Thermal analysis of a novel integrated system of ground heat exchanger and indirect evaporative cooler is performed in the summer conditions of Tehran, the capital city of Iran. A ground-coupled circuit pre-cools the entering air of an indirect evaporative cooler. This circuit includes four vertical ground heat exchangers which are arrayed in a series configuration. In order to have an accurate prediction of the optimum performance of the ground-coupled circuit, a three-dimensional computational fluid dynamics simulation is run. The simulation results reveal that the combination of the ground-coupled circuit and the indirect evaporative cooler can easily provide comfort conditions. Based on the results, the cooling effectiveness of this hybrid system is more than unity and this novel hybrid system significantly decreases the air temperature below the ambient wet-bulb temperature. As a result, the proposed system can be used as a clean and efficient air conditioner. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.