Lighting Analysis of Single Pendentive Dome Mosque Design in Sarajevo and Istanbul During Summer Solstice

Lighting Analysis of Single Pendentive Dome Mosque Design in Sarajevo and Istanbul during Summer Solstice Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021

Ahmad Sanusi Hassan and Yasser Arab School of Housing, Building and Planning, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia

This study analyzes lighting performance in single-pendentive-domed mosques, a type of architectural design common during the Ottoman era through a discussion ofthe Orhan Gazi Mosque in Istanbul, Turkey, and the Ferhadija Mosque in Sarajevo, Bosnia-Herzegovina. Our lighting assessment was conducted during the summer solstice. This study applies simulation analysis to the selected mosques using Autodesk 3ds Max Design 2012, which creates a lighting simulation showing indoor illuminance levels at hourly intervals. A weather file is added during the simulation process to accurately replicate local weather conditions. Our analysis shows that both mosques have illuminance levels of Scale 3 and 4, brightness levels not demanding high visibility and suitable for reading areas respectively; illumi - nance levels are slightly higher at Ferhadija Mosque than at the Orhan Gazi Mosque. The study concludes that mosques with single-pendentive-domed roofs have interior illuminance levels designed for tasks not demanding high visibility and suitable for reading areas, expressing the lighting quality of sacredness inside the mosque, and that this explains their popularity not just in Istanbul, capital city of the Ottoman Empire but also in Bosnia-Herzegovina.

Keywords: single pendentive dome, Ottoman mosques, illuminance level, Sarajevo, Istanbul

Cette étude analyse l’efficacité de l’éclairement des mosquées à dôme à pendentif simple, un type architectural commun durant la période ottomane, en prenant les cas de la mosquée Orhan Gazi à Istanbul en Turquie, et de la mosquée Ferhadija à Sarajevo, en Bosnie-Herzégovine. Mesurée lors du solstice d’été, notre évaluation de l’éclairement dans ces deux mosquées a été effectuée grâce à Autodesk 3ds Max Design 2012, qui crée des simulations de niveaux lumineux intérieurs pour chaque heure de la journée. Un fichier météorologique a été combiné à ces simulations pour reproduire l’ensemble des conditions météorologiques locales. Notre analyse montre que les deux mosquées atteignent les niveaux 3 et 4 d’éclairement. Ils sont un peu plus élevés dans la mosquée Ferhadija par rapport à celle d’Orhan Gazi. L’étude conclut que les mosquées à dôme avec un pendentif simple ont des niveaux d’éclairement de niveaux 3 et 4 (respectivement des niveaux ne nécessitant pas une visibilité élevée ou des niveaux de visibilité suffisante pour les espaces réservés à la lecture), ce qui explique leur popularité non seulement à Istanbul, la capitale de l’Empire ottoman, mais aussi en Bosnie-Herzégovine.

Mots-clés : dôme à pendentif simple, mosquées ottomanes, niveaux d’éclairement lumineux, Sarajevo, Istanbul

