Environmental consciousness leads the construction industry to greater concerns about local adaptation, less waste of resources and energy efficiency In Brazil, earth construction is a feasible approach to house building in many locations and can play a useful part in resolving the housing problems faced by that country, being already a popular approach to providing affordable housing for low income groups within the population, particularly in the Northeast Region of the country, although usually not built correctly. Although used since the colonial period, from 1500, knowledge around earth systems is not formally embedded within the Brazilian building standards and this is unhelpful in terms of promoting quality of performance of buildings thus constructed. For example, appropriate use of high thermal mass in conjunction with natural ventilation, which is frequently used in Brazil due to energy costs, can significantly influence the thermal comfort within residences, but appropriate guidance is lacking. This research considers the combined effects of earth construction and natural ventilation upon thermal comfort within social housing in Northeast Brazil. The main thesis hypothesis is that the use of thermal mass provided by earth construction combined with natural ventilation results in acceptable levels of thermal performance with respect to thermal comfort in both hot and humid and hot and dry climates. The aim is to evaluate the thermal performance of high thermal mass dwellings using adobe system combined with natural ventilation in the bioclimatic zones of BrazilÃÂ¢ÃÂÃÂs Northeast Region. The method explores thermal performance simulation using Design Builder, a graphical interface for Energy Plus program. The assessment uses parametric analysis and the adaptive thermal comfort index from de Dear and Brager (1998). The results suggest that earth construction provides a high number of comfort hours in all bioclimatic zones in Northeast Brazil and ventilation use enhances the comfort sensation.