The present study undertakes an exergy analysis of earth to air heat exchanger (EAHE) and applies to a local one in Turkey. Namely, the exergy performance of an EAHE has been evaluated in a demonstration in Solar Energy Institute of Ege University, Izmir, Turkey. Exergetic efficiencies of the system components are determined as an attempt to assess their individual performances. The daily maximum heating coefficient of performance (COP) value for the system is obtained to be 6.18. The total average COP in the experimental period is found to be 4.74. (C) 2010 Elsevier Ltd. All rights reserved.