By considering in-between spaces as a principal component of Iranian architecture, the present research attempted to benefit from Exploratory Factor Analysis (EFA) to seek for principles which lead to the creation of this function for spaces such as: vestibule, veranda and yard in Iranian houses. The authenticity indices. The reliability of the questionnaire was calculated through cronbach's as equal to 0.864, which is satisfactory value. Moreover, in order to determine construct validity of the questionnaire, EFA methods were utilized. The results of KMO test produced value of 6730 which shows factors appropriate goodness of fit.
Since privacy and personal zone and territory have always been of great importance in Iranian architecture (Memarian 2006), designing separative and connective spaces such as vestibule, veranda and yard has been highly regarded by Iranian designers over years (Noroozi 2013; Ahmadi 2012).
The present study showed that the role and function of such spaces in Iranian architecture is more solely more than solely separating spaces. In fact, in-between spaces in Iranian architecture created spatial organization hierarchy and continuity (Ahmadi 2012; Aeinifar 2003).
As shown in Table 2, the most crucial role of in-between spaces was specified as spatial organization (24.887). The reason might be hidden in the importance of symmetric axis and spatial order in Iranian house plan (Memarian 2006; Pope 1965). As suggested by the studies in literature review, in-between elements of space in Iranian houses are organized in 6 manners which according to Ching (1979) represent spatial positioning of elements in a certain space or zone.
Culture and importance of private zone have decisive roles in organizing spaces (Ardalan 2001; Memarian 2006). Therefore, as reflected in the applied questionnaires, culture and climate are two substantial factors which a site imposes on the physique, while cultural and climate-oriented factors have led to the formation of introvert houses (Memarian 2006). Such introverted nature in the entrance is provided by vestibule as a filter followed by yard (see Fig. 9). Yard is considered the mediator between semi-private space (vestibule) and private zone of the house which is located in the center (completely private sections belonging to family members) (see Fig. 9). Whereas other spaces have been situated around that via a repeated rhythm. At the next level, these spaces have organized total houses space on specific axes in a relatively symmetric manner, creating an organized whole. Veranda and vestibule are located in the two extremes of the axis while the yard is placed in the center (see fig Fig. 10). positioning of in-between spaces on major axes (Aeinifar 2003) and from of such spaces creates a geometrical organization, which both causes observers attention to be attracted and the rules and regulations considered by the user to be provided, as asserted in Lang (1987). Therefore, it can be inferred that selecting types of components, connections between them and organizing them within the housing domain follows a kind of order and organization fundamentally, such geometrical order is manifested in from of an architectural work, present in its separate parts (Norberg-Shutlz 1980).
Edward T.Hall (1990) has mentioned activities and territory as affecting spatial organization. What T.Hall (1990) introduces as organization model is to use spaces with semi-fixed-features as a method of activity organization technique. These activities are supposed to be adapted to the users' culture. Vestibule, veranda and yard are such spaces (Aeinifar 2003).
Vestibule is both the entrance space and a location for gathering of strangers or gusts before being permitted to enter. It is also a place for dealing with those who do not tend to enter the house, or family private zone (Shah cheraghi 2011). This space is in accordance with Rappaport's (1977) definition of crowded spaces which are in charge of social controlling by giving the choice of selection and the possibility of interaction. Such functions are example of the role of vestibule (Hashti) in Iranian houses.
Yard (Hayat) is a place for living as well as a separative space. During hot spaces. It is appropriate choice for family living especially for houses located in hot arid climate. Veranda (Eyvan) is also a liveable place; a semi-open space connecting interior and exterior. The most appropriate definition for in-between spaces might be found in Humphry Osmond's; words who terms them "sociopetal spaces", as asserted in Hall (1990).
Therefore, according to previous studies, it can be claimed that all these 3 spaces have the potential of providing privacy for users (Ahmadi 2012; Memarian 2006) while privacy is an issue in accordance with existing pattern of activities, culture background, personal expectation and personality options. Thus, and space designed based on such principles, meets the three major needs of safety, identify and motivation (Pastalan 1970; Lang 1987; Altman 1975).
At the next level, the index for the factor of hierarchy was specified. In general, hierarchy encompasses primary and secondary elements (Meiss 1990). The elements creating hierarchy in an organized set are usually dominant ones (Meiss 1990). The difference is evident among forms, scales, spaces and visual systems, while the distinction is well recognized between the manner of using them compared to other parts. Such differences reflect the symbolic role of spaces in organizing the whole body (Ching 1979). As illustrated in Fig. 10, regarding size and form, those spaces differ from private zone situated around the yard in a linear order. Vestibule which usually has an 8-dimensional (Octa-gonal) shape in plans, is smaller than all other intermediate spaces, located to a corridor which facilitates limited visual contact to the yard. Located in the center of this symmetric organization is the yard which has acquired a broad rectangular shape with private zones forming around it. In fact, the connection between closed and open spaces and nature is supplied by the yard which plays the sociopetal role.