Introduction Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 Our objective in this study is to show that the pendentive dome mosque design provides good indoor lighting, thus explaining why this architec - tural style was popular in the design of mosques in the Ottoman Empire. Pendentive-domed mosques are common in contemporary mosque design in Turkey and the Balkan region. This type of construction was introduced into the Balkan region, especially in Sarajevo, in the 15th century by Ottoman master builders, as an architectural marker of Ottoman heritage. Assessment of illuminance levels in these mosques will reveal the relative illumination inside each mosque. Our computer-simu - lated analysis is limited to the period of the summer solstice, when the sun is travelling along the Tropic of Cancer, to assess peak levels of illumi - nance. The summer solstice was chosen on the grounds that how much outdoor light a building design captures is most important when there is maximum outdoor light to be captured, as well as to considerations of controlling the lighting level to express sacredness in the indoor area of the prayer hall. The assessment measures lighting design, lighting quality, and its effects on people inside the existing mosque area, not the design of the space or artificial interior lighting. The Orhan Gazi Mosque in Istanbul, Turkey, and the Ferhadija Mosque in Sarajevo, Bosnia- Herzegovina, are compared via a lighting simulation run on Autodesk 3ds Max Design 2012. A unique feature of a pendentive dome is that it creates a vast interior space, twice as high as a traditional dome, and allows natural light to penetrate inside the mosque, a crucial factor in providing light for the worshippers who gather there. This type of design also maximizes interior reflected light, and thus the architectural features of the building are high - lighted. The light that filters down from the many small windows tucked beneath the dome structure brings light into the space in a way that seems to intensify the mosque’s sense of sacredness (Hillenbrand 1994). Mosques designed with pendentive domes were the work of Ottoman master builders who reinvented the architectural style of the Hagia Sophia, built by Byzantine master builders, with more efficiently designed wall openings (upper and lower windows) to incorporate natural light into the mosque design (Necipoglu 2005). Pendentive dome design is also common in Byzantine architecture. A pendentive dome is essentially a “dome built above a dome,” with an upper dome that seems to be “hang - ing in the air” (Mango 1976, 107–14). During both the Byzantine and the Ottoman periods, architects were restricted to design schemes that could

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) Lighting Analysis of Single Pendentive Dome Mosque Design 165 be accommodated in a load-bearing structure. Because a pendentive dome has no ribs, columns, or ring beams built on the dome and wall structural system, it must be capable of bearing its own weight by means of four giant arches. The upper dome in a pendentive system is supported by four grand arches that, in turn, create the frame for a lower dome. This Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 type of construction has the added benefit of reducing demand for build - ing materials such as stone, brick, and marble; this minimalist approach later led to the development of the concept of dematerialized construc - tion. There are six types of pendentive domed mosques in Ottoman archi - tecture: the single, earring, multiple, duplication, courtyard, and earring courtyard plans (Hassan and Mazloomi 2010a). This study focuses on the single-pendentive-dome design, the most basic of these plans and the most common type of mosque built in the Balkan region, especially in Bosnia-Herzegovina. The building plan of a single-pendentive-dome mosque (see Figures 2 and 4 below) consists primarily of a square and a dome. The square (or rectangular) form on which the dome rests, often punctuated by door and window openings, marks the confined space of the main prayer hall. This square structure, however, cannot immediately accommodate a circular dome above it; tertiary semi-circular elements, known as squinches, are therefore added to bridge the space between the square below and the dome above. The squinches, nestled against the dome, look like triangle domes. In addition to relieving the weight of the dome above, they allow the architect to include a line of small windows along the base of the larger dome, which allow a great deal of natural light into the interior of the building. The dome is indicated on the plan by a circular dotted line, which represents the interior void of the prayer hall, a space twice as high as its ground-floor width or length, under a pendentive dome as the roof cover. The dotted triangles indicate the squinched arches. In some cases, a dotted semi-circle attached to the circular line represents the attached half-dome or semi-dome roof covers. The number of half-dome roof covers may be more than one, depending on the number of half-domes attached to the primary pendentive dome’s structure. Many mosques have an additional riwaq (entrance corridor) area. In a single-pendentive-domed mosque, the size of the dome deter - mines the size of the overall structure the larger the dome, the larger the of mosque (Hassan and Mazloomi 2010b). The dome’s load is supported by four giant arches, which form the ground dome that, in most cases, is hidden in the thick perimeter wall. The joints between these arches and the dome are typically surmounted by squinches. In some cases, up to four semi-domes radiate out from the large dome, providing additional indoor space.

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Materials and Methods

The indoor lighting performance of the two mosques selected for this study was evaluated using illuminance levels on a measurable scale. Illuminance levels were measured in lux or lumen per metre square Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 (lumen/m 2), essentially the measure of the amount of luminance (lumen) per 1 m × 1 m surface area. Using this measurement, we will determine the indoor lighting performance by comparative analysis (Runsheng, Meir, and Etzion 2009). Building designs that use daylight are considered as having excellent passive design. Daylight, a passive form of lighting, is preferred because it comfortably matches human visual response. The projected “dome above the dome” plan allows for maximum sunlight penetration. The amount of daylight penetration into a building through windows and doors serves dual functions; these openings not only admit natural light into the indoor area but also allow the occupants to have visual contact with the outdoor environment (Chel, Tiwari, and Chandra 2009; Chel, Tiwari, and Singh 2009).

