"Chahar Soffeh" is often considered as one of the oldest forms in Iranian residential architecture. The cruciform form, besides its climatic and structural characteristics, reflects spiritual meanings and is repeatedly used in different building designs and typologies. In Iranian architecture, this form goes beyond a mere expression in primitive building typologies and works as a hidden schema underneath the spatial organization of building typologies and creates space typologies like ‘Chahar Eyvani’ (four portals), ‘Chahar Bagh’ (four gardens), ‘Chahar Taghi’(four arched), and so on. A morphological examination of ‘Chahar Soffeh’ as a template in various examples of residential plans can provide us with a systematic understanding of the emergence and development of this template in the Iranian architecture history. Examining various plans of residential buildings, this article identifies the benefits that ‘Chahar Soffeh’ offers as a spatial component of residential architecture. Benefits include: Creating a moderate microclimate in the house in the context of dry climate of deserts;  providing a large space despite its small size in the central courtyard; its geometric pattern that is very easy to implement; and finally, offering a space which can accommodate various functions in the central space of the house. Adopting a phenomenological approach in investigating some examples of residential architecture, this research depicts the design process of ‘Chahar Soffeh’, step by step in hypothetical cases. By surveying various patterns of ‘Chahar Soffeh’, the research traces this template not only in ‘Kooshks’ in Iranian Gardens but in ‘Howz-khaneh’, ‘Orosi’ and even in ‘Tehrani rooms’. After investigating various plans of Chahar Soffeh in residential buildings, the article traces the design of Chahar Soffeh to a variety of spaces such as: ‘Howz-Khaneh’ (pool rooms), ‘Orosi-Khaneh‘ (sash house) and even rooms called ‘Shekam Darideh’ and ‘Tehrani’.

In addition to looking at the benefits of ‘Chahar Soffeh’, this article presents the process of the development of this space in different hypothetical residential plans. In this way, this research depicts the design process of ‘Chahar Soffeh’, step by step in hypothetical cases. The findings of this article identifies the main benefits of ‘Chahar Soffeh’ as: Creating a nice balance of sun and shade in an arid climate, providing a wide space in a limited area as well as its geometrical design which facilitates its implementation. ‘Chahar Soffeh’ can be found in cities such as Boshruyeh and Tabas. These cities provide more original cases of a historic house with ‘Chahar Soffeh’, where the residential architecture has an introverted character with a small courtyard at its center and four portals (Ivans) on each side. In Zavvareh, however, houses have a covered central space and are within the process of transformation to larger houses with ‘Howz-Khaneh’ or ‘Kooshks’. Eventually, in courtyard houses of Iran central plateau, ‘Chahar Soffeh’ disappeared from the yard and emerged in spaces like ‘Howz-Khaneh’, ‘Tehrani’ and the like. In any case, ‘Howz-Khaneh’ remains as the main mode of expression of ‘Chahar Soffeh’.