighted and emphasized. The world eventually turning to the renewable energy sources, solar energy in particular, is inevitable, expected and wise. The inevitable impediment such as the earth's atmosphere and its effect on the passage of solar radiation, to the realization of full utilization of solar energy are identified.

The major possible uses that solar energy are put to are mentioned. A specialized and new area of utilizing solar energy, the area of spectral selectivity property of thin films of materials, are highlighted and discussed. Devices such as heat mirror "cold mirror" solar control windows, in buildings, which basic principle is spectral selectivity, to mention a few, are discussed.