The Case Study

Like mosques in other parts of the Ottoman Empire, the Orhan Gazi and Ferhadija mosques were important symbols of regional architecture, portraying the beliefs, culture, and politics of the local Muslim commu - nities (Saoud 2004). The Orhan Gazi mosque is located in Istanbul, at 41°00’ N, 28°59’ E; the Ferhadija mosque is located in Sarajevo, at 43°51’ N , 18°26’ E. Sarajevo’s latitude is about 2°50’ north of Istanbul’s (see Figure 1). On 21 June 2011 (summer solstice), sunrise in Istanbul was at 5:32 am and sunset at 8:40 pm, for 15 hours 8 minutes of daylight; sunrise in Sarajevo was at 5:04 am and sunset at 8:32 pm, for 15 hours 28 minutes of daylight (i.e., 20 minutes more than in Istanbul; SunriseSunset.com 2012). During the summer solstice, the sun is at its most northerly latitude, circling the Tropic of Cancer at 23°26’ N, slightly south of both Orhan Gazi and Ferhadija mosques. Both mosques are located in regions that were once part of the Ottoman Empire (Pasic 2004). Orhan Gazi mosque (see Figures 2 and 3), also known as Gebze Orhan mosque or Sultan Orhan mosque, is located in Gebze District, Istanbul. It is named for the Ottoman Sultan Orhan Gazi (also known as Orhan I or Orhan Bey), who reigned from AD 1324 to AD 1361 (Kuran 1968). The actual date of the original construction of this building is not known; surviving records give only the date of its reno - vation in AD 1775. It is believed, however, that the Orhan Gazi mosque was built slightly after the Ottoman conquest of Constantinople (now Istanbul) in AD 1453, at the time when the famous cathedral of Hagia

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FIGURE 1 Location of Istanbul, Turkey, and Sarajevo, Bosnia-Herzegovina (Source: Google Earth) Sophia was converted into a mosque. According to Kuran (1968), the Orhan Gazi mosque was likely built in the early 15th century, based on the coarse rubble stones used in the structure and the lack of brick. These stones, along with Byzantine elements such as column capitals and bases, suggest a date during the early 1400s. The Orhan Gazi mosque has a dome and square walls, with a minaret at the east wall, adjacent to the building’s north entrance. The main dome has a radius measuring 6.15 m, and the walls of the square element are 9.55 m high. The total building height is 15.70 m. The dome is supported by four arches, 1.15 m thick, enclosed by the building wall. There are 23 windows in the building’s walls, aligned in

Minaret

Mihrab

Prayer hall

Minaret Entrance Entrance Prayer hall Mihrab

FIGURE 2 Plan (left) and section (right) of Orhan Gazi mosque FIGURE 3 (drawn by Mohamad Nazri Radzi, Research Assistant, Orhan Gazi mosque Universiti Sains Malaysia) (photo by Kasim Oktay)

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) 168 Ahmad Sanusi Hassan and Yasser Arab four tiers. The mihrab is located in a niche at the south wall. The Ferhadija mosque (see Figures 4 and 5) was built in AD 1560 and is named for Ferhad Bey, the Bosnian governor who commissioned the structure. The style of this mosque is atypical of Ottoman architecture in Bosnia. The building has features typical of a single-dome pendentive plan, Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 including a round dome covering the interior prayer hall and three small semi-circular domes covering a riwaq area. Its design is influenced by the Ottoman style; it includes porticoes with small domes, a minaret attached to a perimeter wall, and a pendentive round dome used as a roof cover. Like the Orhan Gazi mosque, it has a dome and square wall construction. Its minaret is located on the west side of the building entrance. The mosque’s dome measures 5.45 m in radius; the square walls are 10.9 m × 10.9 m (Mujezinovic 1998 ). A mihrab is located at the south wall. Rubble stones are laid in a brickwork-like pattern throughout the walls.

