The effect of courtyards as microclimate modifiers on the sustainability of traditional houses in a region with BWks mesoclimate in Iran was explored. The principle behind traditional Iranian courtyards was investigated to identify the most influential physical–environmental characteristics that can effectively improve energy efficiency in contemporary residential buildings. A field study was performed to analyze various physical elements of six valuable traditional courtyard houses located in a region with BWks mesoclimate in Iran. These elements included the orientation, extension, rotation angle, dimensions, and proportions of enclosed and open spaces, as well as physical bodies (opaque walls), transparent surfaces (openings), and natural elements (water and soil). Results showed that most of the studied Iranian courtyards were particularly designed to enable orientation, dimension, and proportion to act as microclimate modifiers. All survey-based data were summarized and integrated to propose a physical–environmental design model for courtyards as a useful energy-efficient strategy for contemporary sustainable housing in a region with BWks mesoclimate. The proposed model can be generalized to all design cases located in areas with similar climatic conditions

The use of passive systems for climate control in providing indoor thermal comfort minimizes global trends in increasing the energy demand for active systems of climate control which has unacceptable negative impacts on the natural environment. This concept is ignored for designing of contemporary buildings which care less about the environmental impacts. The main objective of this study is to investigate the concept of the traditional central courtyard as a passive cooling strategy for improving indoor thermal comfort in the BS climate of Iran. An empirical field study was conducted to analyze three important courtyard design variants including orientation, dimensions and proportions, as well as opaque (walls) and transparent surfaces (windows), in fourteen valuable traditional houses in five ancient cities located in the BS climate of Iran. Results of this quantitative study, show that Iranian traditional central courtyards were designed based on a careful attention to orientation and geometrical properties regarding the physical and natural parameters to act as an effective passive cooling system. In conclusion, all data sets were integrated to propose a physical–environmental design model for central courtyards as a useful passive strategy which can be generalized for the wider use of environmentally sustainable design principles in future practice concerning courtyards for buildings in BS climate