A simplified analytical model is developed to study the year round effectiveness of a recirculation type earth air heat exchanger coupled with a greenhouse located in HT Delhi, India. The performance of the system was evaluated in terms of thermal load leveling and coefficient of performance. Calculations were done for typical winter and summer day in year 2002. Temperatures of greenhouse air were found to be on an average 6-7 degreesC more in winter and 3-4 degreesC less in summer than the same greenhouse when operating without earth air heat exchanger. Predicted and measured values of greenhouse air temperatures exhibited fair agreement. (C) 2003 Elsevier B.V. All rights reserved.