Journal of Researches in Islamic Architecture

---

Since a large part of Iran is located in hot-dry climate, also the maximum amount of radiation absorbed is done from the roof in low-lying buildings among other facades in summer. And also the maximum area of the outer shell of the building is dedicated to the ceiling. Further, the most energy consumption is devoted to the building, and there is high cost of cooling  in the summer in Iran. Hence the implication of the roof’s shape in providing comfort conditions couldn’t br ignored. On the other hand, the vernacular architecture of Iran, like many other ancient civilizations has provided comfort conditions for many years with lower energy consumption. The double-dome roof is one of the indigenous architecture in hot-dry climate of Iran.  Suitable double-dome is considered to provide comfort conditions in public buildings. By this aim, Kashan, a city of seven thousand years old and a vernacular architecture is chosen. The dome of the Chehel Dokhtaran tomb, that followes the general form of Kashan domes and has certain circumstances of this research, was considered the base. Afterwards the following tests were tried respectively and there were some changes on the geometry of the double-dome of the tomb by computer simulations such as Ecotect, Design Builder and Fluent softwares.
A-conduction: the reduction of heat transfer of the roof the better thermal performance on hot and cool days;
Test 1. Single shell dome is considered by removing the inner shell.
Test 2. The distance between two shells was decreased.
Test 3. The distance between two shells was increased.
B-radiation: the more radiation absorbed is reduced, the better thermal performance of the roof on hot days;
Test 4. The outer surface of the dome is deformed into hemisphere shape.
Test 5. Covering the outer shell of the dome by traditional tile.
C-Convection: the warmer air is less dense than the cold air and always move upward, therefore the more remove the hot air accumulated inside the more comfort conditions provide in summer;
Test 6. Creating windowes in outer shell of the dome.
Test 7. Creating wind-catcher on the top of the dome.
The results of conduction, radiation and convection tests were compared with each other:
Considering the dome with two shells regardless shells distance from each other is significantly effective to provide comfort conditions in hot and cold days, due to reducing heat conduction from outside to inside and vice versa.
In the case of double shell dome with thin air layer like 5cm thikness between shells, the air layer acts as thermal insulation and the heat transfers only by conduction in such a way that the convection heat transfer isn’t done. Compared with the main dome, the heat was crossed from the outer shell of the main dome during the day, and is collected at the top of the space between two shells; pass out while the weather temperature decreased at night, in test2 the heat transferred later to the outside. So, indoor air will experience higher temperature. And on winter, the heat will be transferred faster to the outside. So, the inside temperature will be hotter in summer and colder in winter.
In test3 the distance between two shells is increased to 3m and be filled by air. The heat will be collect under the top of the outer shell and will be far from the surface of the inner shell, although the interior vortices are formed completely and faster than the basic form in summer day and night and more time is required to transfer heat from outside to inside and vice versa. But on winter night the heat was gathered under the inner-dome will transfer to the air between tow shells. Compared to the main dome the heat will be transferred faster to the outside because of the stronger vortices. So in the winter inside air will be colder.
Comparision Nari dome form and the hemesphire dome with similar area, Nari dome is more suitable, thanks to the more surface area of it that is placed in shade and less direct and indirect radiation absorbed on hot days.
If the outer surface of the dome covered by bright tiles, reduces the absorption of radiation and the air temperature will be decrease on summer.
Air conditioning between shells caused evacuation of gathered heat and in summer reduces inside air temperature.
Wind-catcher causes negative pressure of the wind power on the outer dome, and make hot air that was gathered under the inner shell pulling out. And through heat exhaust, inside ventilation is formed, which is desirable on summer.
The general result is: The best geometric configuration to cover the roof of the building in desert climate of Kashan and similar climates, is the double-shell dome with outer-shell in the form of Nari-shaped and the inner-shell in the form of sphere sector, which similar to the dome of the Chehel Dokhtaran tomb of Kashan. Therefore with installing windowes on the outer shell and installing wind-catcher on top of the dome to remove the hot air. Also covering the dome by Iranian tiles, reduces the absorption of radiation. So the air temperature inside the building reduces on summer. Also close windowes and wind-catcher would be desirable, on winter.

