Efficiency of solar energy use for residential heating and cooling

The possibility of using solar energy collected on flat plate collectors situated on roofs for residential space heating/cooling and domestic water heating is considered. The study is carried out on a typical house situated in various locations in Libya. Two types of constructions involving heavy and light insulation, three roof tilts, and three values of system efficiency are considered. The study shows that the demand in a great part of the country can be provided from solar energy by a medium efficiency system, even with light insulation and a horizontal roof. Only in a few locations should the roof be tilted at an angle of 10 °. For a low-efficiency system, insulation is necessary; for a high-efficiency-system, it was found that there is no need for either heavy insulation or tilting of the roof.