After the industrial revolution, men intended-more than ever-to use energy, specifically the fossil fuels. In spite of providing comfort conditions for human life, too much use of these energy resources can cause the pollution and destruction of environment. The result is the threatening of the environment and the continuity of life on the planet Earth. Hence, the environmental concerns in the 1970s caused the emergence of a new concept entitled as sustainability in all sciences and industries. Therefore, construction sectors -as one of the main consumers of energy- are required to follow sustainability principles, as other disciplines do. One of the techniques in planning green architecture to reach the optimal usage of clean energies and, subsequently, to reduce environmental pollution is to have central courtyards around buildings. This research considers the effect of different parts of a courtyard building on the operative temperature and solar gain per square meter in Isfahan. Therefore, three traditional houses have been chosen and simulated in DesignBuilder as case studies.