This study evaluates the energy savings potential of indirect evaporative cooling (IEC) as fresh air pre-cooling in hot climatic conditions in Saudi Arabia. For this purpose, a commercial IEC unit was pilot-tested in a building located in Ras Tanura refinery. The IEC unit effectiveness and water consumption were monitored and verified against published performance data. Energy saving calculation method for hybrid IEC/DX-based AC system was performed and a generalized energy saving chart was generated for various simulated climatic conditions using Ras Tanura building example. Depending on the climatic conditions observed, results show that fresh air pre-cooling using IEC has an energy savings range from 10% to 70% when compared to using DX-based AC system alone. Results are consistent with literature information and should be of a great value to enable HVAC designers evaluate quickly the energy savings potential when applying IEC as fresh air pre-cooling.