This aim of this study was to compare the thermal performance of three buildings which are located at the Kerkenes Eco-center in Yozgat, Turkey. The first of these was constructed with strawbales rendered with mud plaster; the second with aerated autoclaved concrete (AAC) blocks and cement plaster; and the third with strawbales rendered with mud plaster inside and a layer of thin AAC blocks on the outside. The last type of hybrid wall construction has been tried for the first time, in order to take advantage of the thermal-insulation property of straw, combined with the humidity-regulating property of mud plaster inside and weather-resistance property of AAC outside. Temperature and humidity data were collected in these three buildings for certain time periods, concurrently. These data have been compared to elicit the degree of variance in the performance of the three types of constructions. Additionally, computer models of these buildings have also been simulated with Ecotect v5.5 for a comparison of their total energy loads.