Analysis of the Presence of Light in Rasteh and Charsooq of the Grand (Qeysarriyeh) Bazaar of Isfahan

Light, as the most pervasive natural element, plays an important role in an individual’s experience of space. The important place of this phenomenon in various sciences, religions, philosophies, and, above all, its role in perceiving the visual, and environmental effects of architectural spaces is significant. The presence of light and aesthetic perception of space in magnificent Iranian architectural spaces reflect the knowledge and skills of their architects in the use of light. In fact, the wise use of light is one of the significant characteristics of Iranian historical architectural spaces. In addition to providing lighting, in traditional Persian architecture, the use of daylight has met the climatic, physical, psychological, and aesthetic needs. In this regard, Iranian architects have been successful in creative use of light in interior spaces. Various combinations of light entrances confirm this claim. The present study attempts to examine the qualitative and quantitative role of light in a certain type of Safavid architecture, i.e.  Rasteh and Charsooq of the Grand (Qeysarriyeh) Bazaar of Isfahan by scrutinizing the relationship of light and its origins with its functional purposes. The Grand Bazaar is an example of a certain type of architecture that stimulates human senses through its spatial arrangement and architectural components. It is comprised of massive arches that provoke the imagination by a sequence of lights and shadows in curved hallways, and create a kind of expectation in people dragging them to the bazaar intersection rich in light entered from the dome aperture. The present study aims at investigating the quantity and quality of daylight, and different functions of light in apertures according to the behavior and use of daylight in a public-commercial space where using different types of apertures is limited due to the specific functions. Part of this study is performed using a descriptive-analytical method and another part is conducted through software analysis in which natural light is simulated in specific dates and at given times throughout a year. Therefore, the quantitative indicators of daylight are assessed using Honeybee and Ladybug plugins, and Radiance engine. Proper lighting quality means a state in which efficiency, legibility, and optimal energy consumption are enhanced and the space attractiveness and youthfulness, as well as residents’ wellbeing is improved. First, to achieve a constant pattern to simulate the changes of daylight in a building, the software was programmed for two specific days of the year when the sun is at its highest and lowest altitudes; i.e. June 21 and December 21. To analyze the pattern of changes in daylight, simulations are performed at three times of the day, including 9 a.m., 12 p.m., and 3 p.m. Evaluation of daylight can be studied in two types of static and dynamic characteristics. Since the quantity and quality of daylight vary at each moment, there are limitations for static evaluations, and today, the dynamic simulation is more widely used by users. Therefore, the Useful Daylight Illuminance (UDI100-2000)unit, which is one of the dynamic indicators, was considered a good option. This indicator shows how long the natural light in the building is useful during occupancy hours (between 100 and 2000 lux). Results show that there is a specific pattern for using and keeping the daylight in space. The combination of walls and ceiling apertures helps to provide suitable lighting during the working hours in Rasteh of the Grand (Qeysarriyeh) Bazaar in Isfahan throughout the year and during all seasons. As a result, the share of daylight intervals throughout the year are almost constant, and no significant difference is observed in the share of daylight received with the change in season. Also, the amount of daylight received in more than 70% of Rasteh area during 50% of the working hours is between 100 and 2000 lux, indicating a good level of natural lighting in space. The Grand Bazaar is one of the places where the concept of time is perceived. Lighting analyses show that the rhythm and the angle of sunrays along the paths is the most important factor for guiding people who are not visually connected to the outside to understand the time and space direction. Despite the limitations that the Grand Bazaar and its specific functions face in applying various types of light apertures, the results of this study show that the designers have considered the light quantity and quality of bazaar since the early stages of design and they have purposefully and practically designed and programmed the use of natural light in the Grand (Qeysarriyeh) Bazaar. The ideas used in this building can be modernized and architects can use them in designing public spaces.