Minaret

Prayer hall Entrance Mihrab

Prayer hall Minaret Entrance Mihrab

FIGURE 4 FIGURE 5 Plan (left) and section (right) of Ferhadija mosque Ferhadija mosque (photo by Ahmad (drawn by Mohamad Nazri Radzi, Research Sanusi Hassan) Assistant, Universiti Sains Malaysia)

The Simulation Method

Our purpose in this survey was to simulate the indoor lighting perfor - mance of the two mosques and to compare the results. This simulation (see Figure 6) was conducted on 21 June 2011 on the summer solstice when the sun’s path was at a perimeter along the Tropic of Cancer. This daylight simulation analysis employs a computer-based calculation of the amount of daylight inside the building using Autodesk 3ds Max Design 2012. Before the simulation analysis was conducted, three-dimensional drawings of the two mosques, based on 1:1 measured illustrations, were created using AutoCAD.

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FIGURE 6 Lighting simulation in 3ds Max Design 2012 These three-dimensional models were then imported into 3ds Max Design 2012. A daylight system can be created in this program; the camera view must be set to the top view (perspective) before the lighting analysis can be generated. A specific local daylight system was inserted using available weather data for Sarajevo and Istanbul, downloaded from weather data files (*.epw) (U.S. Department of Energy 2010) and containing an average of 30 years’ annual data for each city. A light meter was created by setting points of incidence that show the illuminance level. Each subdivision represents a point at which incident illu - minance was represented by the grid size of 0.5 m × 0.5 m and would be measured (calculated). This method provides an overlay grid of illuminance results. The simulation was created after identifying a light meter at human

5 5

1 2 3 1 2 3

N N OrhanOrhan GGaziazi MosqueMosque FerhadijaFerhadiijja MosqueMosque

FIGURE 7 Location points 1, 2, 3, 4, and 5 of the simulation

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TABLE 1 Measurable scale of indoor lighting performance Scale level Illuminance Level (lx) Illuminance Level (brightness)

0 0–20 Total darkness to very dark for tasks that do not require high visibility Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 1 20–49 Slightly dark for tasks that do not require high visibility

2 50–99 Slightly not to the brightness suitable for tasks that do not require high visibility 80–199 Brightness suitable for tasks that do not require high 3 visibility (rooms not in permanent use; hallway brightness) 4 200–499 Brightness suitable for reading areas like office, classroom and library 5 500–999 Details are difficult to see for intricate work 6 1 000–1 999 Task lighting for highly demanding work—extremely fine details (e.g., microelectronic assembly) 7 2 000–10 000 Task lighting for highly demanding work—extremely fine details (e.g., special tasks in surgery) 10 000 lx is maximum brightness from sunlight to indoor 8 area 10 001–100 000 Outdoor area brightness 100 000 lx is the maximum measurement

body level (when sitting on the floor praying and listening to the Friday sermon), 450 mm above the floor level of the mosque. The results are based on this light-meter setting, with modification to match the selected weather file (Landry and Breton 2009). Selected points on the imaginary grid plan layouts are used in this simulation. The duration of the simulation is limited to 12 hours, with measurements taken at one-hour intervals from 6:00 am to 6:00 pm on 21 June 2011. The simulation does not take the time of sunrise and sunset into account when collecting measurements. Each hour is repre - sented by a lighting analysis calculation per frame in one rendering image at a resolution of 1024 × 768 pixels. This analysis is meant to test indoor illumi - nance levels by reproducing atmospheric conditions from the weather-file data at five selected points (P1 = entrance door; P2 = centre of prayer hall; P3 = mihrab ; P4 = right/east side of prayer hall; and P5 = left/west side of prayer hall) inside each mosque (see Figure 7). The results for each point are collected, and the data are then converted to tables and line graphs. These results allow us to perform a comparative analysis of lighting performances between the two mosques. This analysis refers to measurable scales (see Table 1) that recommend ranges of minimal illuminance levels (Schlyter 2009; Wikipedia 2010; Krochmann et al. 1989).

