The thermal potential of Earth-Air Heat Exchangers (EAHE) is experimentally investigated for a placement in Viamao, city located in the south of Brazil. Three independent ducts are buried in the soil, ducts A and B are installed at a depth of 1.60 m and 0.60 m apart, while duct C is installed at a depth of 0.50 m. The thermal conditions of one build named Casa Ventura are improved with the EAHE. The temperatures for the soil, external air and in buried ducts in several positions are acquired along one year (2007). The main purpose here is the achievement of the transient behavior of temperature fields for the external air, soil and buried ducts and the best periods of time for employment of device. Results showed that the months of May and February were the best for heating and cooling the air used in Casa Ventura, respectively. Moreover, it was developed a complete database about the transient temperatures of the soil, external air and inside the building. (C) 2013 Elsevier B.V. All rights reserved.