This study deals with exergetic assessment of an educational building heated by a conventional boiler in a heating center. The heating system is examined from the generation stage to the envelope of the building. In general the heat loss calculations are made using both energy and exergy analysis methods. The energy and exergy flows between the stages are obtained using a pre-design tool for an optimized building design. Energy and exergy losses are obtained to evaluate the performance of the system. A conventional boiler in the heating center and a fan coil unit in a room are considered in the analysis. Total exergy input rate is calculated to be 694.5 kW, while the largest exergy loss rate is obtained to be 333 kW. Exergetic efficiencies of the conventional boiler and the fan coil unit are also found to be 13.4% and 37.6%, respectively. (C) 2010 Elsevier B.V. All rights reserved.