Results

The results of the simulation are illustrated in Tables 2 and 3 and Figures

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TABLE 2 Indoor lighting performance (lx), Ferhadija mosque, 21 June 2011

6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

P1 251 300.5 334.8 401.3 480.9 455.1 447.5 479.7 445.8 364.2 373.1 317.1 91.1 Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021

P2 178.2 263.9 284.2 312.5 328 307.3 280.8 295.9 275.8 235.3 185.9 132 45.4

P3 104.1 166 218.4 201.6 194.9 163 146 156.1 148 129.2 114 73.1 23.8

P4 115.9 165.4 191.3 217.1 223.8 206 194.5 211.4 210.4 171.7 142.8 97.5 31.9

P5 140.5 174.5 201.9 214.2 228.5 217 187.1 199.1 202.5 185.5 165.1 104.7 35.1

TABLE 3 Indoor lighting performance (lx), Orhan Gazi Mosque, 21 June 2011 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

P1 399 663 687.3 677.2 670.8 653 664.1 682 751.6 825.1 952.5 638.3 220.3

P2 70.3 137 158.1 177.1 187.1 174.6 186 168.2 212.8 193.8 142.2 96.9 31.3

P3 56 80.2 106 180.8 145.9 117.6 121.6 140 143.4 153.2 115.8 75.4 23.6

P4 320.5 204.4 166.7 193.3 180.1 155.3 184.8 160 142.3 147 126.4 100 30.3

P5 73.7 137.3 156.7 148.3 154.2 114.8 121.3 103.5 100.1 107.6 84.4 61.1 23.1

FIGURE 8 Illuminance levels at Point 1

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8–12. The analysis consists of a comparative study of the Orhan Gazi and Ferhadija mosques by reference to the results of the simulation.

Point 1 Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 Figure 8 shows illuminance levels at Point 1 (north location, near the mosque entrance) for both mosques. Point 1 is brighter than the other locations measured: P1 illuminance levels at Orhan Gazi and Ferhadija range from lows of 220 and 91 lux (lx) at 6:00 pm to highs of 953 lx at 4:00 pm and 481 lx at 10:00 am, respectively. The average illuminance level is higher at Orhan Gazi (653 lx) than that at Ferhadija (365 lx). In Orhan Gazi, sunlight from 7:00 am to 5:00 pm provides illuminance levels >630 lx, equivalent to level 5 on the scale shown in Table 1; Orhan Gazi has higher illuminance levels than Ferhadija throughout the simulation, from 6:00 am to 6:00 pm, and shows good illuminance levels, >200 lx (level 4), at all times. Ferhadija has good illuminance levels (>200 lx, level 4) from 6:00 am to 5:00 pm; from 9:00 am to 2:00 pm, the illuminance level is >400 lx. At 6:00 pm, however, the illuminance level at P1 in Ferhadija is <200 lx (level 3).

Point 2

Figure 9 illustrates illuminance levels at Point 2 (central prayer hall). At P2, unlike at P1, Orhan Gazi is not brighter than Ferhadija Mosque throughout the day; instead, Ferhadija Mosque has relatively higher illu -

FIGURE 9 Illuminance levels at Point 2

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) Lighting Analysis of Single Pendentive Dome Mosque Design 173 minance levels than Orhan Gazi Mosque at all times. At P2, illuminance levels at Orhan Gazi and Ferhadija range from lows of 31 and 45 lx at 6:00 pm to highs of 213 lx at 2:00 pm and 313 lx at 9:00 am, respectively. The average illuminance level is lower at Orhan Gazi (149 lx) than at Ferhadija (240 lx). In Orhan Gazi, sunlight from 10:00 am to 3:00 pm provides illu - Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 minance levels >180 lx, equivalent to levels 3 and 4 on the scale in Table 1. Its lowest level was measured at 2:00 pm (213 lx, equivalent to level 2). Unlike at Point 1, the indoor lighting performance at Ferhadija is better than that at Orhan Gazi. At Orhan Gazi, illuminance levels from 7:00 am to 5:00 pm range from 97 to 200 lx (level 3), except at 6:00 am (70 lx; level 2) and 2:00 pm (213 lx; level 4). At Ferhadija, on the other hand, illuminance levels are good (>200 lx; level 4) from 7:00 am to 3:00 pm; simulations at 6:00 am, 4:00 pm, and 5:00 pm show illuminance levels of 178, 186, and 132 lx respectively (level 3). At 6:00 pm, P2 in Ferhadija Mosque has an illuminance reading <80 lx (level 2).

