A simple methodology is introduced to obtain an empirical relation between power consumption and indoor-outdoor temperature variations for a small residential building. The effects of house occupants, air/moisture leakage, material deterioration, etc. were not considered in the analysis. The Tuskegee Healthy House was used as a test building for the experiment. Empirical equations for power consumption as a function of temperature area differences were obtained from the measured data of winter 2009 with and without mechanically-induced ventilation fresh air, i.e. using fan "ON" and fan "OFF" condition, respectively. The equations were applied to the measured temperature data of winter 2002 to compare and evaluate the thermal performance of the test house. The equations agree favorably with the winter 2002 data revealing that there is no significant difference in power consumption values of winter 2002 and winter 2009 and, hence, no appreciable change in the thermal performance of the house. The methodology presented in the work can be utilized to compare and evaluate the thermal performance of a given building envelope from season to season and between the same seasons in different years. (C) 2009 Elsevier Ltd. All rights reserved.