Dwellings in a Mediterranean climate, such as that of Chile's Central Valley, must provide hygro-thermal comfort both during the cold winters, and the hot days and cool summer nights. Straw, once a material common in Chile's indigenous and vernacular architecture, could meet these demands when coupled with sufficient thermal mass in the form of earth renders and floor finishes. This article presents measurements of dry bulb temperatures and relative humidity, both in physical test chambers and Chilean straw bale homes. The results of these measurements confirm that straw bale construction could provide hygro-thermal comfort with heating demands 28% less than those of constructions that meet the Chilean thermal building regulations. Straw bale, therefore, could provide a viable solution for comfortable, energy efficient, rural dwellings in Chile's Central Valley. Whilst over 40 private straw bale projects have been completed in Chile to date, restrictions applying to projects receiving government subsidies prevent this technology being available to those who need it most.