Point 3

Figure 10 shows illuminance levels at Point 3 (a southern location near the mihrab ). Illuminance levels at P3 are lower than at any other location, ranging from a low of 24 lx at 6:00 pm to highs of 218 lx at 8:00 am and 181 lx at 9:00 am at Orhan Gazi and Ferhadija respectively. The average illuminance level for P3 is higher at Orhan Gazi (112 lx) than at Ferhadija (141 lx). In Orhan Gazi, sunlight provides illuminance levels of only 2 and 3; the highest illuminance is 181 lx. Orhan Gazi has lower illuminance levels than Ferhadija throughout the simulation, except from 3:00 pm to

FIGURE 10 Illuminance levels at Point 3

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FIGURE 11 Illuminance levels at Point 4

5:00 pm. Orhan Gazi’s illuminance levels from 7:00 am to 4:00 pm are >80 lx (level 3); from 9:00 am to 10:00 am and from 1:00 pm to 3:00 pm, Orhan Gazi has illuminance levels ranging from 140 to 181 lx. Ferhadija has slightly higher illuminance levels from 6:00 am to 4:00 pm, >100 lx (level 3–4). From 8:00 am to 9:00 am (morning sunlight), Ferhadija’s illu - minance levels are >200 lx. Illuminance levels at P3 are <80 lx (level 2) only from 5:00 pm to 6:00 pm for both Orhan Gazi and Ferhadija and at 6:00 am for Orhan Gazi. Point 4

Figure 11 illustrates illuminance levels at Point 4 (near the west wall). At P4, Ferhadija is brighter than Orhan Gazi in most simulations made from 6:00 am to 6:00 pm; the only exception is 6:00 am. Illuminance levels at Orhan Gazi and Ferhadija range from lows of 30 and 32 lx at 6:00 pm to highs of 321 lx at 6:00 am and 223.8 lx at 10:00 am, respectively. At P4, the average illuminance level was slightly lower at Orhan Gazi (162 lx) than at Ferhadija (168 lx). At Orhan Gazi, sunlight from 6:00 am to 7:00 am, from 9:00 am to 10:00 am, and at 12:00 pm provided illuminance levels >180 lx, equivalent to levels 3 and 4; only at 6:00 am did P4 show an illu - minance level equivalent to level 2 (321 lx). Unlike at P1, indoor lighting performance is better at Ferhadija than at Orhan Gazi. Ferhadija showed higher brightness levels than Orhan Gazi throughout all simulations from 7:00 am to 6:00 pm. At P4, Orhan Gazi has illuminance levels of 100–193 lx (level 3) from 8:00 am to 5:00 pm; of 30 lx (level 2) at 6:00 am; and level 4 from 6:00 am to 7:00 am. Ferhadija, on the other hand, has

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FIGURE 12 Illuminance levels at Point 5 more evenly distributed illuminance levels, with level 4 from 9:00 am to 11:00 am and from 1:00 pm to 2:00 pm. At all other time points, the simu - lation recorded illuminance levels at level 3, except at 6:00 pm, with an illuminance level of 32 lx (level 2).