The third variable of hierarchy factor concentrates on different values corresponding to various spaces within a house. These values are determined by users' needs and desires as well as designer's choices; they might be based on personal preferences, cultural or team decisions (Ching 1979). In-between spaces have been placed in Iranian house plans both to have a symbolic function and to create aesthetic visual attraction via a hierarchical system among building parts. The most essential value created by these spaces is that of territory and proper definition of privacy. Organization among elements of between-ness in a house is seen through public areas which lead to semi-private spaces under certain hierarchical pattern, finally ending in private spaces of the housing; a taxonomy from public to private. In such house, private space does NOT begin in the entry threshold, rather special vivid rules of hierarchy and territory govern the formation of house structure (see Fig. 10 & Table 3).
At last, continuity was specified as an influential factor on in-between spaces through index Z. Continuity or overlap between spatial elements leads to the reduction of significance by separate parts of the housing (Meiss 1990). According to Alexander (2002), active centers are formed and strengthened through bordering; a property which is well realized in traditional architecture, but missing in modern architecture. Alexander (2002) maintains that continuity in various elements of nature is responsible for the creation of functional characteristic and sustainability, in turn.
The necessity of involving spaces in housing plan without physical border which are characterized by visual and physical continuity, is evident in Iranian houses (Ahmadi 2012). Open/closed and semi-closed spaces are located next to each other connecting public and private zones (Norouzi 2012). Spaces playing the role of articulators attach others as mediators (Bemanian 2015).
Vestibule, veranda and yard have contacts with their previous and following spaces visually and physically, and this connection is continuous (Aeinifar 2003). In other words, the three spatial groups (open, close, semi-closed spaces) are not built in isolation or separately, rather each one is the continuation of another one, making each other meaningful. This continuity in combining spaces creates the feature of "expansion". For example, veranda is the expansion of rooms and rooms are the expansion of veranda. It is worth mentioning that no interruption or stop occurs and spatial dynamicity continues in spite of strict control of territories and values (Haeri 1995), (Balilan 2011). That is why presence in any of these spaces creates vision, view to the adjacent spaces which might need to be restricted to enhance privacy.
Another factor owned by continuous spaces in the feature of connecting interior and exterior (Kim, 2015), which is, in fact, the nature of in-between spaces (Nooraddin 1998, 2002) vestibule is located between the public space of outdoor (i.e, city) and private space of the housing which belongs to the household members (Aeinifar 2003). However, by entering vestibule, are does not enter the family's private zone. Guests or strangers, after which the mediating space of the yard is situated; a semi-private space used as living area in hot, arid regions. Veranda is a semi-open space, connecting open and close spaces and playing the role of a passing area closed spaces are in contact due to the presence of this semi-open space (see Fig. 11) (Haeri, 1995). From spatial point of view, in addition to the features mentioned, veranda creates spatial diversity, variety, cohesion and distinction as well as continuity between indoor and outdoor (Mahmoudi, 2005).
Yet another technique for creating continuity is to change transforming spaces into functional ones. In this case, a single spatial component can have two or more definitions simultaneously. A good example would be the gallery which I turned into a passage in Venturi's works, or Huller's entrance wall which could be a wall with a large opening or only two fiber glass columns (Mertins 2008). Such connections between spaces-even opposing ones-are linked (Ardalan 2001; Martins 2008). These spaces, in fact, encompass a part of the identity of both original spaces which connect them, what is the discussed as "experiencing the continuous phenomena" (Kim 2015). In-between spaces in Iranian houses not only put a distance between building elements or separation causes the manifestation of independent identify by any spatial element, whereas the same indication can create a unified, specific whole having unique, tight knit identity due to the attachment of parts (see Fig. 12) (Ahmadi 2012).
In Iranian traditional houses, along with daily and seasonal changes, different housing sections are adapted to the required functions. The yard adjusts spatial components and various activities, as well as organizing all the needed alterations to manage indoor activities. (Aeinifar 2003).
On the other hand, continuity of elements is made possible through connective constituents to create a single whole. Entrance space and rooms are connected through vestibule and rooms. Connective spaces not only facilitate passing but also they play the role of pause an short stay spaces as well (e.g veranda and yard). (Ahmadi 2012; Aeinifar 2003). As a part of interior, although that, it has no direct overview to the private or even semi-private spaces of the house.