An earth-to-air heat exchanger (EAHE) is a shallow geothermal energy utilization technology, which can significantly reduce the building energy consumption. This study aims to investigate the effects of an EAHE on the indoor thermal environment in hot-summer and cold-winter regions. A full-scale experiment was conducted for a continuous 24 h period using two identical buildings (with and without an EAHE) exposed to the same outdoor conditions on typical summer and winter days. Experimental results show that the EAHE provides an average outdoor air temperature reduction of 9.12 degrees C under cooling conditions and increase of 5.53 degrees C under heating conditions. Moreover, the average outdoor air relative humidity increases by 46.89% and decreases by 27.41% in the cooling and heating conditions, respectively; the corresponding average EAHE coefficients of performance (COP) are 7.03 and 4.26, respectively. Compared to that of the building without EAHE, the average indoor air temperature of the building with EAHE decreases by 5.9 degrees C in summer and increases by 4.29 degrees C in winter, and the average walls' internal surface temperature decreases by approximately 6 degrees C and increases by approximately 5.8 degrees C. Moreover, the EAHE system reduces the average building cooling and heating loads by 55.4 and 40.43 W/m(2), respectively. (c) 2020 Elsevier Ltd. All rights reserved.