Point 5

Figure 12 shows illuminance levels at Point 5 (location near east wall) for both mosques. At P5, Ferhadija had higher brightness levels than Orhan Gazi during the simulation. The lowest illuminance levels at Orhan Gazi and Ferhadija were 23 and 35 lx respectively, both at 6:00 pm; the highest levels were 157 lx at 8:00 am and 229 lx at 10:00 am, respectively. The aver - age illuminance level is lower at Orhan Gazi (107 lx) than at Ferhadija (174 lx). At Orhan Gazi, sunlight provides illuminance levels equivalent to level 3 from 7:00 am to 4:00 pm; at Ferhadija, sunlight provides illumi - nance levels equivalent to levels 3 and 4 from 6:00 am to 5:00 pm. At P5, Orhan Gazi has lower illuminance levels than Ferhadija throughout all simulations made from 6:00 am to 6:00 pm. The ranges of illuminance levels from 7:00 am to 4:00 pm were 160–230 lx for Ferhadija and 60–121 lx for Orhan Gazi. Ferhadija has good illuminance levels (200 lx; level 4) from 8:00 am to 11:00 am and at 2:00 pm; only at 6:00 pm was there a reading <80 lx (level 2).

Discussion

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FIGURE 13 Illuminance levels at Ferhadija mosque, Points 1–5 This study documents maximum illuminance levels based on lighting simu - lations of pendentive-dome mosques with data on brightness levels (during summer solstice). The interior lighting is important in creating a sense of sacredness within a place of worship. The pendentive-dome design provides interior illuminance levels equivalent to level 3 or 4 at most time points between 6:00 am and 6:00 pm. At no point in did the simulations record illu - minance levels <20 lx (level 0). The findings of our comparative analysis can be summarized as follows (see Figures 13 and 14): 1 Ferhadija has better illuminance levels at Points 2–5, as recorded throughout the simulations. Most illuminance levels >200 lx (Scale 4) are at P1 and P2 at Ferhadija and P1 at Orhan Gazi. 2 Maximum brightness levels at Ferhadija are 481 lx (10:00 am) at P1, 313 lx (10:00 am) at P2, 218 lx (8:00 am) at P3, 224 lx (10:00 am) at P4, and 229 lx (10:00 am) at P5; maximum brightness was recorded mostly around 10:00 am. 3 Maximum brightness levels at Orhan Gazi are 953 lx (4:00 pm) at P1, 213 lx (2:00 pm) at P2, 181 lx (9:00 am) at P3, 204 lx (7:00 am) at P4, and 157 lx (8:00 am) at P5, occurring mostly in early morning and evening. 4 As Figures 13 and 14 show, both mosques have higher illuminance levels at P1 than at P2–P5. P1 at Orhan Gazi recorded higher illuminance levels than P1 at Ferhadija. At both Ferhadija and Orhan Gazi, P2 ranks second, followed by P4 and P5, while P3 has the lowest ranking. 5 Large door openings for entrances at both mosques are an important factor in the high illuminance recorded at P1. Orhan Gazi has a higher illuminance level at P1 because, unlike Ferhadija, it does not have a

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) Lighting Analysis of Single Pendentive Dome Mosque Design 177 Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021

FIGURE 14 Illuminance levels at Orhan Gazi mosque, Points 1–5

riwaq (entrance corridor); as a result, P1 is exposed to unobstructed daylight. In addition, the southern source of sunlight provides addi - tional illuminance at P1, an area near the mosque’s entrance. 6 The upper window openings built around the dome’s perimeter provide daylight at P2, the central prayer hall. This shows the impact of the pendentive-dome design on levels of illuminance at P2 in both mosques. 7 Based on the results of the simulation, we conclude that the pendentive- dome design used at Ferhadija is more efficient than the designed used at Orhan Gazi. Ferhadija’s height:width ratio is 1.47, compared with 1.21 at Orhan Gazi; this means that the larger the ratio of height to width, the higher the illuminance level in the central prayer hall. Further study is needed to identify the maximum and minimum ratios necessary to create optimal illuminance inside the mosque.