---

The lack of proper understanding based on the fundamental and original notions of persistent architectural patterns of the house has led to disturbances in the fundamental structures of contemporary home architecture. The design of a home-based on sustained principles and archetypes has had complexities that have been taken into consideration in recent traditional architectural patterns have been one of the most prominent and important ways to meet the needs of their time. Among its achievements are climate and design adaptation, the proper use of natural energy, and the enjoyment of comfortable space for humans. It seems that by examining the nature of the archetypes, their applications in the residential design are represented. In this paper, after reviewing the basic principles of residential patterns in case studies, the design criteria used in them are extracted. The purpose of the research is identifing the old architectural patterns of the Kashan houses and its efficiency in designing modern residential architecture. The research method is based on case studies that analysise the content of the texts to identify the conceptual framework for understanding the design criteria. An overview of the role of patterns can be pointed out in terms of its functionality to meet the needs of its time, such as the central courtyard, the Godal Baghcheh (the construction of the main spaces at the negative level), spatial hierarchy, spatial expansion, etc. They are, for example, placing the outdoor space in the center of the house, orientation based on the use of natural factors such as sun, water and wind, roof tiling, sun light and even engaging such as colored glasses from a set of patterns which has a good response in terms of climate, style, aesthetics, and performance. Using the archetype in today's architecture, architect should pay attention to the reason for the emergence of the old patterns. What was the reason why each pattern was originated and what needs to be answered? Finally, how can they be improved by increasing their qualitative dimension with the continuation of them in the formation the spaces of today's homes? In addressing each of the dimensions we want to identify the criteria we can use to cite impact of each criteria to form a pattern-based space. The research is qualitative and analyzes the content of theoretical texts by the research samples. Finally, an analytical review of approaches and considerations consistent with the content of the concepts of theories is obtained to assess the qualitative criteria achieved. Issues raised through representation are examined. Using this method, the studied houses are considered based on the proposed criteria based on the shape structure. Therefore, in this section, the dimensions of the climate, spatial organization, relationship with the earth, materials, proportions and spatial geometry in the four dimensions will be studied to summarize the desired dimensions. Considering the basis of the research, which is based on qualitative analysis, sampling was selected randomly from houses built in the past and present in both Kashan and Yazd. In this regard, the principles based on architectural design patterns in the past and continuity in today's architecture is extracted. Then, based on the conceptual model presented, the criteria were classified into the components of natural structure, physical-space structure, and visual structure. After assessing the reliability of the components by the experts, the level of impact and more comprehensive principles were identified. Subsequently, the semantic analysis of each that was carried out in the studied samples. The results of the research show that the architectural patterns of the houses studied in natural, physical, spatial and visual structures through 15 concepts of hierarchy, spatial equilibrium, flexibility, introversion, collective activity, sensibility, security, energy efficiency, confidentiality, confinement, vernacular materials, static, natural varieties, natural elements, and architectural negative-level are recognizable. These concepts are introduced in the formulation of the criteria of spaceism, introversion, naturalism, and structuralism. These items are more likely to be found in the homes of Saleh and A house, Yazd. In the later spatial organization, lowering the level of clearance (architectural negative-level), the Govdal Baghcheh means the use of the yard in the center of the house and the use of natural lighting and communication with the open space can be viewed on a wider level. In the dimension of the space hierarchy, space communications are considered in two horizontal and high altitudes, open, semi-open, closed, and spatial space, based on space and movement. In the pattern of introversion, there was no direct visual relationship between the inside and the attention to the design of open spaces that could provide direct visual communication; the confidentiality of limiting the attainment of the mental comfort of residents in the home and the observance of safe privacy; spatial communication to develop the activities of the residents of the house is examined. Finally, by evaluating these criteria, the archetypes that can continue in the architecture of today's homes are presented in the form of an analytical-applied model.

