Optimizing Daylighting Typology in Religious Buildings: A Case Study of Electrochromic Glazing Integration in the Masjid Al-Shagroud

Abstract

Mosques, revered as sacred spaces, are distinguished by their sustainable architectural designs. A critical aspect of these designs is the implementation of daylighting strategies, essential for ensuring adequate light levels, particularly for reading the Holy Quran. Traditional daylighting typologies in mosques, such as multi-lateral lighting, clerestories, skylights, and shading devices, are widely recognized. However, the potential application of electrochromic (EC) switchable glazing within mosque architecture remains underexplored. This study delves into the effectiveness of various daylighting typologies, assessing their performance before and after the integration of EC switchable glazing in the Al-Shagroud Mosque located in Saudi Arabia. Employing comprehensive radiance simulations in accordance with the LEEDv4.1 standards, the study evaluates additional metrics including useful daylight illuminance (UDI_{300–3000lux}), workplane illuminance (WPI), uniformity index (Ui), and daylight glare probability (DGP) under multiple scenarios. The results demonstrate that clerestory lighting effectively meets LEEDv4.1 benchmarks but exhibits limitations in achieving uniform light distribution, particularly in the men’s prayer hall. In contrast, the women’s prayer hall benefits from a combination of clerestory lighting and shading devices, which improves light quality and mitigates glare issues. However, the use of skylights without adequate shading leads to excessive WPI and high DGP levels, compromising visual comfort. Moreover, managing daylight quantity and quality through the integration of different typologies, including hybrid models, presents substantial challenges. The integration of EC switchable glazing, while maintaining optimal WPI and reducing DGP, offers enhanced visual comfort in prayer areas. Nevertheless, this technology faces difficulties in ensuring even light distribution, as evidenced by lower uniformity index values. This research highlights the critical need for optimizing daylighting in mosques to balance sustainability and comfort, without detracting from their sacred ambiance.

1. Introduction

The development of built environments prioritizes the facilitation of human comfort, which encompasses thermal, acoustic, visual comfort, and indoor air quality [1]. Visual comfort specifically balances light levels to prevent discomfort from insufficient or excessive illumination. The role of daylight is pivotal in achieving visual comfort and optimizing environmental efficiency within a space [2]. The architectural discourse has shown a heightened interest in the practical and aesthetic applications of natural light. Typology is an essential methodological tool for discerning the unique characteristics and spatial geometry of the built environment [3,4], deeply influencing daylight distribution [5]. It necessitates a thorough spatial analysis to understand how architectural elements such as orientation and their configurations impact the penetration and diffusion of daylight. Proper orientation not only maximizes natural light but also reduces energy consumption by minimizing the need for artificial lighting, ultimately enhancing sustainability and comfort within the built environment [6,7], as orientation influences the intensity and angle sunlight, thus affecting the quantity and quality and distribution of daylight within the space. This analysis is critical in optimizing the use of natural light within buildings, informing design decisions that align with both functional and aesthetic goals.

In the context of spiritual architecture, the design of lighting [8], particularly daylighting, is intricately tailored to fit the distinct spiritual practices and liturgical needs within sacred spaces like mosques and churches [9]. For mosques, this involves careful consideration of the multifunctional prayer hall, central to Islamic worship, community interaction, and religious teachings [10]. The typology of mosques ranging from the large, community-serving Masjid Al-Jami to the smaller, local Masjid Al-Hayi—is integral in defining the requisite quality of daylight that aligns with worship practices [11]. While existing studies have explored the role of daylight in sacred spaces, most have not thoroughly integrated spiritual considerations with the quantitative and qualitative analysis of daylight. For instance, research has compared the spatial and daylighting dynamics in Byzantine churches and Ottoman Mosques [12], while others have focused on the illuminative effects of specific architectural elements like mosque domes [13]. However, these findings are often not generalizable across different typologies. This study aims to investigate deeper into the typological analysis to assess visual comfort within mosques, exploring how sensory and contextual factors affect daylight distribution and its contribution to spiritual ambiance. It addresses the gap in understanding how various mosque daylighting typologies influence visual comfort, analyzing daylight performance in diverse mosque designs to evaluate the visual comfort levels of worshippers.

