The energetic performance of Balcova geothermal district heating system (BGDHS) and Salihli geothermal district heating system (SGDHS) installed in Turkey is investigated for building applications in this study. The essential components (e.g., pumps, heat exchangers) of these geothermal district heating systems are also included in the modeling. The present model is employed for system analysis and energetic performance evaluation of the geothermal district heating systems. Energy flow diagrams are drawn to exhibit the input and output energies and losses to the surroundings by using the 2003 and 2004 heating season actual data. In addition, energy efficiencies are studied for comparison purposes, and are found to be 39.36% for BGDHS and 59.31% for SGDHS, respectively. (C) 2005 Elsevier B.V. All rights reserved.