---

---

Statement of Problem: To improve the identity of residential architecture, it is required to enhance the semantic dimensions in the design. To do this, the principles of traditional residential architecture in hot-dry climates, as one of the richest physical-spatial models for Iranian houses, must be applied. On the other hand, one of the best strategies for giving meaning to works is to use signs by examining users' mental image. However, nowadays, semantic concepts such as users' perception or mental image are less considered or ignored in the residential architecture due to factors such as economy or superficiality in design. This is due to the ignorance of the user-environment relationship at the educational and executive levels of design. Therefore, there is a need for finding a practical approach to semantics by extracting the signs existing in traditional houses. To meet this need, the present study seeks to answer the question "What is the role of signs in the semantic aspects of traditional Persian houses in hot-dry climate?" Since the use of successful traditional architectural models is another way for enhancing the identity of residential architecture, it seems necessary to find and use them in contemporary housing in accordance with the current situation. The research background mainly focuses on finding physical patterns or semantic principles in Iranian houses from non-semiotic perspectives, so obviously, there is a need for research on the extraction of patterns using semiotics to match the design with the users' reading.
Research aim: The design performed "only to satisfy the building function", cannot meet such affairs as identity. So, it must meet the perceptual needs to manifest identity in architecture, and this will be possibly achieved if the design is performed through a semantic process. To this end, the present research seeks to find out how the categories of signs match with the components affecting mental image in traditional houses in the hot-dry climate. Since the present study looks for the effect of signs on meaning in traditional housing design, "sign" is an independent variable, and "meaning in housing design" is a dependent variable. Accordingly, the research hypothesis is as follows: "Using the categories of signs has played a role in the meaning of traditional residential architecture in the hot-dry climate". The present study aims to extract the principles of semantics from the semiotic perspective to use in contemporary residential architecture to pay more attention to the identity and semantic dimensions of today's living environments.
Research Method: the present research is a qualitative study in which applied examples of traditional residential architecture in the hot-dry climate are studied using "document mining" and "qualitative content analysis". In the "data analysis" section, the matching of the components affecting the mental image with the categories of signs is evaluated by examining the examples of traditional Persian houses in the hot-dry climate. Accordingly, the relationships between the categories of signs, including "index", "symbol", and "icon", and the "spatial", "human" and "temporal" components affecting mental image are analyzed. It should be noted that the case studies are selected based on two criteria: 1. having spatial and physical richness, and 2. having a design in which one can observe the matching of the categories of signs with the components affecting perception. The authors attempt to select those cases having the features observed in most of the traditional Persian houses in the hot-arid climate. In the selected samples of traditional Persian houses in the hot-dry climate, any analyzable relationship between the categories of signs and factors affecting mental image is analyzed. It should be noted that it was attempted to select those components common to most traditional houses in the hot-dry climate.
 
Conclusion: The results indicate that in traditional houses in the hot-dry climate, "icon", "index", and "symbol" have been used as a means to express meanings by being matched with human, environmental and temporal components affecting users' mental image in accordance with their cultural context. Moreover, the results show the matching of the environmental components with the categories of "icon", "index" and "symbol". The temporal components affecting the users' reading show their highest degree of matching with the category of "icon". The "icon" and "symbol" categories also have the highest degree of matching with the human components affecting the users' reading. Therefore, one of the effective strategies for providing a semantic-oriented residential design is to use the components of "function", "body", "scale", "historical background", "individual experience", "social event", "physiological and psychological factors", "individual and social behaviors" of users and also attention to "components affecting the sense of belonging to place and community" in the form of different categories of signs in the design. Therefore, using different categories of signs, which match with the factors affecting the users' mental image, considering the temporal, spatial and human context of the design can be a way to consider meaning and identity in today's housing designs.

---