Conclusion

This study concludes that the single-pendentive-dome design brings addi - tional brightness into the mosque’s central prayer hall from outside sunlight. The design takes advantage of additional sunlight by means of the upper openings at the roof. This daylight penetration helps provide evenly distributed illuminance levels at all locations inside the mosque, thus giving additional interior brightness. Using this pendentive roof form, the master builders were able to design mosques with excellent natural lighting, with light entering the mosque at various angles from the roof perimeter. The pendentive-dome design creates a vast, light-filled

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) 178 Ahmad Sanusi Hassan and Yasser Arab interior space free of obstructions such as walls or columns (Goodwin 1993), with upper and lower window openings designed to transmit a certain amount of daylight into the prayer hall at brightness level 3 or 4. This offers the master builders the chance to explore lighting design as a source of expression leading toward a sense of worship, with the presence Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 of divinity inside the heritage building.

Acknowledgements This study was complete with the assistance of a Research University Grant at the Universiti Sains Malaysia. The authors especially thank Assoc. Prof. Dr. Spahic Omer, co-researcher on the Bosnian side, for his assistance in providing research materials and information.

References Chel, A., Tiwari, G. N., and Chandra, A. 2009. A modified model for estimation of daylight factor for skylight: An experimental validation using pyramid shape skylight over vault roof mud-house in New Delhi (India). Applied Energy 86:2507–19. Chel, A., Tiwari, G. N., and Singh, H. N. 2009. A modified model for estimation of daylight factor for skylight integrated with dome roof structure of mud- house in New Delhi (India). Applied Energy 87:3037–50. Goodwin, G. 1993. Sinan Ottoman architecture and its values today . London: Saqi. Hassan, A. S., and Mazloomi, M. 2010a. The importance of plan unit design with reference to pendentive dome mosque architecture in Early Ottoman period in Balkan region and Anatolia. Review of European Studies 2(2):105–16. ———. 2010b. Sectional analysis of pendentive dome mosques during Ottoman Era. Canadian Social Science 6(5):1–9. Hillenbrand, R. 1994. Islamic architecture: Form, function and meaning . Edinburgh: Edinburgh University Press. Krochmann , J., et al. 1989. The measurement of luminous flux . Vienna: CIE Central Bureau. Kuran, A. 1968. The mosque in early Ottoman architecture . Chicago: University of Chicago Press. Landry, M., and Breton, P. 2009. Daylight simulation in Autodesk 3ds Max Design 2009: Advanced concepts . Denver, Colorado: Autodesk Inc. Mango, A. C. 1976. Byzantine architecture . New York: Abrams. Mujezinovic, M. 1998. Ferhadija Džamija [Ferhadija Mosque]. In Islamska epigrafika Bosne e Hercegovine [Islamic epigraphy in Bosnia-Herzegovina] , vol. 1. Sarajevo: Sarajevo Publishing. Necipoglu, G. 2005. The age of Sinan: Architectural culture in the Ottoman Empire. In Muqarnas: An annual of visual culture of the Islamic world, ed. G. Necipoglu, 141–84. London: Reaktion. Pasic, A. 2004. A short history of Mostar. In Conservation and revitalisation of

The Arab World Geographer / Le Géographe du monde arabe Vol 15, no 2 (2012) Lighting Analysis of Single Pendentive Dome Mosque Design 179

historic Mostar . Geneva: Aga Khan Trust for Culture. Runsheng, T., Meir, I. A., and Etzion, Y. 2009. An analysis of absorbed radia - tion by domed and vaulted roofs as compared with flat roofs. Energy and Buildings 35(6 ):539–48. Saoud, R. 2004. Muslim architecture under Ottoman patronage . Manchester: FSTC Limited. Downloaded from http://meridian.allenpress.com/awg/article-pdf/15/2/163/1448500/arwg_15_2_m0g8207v8222723x.pdf by guest on 30 September 2021 Schlyter, P. 2009. Radiometry and photometry in astronomy. Stockholm. http://www.stjarnhimlen.se/comp/radfaq.html#10 SunriseSunset.com. 2012. Calculate sunrise and sunset times for any location. http://sunrisesunset.com U.S. Department of Energy. 2010. EnergyPlus energy simulation software: Weather data. http://www.eere.energy.gov/buildings/energyplus/ cfm/weather_data.cfm Wikipedia. 2010. Lux measurement. http://www.en.wikipedia.org/ wiki/Lux#cite_note-3

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