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Solar energy can be used directly and indirectly in supplying electricity, heating and cooling of buildings. So, by removing the compressor, a solar collector is used to supply the heating load in a refrigeration cycles. Therefore, in the present article, the energy balance of a solar system is investigated to provide the heating and cooling load required in the air conditioning of a residential building and an office unit. For this purpose, heating and cooling load required for buildings is calculated using carrier HAP software. Then, a double effect solar absorption system is designed analytically using MATLAB and EES environments. Finally, economic analysis of this system is discussed. According to the obtained results, using of the designed double effect absorption system can not only provide the required heating and cooling load of the building, but also efficiency of this system is 25% higher than a single effect system. Also, this system will also be more cost-effective than a split air conditioner in the long run (About 10 years).