Abstarct: Two of the main problems in the world are the reduction of fossil fuels and environmental pollution, due to the use of HVAC system in residential buildings. Therefore, by increasing the efficiency of these systems and using less polluting fuels, the risks can be reduced. Also, considering that the efficiency of each HVAC system is directly related to the climate, in which it is used, Therefore, in the present study, the desirabile of the use of a gas engine heat pump (GEHP) system in different climates of Iran has been examined, by using two economic and technical aspects; and the performance of each of the systems has been presented. Therefore, for the purpose of this study, five cities have been selected as the sample, by using the temperature data, the climate and characteristics of each city, including weather conditions, have been identified in two critical seasons of summer and winter. Then a five- floors building in each of the sample cities is modeled in the Carrier software. With this software, the heating and cooling loads of each building have been calculated, and due to these loads, the dimensions of the cooling and heating systems have been determined. Then, to determine the appropriate systems in each climate, from economic and technical aspects, study was performed. In economic terms, systems are analysed by taking into account parameters such as initial investment, interest rates, and standard economic parameters such as Net Present Value (NPV). In technical terms, systems are measured by two aspects: feasibility of use (the ability of the system to provide the minimum thermal comfort conditions according to the bioclimatic diagram) and also providing welfare conditions (taking into account factors such as pollution, uniformity of the internal conditions, safety and etc.). In the technical aspect, the comparison scale was qualitative; therefore, in order to counting the desirability of each system, two methods of discrete coefficients and fuzzy logic have been used. The results of the research show that the sample buildings in Hamedan and Bandar Abbashave the most need for degree-day and load, respectively, heating and cooling, which is fully compatible with the type of climate determinated for them. Also, by analyzing the results of cooling and heating loads for each floor in all cities, the highest and lowest cooling and heating loads, respectively, were related to the fifth and second floor and also the first and middle floor; Therefore, energy consumption and the cost of it, in the first and second floor were the lowest and the highest cost of energy was related to the fifth floor. Also, the results of economic analysis in all cities showen that, the GEHP system is the most desirable system for providing cooling and heating, and split (in Babolsar) and chiller+heater absorption (in other cities) have had the highest cost for twenty years in net persent value analysing. In terms of the feasibility of use, the cooler+package and chiller+heater absorption have not been able to provide comfort conditions in wet or very humid areas. Considering the welfare analysis, in both methods GEHP is the most desirable, and in discrete coefficients and fuzzy logic method, respectively, cooler+package and chiller+heater absorption is the last one. Therefore, with the integration of two economic and technical aspects, in all cities, GEHP has the best performance and highest desirablity and is at the top of the table. The split is placed in the second position, the chiller+heater absorption and the cooler+package are ineffective in the wet or very hot climate and in the dry climate they have relatively low performance and are placed in the last position.