Journal of Researches in Islamic Architecture

Since the energy consumption has become one of the crisis of modern buildings, modeling the Iranian past architecture patterns could be helpful. The shopping streets as one of the main sectors consuming energy locate near the open spaces it seems, therefore, they need more thermal comfort. However, using passive techniques, the Iranian traditional bazaars architecture solved the problems regarding thermal comfort. The present inquiry aimed at investigating thermal comfort of traditional and modern commercial buildings from the perspective of solar radiation to compare traditional structures (with traditional design and materials) with modern ones (with modern design and materials). Therefore, Vakil (traditional) and Mollasadra (modern) Bazaars (with the same orientation), located in Shiraz with a semi-arid climate,  have been chosen. Vakil bazaar situated in historical context of city and Mollasadra situated in the first modern part built in 1980. A naturalistic approach was applied to investigate the relation between shadow on surfaces, shopping load and cooling needed in summer and the relation between the solar radiation on surfaces, shopping load and heating load in winter first, a number of questionnaires were used to survey 120 samples including both customers and shopkeepers to show the relation between shopping load and cooling or heating need second, Ecotect Analysis 2011 was employed to simulate surfaces with shadow and solar direct radiation in winter and summer to evaluate the relation between the surfaces received shadow and heating or cooling need. The results showed that along with a full shade in summer, the customers of Vakil Bazaar are interested to do shopping almost in all hours since there is no obtrusive solar radiation in contrast, customers of Mollasadra Street experienced a shadow from sunrise to 11:00 in summer morning thus 73.3% of customers in Mollasadra made complaints about the existing shadow since there is no shade in crowded shopping hours and points especially in summer afternoon furthermore, 93.3% of shopkeepers in Mollasadra used cooling and heating equipment which demonstrate congruently of orientation and quality in sunshades with climate. At the end, some suggestions regarding the mentioned problem in Mollasadra have been proposed.

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.

One of the valuable arts in the Iranian Islamic architecture was Girih which has showcased the beauty of the Iranian art by relying on a unique and unprecedented geometry. The generative nature of such an art coupled with granting style to the woodworks through taking advantage of elegant colorful glass and the use of geometrical carvings has been perfected during the course of history.

Girih are lines (strap work) which decorate the tiles. The tiles are used to form Girih patterns, from the Persian word, meaning "knot". In most cases, only the Girih (and other minor decorations like flowers) are visible rather than the boundaries of the tiles themselves. Girih are elaborate interlacing patterns formed of five standardized shapes. The style is used in Persian Islamic architecture and also in decorative woodwork, it could be applied either as lattice frames, left plain or inset with panels such as of colored glass; or as mosaic panels used to decorate walls and ceilings, whether sacred or secular. In architecture, Girih forms decorative interlaced strap work surfaces from the 15th century to the 20th century. Most designs are based on a partially hidden geometric grid which provides a regular array of points While there are various materials regarding the aesthetic aspects and the incorporeal and theosophical origin of such art as Girih but it seems that the climatic dimensions has been less dealt with. In the present study, there is proposed this presumption that the Girih is not merely an ornamental furnishing art and that it is in a functional interaction with day lighting meanwhile avoiding vanity and uselessness in its architecture and also that it takes advantage of masonry proportionate to the regional climate through its adoption of a vernacular approach. Thus, it looks necessary to find an answer to the question that “whether the Girih used in the buildings constructed based on the Islamic architecture designs can be defined in fields with climatic functions?”

Another question which can be set forth here is that “whether the Iranian architect has been successful in taking advantage of Girih works in realizing and deploying masonries, and making use of the daylight and natural ventilation?” To answer the mentioned questions, there is made use of the qualitative research strategies and the subjective information and data have been categorized in terms of the content they bear through exploiting rational reasoning via performing library studies in order to be able to extract the effective functional factors related to the Girih work from the background literature and then, in the next step, select the main target samples encompassing the residential homes from Qajar era (1-Forugh-Al molk, 2-Asadollah Shojaat Asad, 3-Akbar Javanmardi, 4-Parviz Amooee, 5-Jalal Sahebolamr, 6-Habibi Pishehvari, 7-Hossein Ali Tasmim Haghighi, 8-Dabagh Manesh, 9-Seyyed Mahmood Fateminejad, 10-Aliakbar Asgharzadeh).

In order to be able to evaluate and assess the case samples and finally the Girih application frequency in the case samples and the type of their application can be obtained through making use of various sampling methods.

Related to case studies and comparing them to documents wood and glass is the most useful materials in Girih structure.

After finding documents about quantity of Girih in each case study authors started to explore the Girih area into façade area which showcased by “f”. As authors mentioned “f” is made by dividing Girih area (Ag) multiplied by Girih numbers (Ng) in each façade side into window area (Aw) multiplied numbers of each window (Nw).

The study findings indicated that there exists a significant difference between the Girih frequency distribution rates along the western side in respect to the other fronts which concomitantly accompanied by the use of a pier’s vertical parasol the same as a similar configuration in the modern climatic radiation protection system provide for the unfavorable western side light effective control.

The absence of the Girih along the southern side is due to the need for making complete use of the sun light and radiation in this front because the interior spaces situated along this side of the house were used during the winters. The use of the vernacular or the regional climate-compliant masonries in Girih provides for the walls’ thermal control and the non-accumulation of the thermal and heat load along the western side.