1.1. Daylighting Typologies in Mosques

Daylighting typologies in mosques manifest through various architectural features, each contributing uniquely to the internal luminosity and ambiance of the worship space. Skylights, for instance, are a common feature, often incorporated within the dome structure, allowing vertical penetration of light that enhances the spiritual and aesthetic qualities of the space. The shape of these skylights, sometimes round to echo the celestial bodies or geometric to reflect Islamic patterning, is designed to capture and funnel light directly downwards [14]. Their position at the apex of the dome ensures that when the sun is at its zenith, the light is distributed evenly across the central area, often over the Mihrab, which holds significant religious importance as it not only indicates the direction of Qibla (guiding worshippers in their prayers), but also serves as the focal point for the congregation during prayers [4]. Clerestory lighting involves windows that are placed high on the walls, above eye level, which allows for both privacy and light. The positioning of clerestory windows is crucial; they are often aligned with the cardinal directions to capture the optimal quality of light throughout the day. In terms of shape, they can range from simple, clear openings to intricately designed stained glass that diffuses the light into the prayer space. The position of these windows outside the direct line of sight of mosque visitors can mitigate or eliminate glare, particularly during periods of low solar altitude angles, such as the winter solstice, in spaces with conventional window placement [7]. Side lighting is used to introduce light through windows at or near the worshipper’s eye level. The shape of side windows can vary, from arched to pointed, and their positioning on the wall is critical for controlling the amount and direction of light entering the space [15]. Bilateral [16] and multi-lateral lighting approaches further refine the quality of light by introducing multiple light sources from various orientations, thereby ensuring a more uniform distribution of light and reducing the contrast between illuminated and shadowed areas. The illustration in Figure 1 provides a three-dimensional cross-section of mosque architecture for each daylighting typology.

1.2. Dynamic Glazing System

Dynamic glazing systems are pivotal in modern architectural design and cities, offering tailored control over light and heat entering a building [15,17]. There are several types of dynamic glazing systems, such as thermochromic [18], suspended particle device (SPD) [19], photochromic [20], and liquid crystal glazing (PDLC) [21]. Among these, electrochromic (EC) glazing stands out for its capacity to fine-tune daylight usage and improve visual comfort [22,23]. These innovative systems adapt their optical properties to balance solar heat gain and minimize glare, thus maintaining a regulated indoor environment that still preserves visual access to the outdoors. Specifically, EC glazing changes its shade to manage the indoor illuminance in response to external sunlight intensity and internal demands, enhancing energy efficiency and the comfort of occupants. The mechanism of EC glazing operates by applying a low-voltage electrical current which triggers a reversible change in the optical properties of the glass, transitioning from transparent to tinted states. This transition allows for precise control over the amount of light and heat passing through, based on real-time environmental conditions and occupant preferences [24,25]. This technology is particularly beneficial in spaces such as mosques, where the interplay of light is crucial to the spiritual and aesthetic ambiance. Incorporating EC glazing into mosque architecture can revolutionize environmental control, supporting sustainable building practices while upholding the tranquil and sacred atmosphere of the prayer areas. A hypothetical presentation of daylight penetration of different EC glazing states is depicted in Figure 2.

Studies evaluating the performance of EC glazing in buildings from a daylighting perspective affirm its substantial benefits. Research has demonstrated that EC glazing can significantly reduce energy consumption for artificial lighting and cooling, leading to improved thermal and visual comfort levels within interior spaces. For example, Cannavale et al. (2020) confirms this by demonstrating how smart EC glazing windows can lead to marked energy savings by reducing reliance on artificial lighting and climate control systems [22]. Lee and Tavil (2007) provide evidence that the strategic combination of electrochromic windows with overhangs can result in improved energy efficiency and visual comfort through optimized daylight use and minimized solar heat gain [26]. Further supporting these findings, Fernandes, Lee, and Ward (2013) illustrate that split-pane electrochromic windows, managed for daylighting while maintaining visual comfort, offer substantial energy savings in lighting without compromising occupant comfort [27]. Mardaljevic et al. (2008) confirmed that EC windows could improve UDI which is enhancing occupant satisfaction with the indoor lighting environment; they also found that the EC glazing provides the greatest energy benefit for those cases of integrating photovoltaics (PVs) into opaque vertical facades at the lower end of the experienced range in total annual vertical irradiation [28]. Collectively, these studies and

Table 1. An overview on quantitative and qualitive research on the integration of EC glazing in buildings.

Author(s) and Year	Type of Analysis	Key Findings	Limitations
Kheira Anissa Tabet Aoul et al. (2019) [29]	Quantitative	EC glazing can reduce electricity demand by 7–16%, with potential savings based on building type and window size. Hybrid EC windows with PV cells offer additional benefits.	Need for extensive research on design, energy, and cost-saving benefits; evaluation of hybrid EC and PV windows.
Rickard Tällberg et al. (2019) [30]	Quantitative	Electrochromic window controlled by operative temperature shows highest potential in lowering energy demand across different locations.	Effective control strategies required to maximize benefits; comparison across diverse climatic conditions needed.
N. Aste, F. Leonforte, A. Piccolo (2018) [31]	Qualitative and quantitative	Studied color rendering of smart glazings and its effect on occupants’ perception of interior spaces, highlighting the impact on aesthetic and comfort.	Challenges in balancing the color-rendering capabilities of smart windows with their energy-saving performance.
Joud Al Dakheel, K. T. Aoul (2017) [32]	Quantitative	Electrochromic glazing is the most applied smart glazing due to extensive glass use in buildings, saving from 12 to 50% of building cooling electricity consumption.	High initial cost, maintenance requirements, and need for specialist installers.
B. P. Jelle et al. (2013) [33]	Quantitative	Low-thermal transmittance and potential for daylight and solar energy utilization highlighted in fenestration products including electrochromic windows.	Need for further advancements in vacuum glazing and hybrid technologies for improved performance

reinforce the notion that EC glazing is a potent tool for enhancing the quantitative and qualitative aspects of building performance, aligning with broader sustainability goals in the built environment sector.

