The study presents the results of typological analysis and simulation modeling analysis of traditional courtyard residential houses in the cold semi-arid climate of Iran. The purpose of the research has been to analyze and evaluate traditional passive environmental strategies and their elements to provide implications for the design of sustainable residential buildings in contemporary time. Five existing traditional courtyard houses in the city of Tabriz, Iran, are used as case-studies to analyze the typology and the solar zoning conditions and to develop simulation models. The Ecotect simulation program is used to calculate the solar gains of the buildings and to analyze the effectiveness of the natural passive systems along with native design strategies in terms of potential solar gains of main and secondary living spaces. However, in the vernacular, not only the awareness of the climatic and topological considerations is important, but also the values, rituals, and beliefs that shape the design of the dwellings need to be considered. The research is based on the hypothesis that vernacular buildings (courtyard houses) of Iran have been environmentally sustainable structures. However, an important challenge of the study has been to avoid the technological bias and to consider the cultural and social aspects and embodiment of the studied houses, as well. The study also addresses the potential short comings that limit the reliability of Iranian vernacular architecture at present in order to arrive at a more holistic understanding of the sustainability of the vernacular architecture in the country.