I'm interested to do my m.s. thesis about solar air conditioning. As the high cost, is the main barrier of using solar systems in my country, I'm going to consider economical aspect of the system and try to design a cost-effective (or at least more economically interesting) system. already there are many buildings using natural gas for air canditioning in Iran ,producing so much air pollution specially in Tehran (capital of Iran) so I'm going to propose a solar thermal system to be integrated to existing systems and reduce their energy consumption and emissions effectively.so far, I found combisystems which is used to retrofit existing buildings in some studies. "Techno-economic environmental study of solar combisystems retrofit in Iranian house stock" is the subject which I have considered but there are many similar papers, so I should bring more innovation into this subject. I need your comments to improve this subject Also if you have a better idea, I will be really glad to know Thank you