In the context of mosques, which are architectural embodiments of spiritual and cultural expression, the incorporation of EC glazing can be particularly advantageous. The deployment of EC glazing in mosques can harmonize daylighting with spiritual functions, allowing for an ambient light quality that supports focus and introspection. For instance, during peak daylight hours when glare could be most disruptive, EC glazing can adjust to soften the light, thus maintaining the visual connection with the outdoors while ensuring a glare-free environment conducive to prayer and contemplation and reading the holy Quran. Furthermore, it can enhance the energy efficiency of these structures, reducing reliance on artificial lighting, and thereby aligning with Islamic principles of stewardship towards the environment.

1.3. Related Works

A systematic literature review synthesizes findings from recent studies focused on the daylighting performance in mosque architecture, particularly emphasizing design strategies, methods of evaluation, and the results obtained with respect to daylighting metrics.

Rodzi et al. (2022) set out to assess the sustainability of a mosque design proposal, with a strong emphasis on design features that promote environmental and energy performance. Their method was primarily evaluative, based on design analysis, without an in-depth focus on daylighting metrics [34]. Moghaddasi et al. (2021) approached mosque lighting from a historical perspective, detailing the innovations in mosque lighting techniques within Iran, and their methods were largely qualitative, based on historical analyses [35]. In a more quantitative vein, Arab and Hassan (2013) examined the daylight performance of a mosque design with a single pendentive dome during the winter solstice, using daylight simulation tools to analyze spatial daylight autonomy (sDA) and annual sunlight exposure (ASE) [36]. Sanusi et al. (2021) explored effective daylight design strategies in colonial mosques, using case study analysis methods to qualitatively describe the daylighting strategies but not quantifying their performance [37]. Hareri and Alama (2020) compared the lighting designs of two mosque typologies in Jeddah, with a focus on the qualitative evaluation of design elements that influence natural light distribution [38]. Shahani (2018) narrated the interplay of daylight within sequential spaces of the Sheikh Lotfollah Mosque, applying a descriptive approach without employing empirical daylighting metrics [39]. El-Darwish and Gendy (2016) highlighted the significant role of fenestration in mosque designs in Alexandria since the 19th century to enhance daylight performance, a comparative study of six mosques typologies through the daylight autonomy as an annual daylighting metric [40]. Wardono and Wibisono (2018) sought to link daylight with meditative experiences in mosques, presenting a theoretical discourse rather than empirical measurement [41]. Moving towards a comparative approach, Pamuk et al. (2020) analyzed the daylight performance of Konya mosques across historical periods, utilizing in situ measurement and daylight simulation using Autocad software to assess the workplan illuminance level distribution [42]. Belakehal et al. (2016) considered daylight a crucial design element in the Ottoman mosques of Tunisia and Algeria. Their study provided a comprehensive understanding of the historical value of daylighting strategies based on typological, topological, and morphological analysis but fell short of offering quantitative results [43]. Investigations into the dome skylight’s attributes and their semantic transparency have been prominent, with studies delving into the semantic interpretations of mosque components that contribute to a sense of centrality, contrast, continuity, and metaphorical expression within the sacred space [44]. Additional research has focused on the aesthetic and spatial qualities of mosque interiors, emphasizing simplicity, clarity, and purity of light as integral to the aesthetic experience [45]. Concurrently, other studies have addressed the uniformity of light in prayer halls, recognizing its substantial influence on spatial perception [7]. The spiritual and psychological impacts of daylighting have also been subjects of scholarly attention, acknowledging the significant correlation between light quality and worshippers’ reflective perceptions and comfort levels [8].

Various daylighting parameters, such as daylight factor, autonomy, annual daylight, useful daylight illuminance, light distribution, and daylight glare probability, have been meticulously examined across different studies, advancing our understanding of the interaction between light and spirituality. For instance, Matracchi and Habibabad’s simulation of the light intensity in Shiraz’s Nasir al-Mulk Mosque illuminated the profound effects of light on spirituality [8], while photometric analyses in the Shahrek-e-Gharb Mosque highlighted consistent yet subdued lighting conditions within the vault, excluding the Mihrab [46]. Further research by Tarabieh et al. applied space syntax theory, utilizing Radiance and Daysim within Rhino 7 software simulations, to quantify the comprehensive perception of space influenced by comfort, environmental, and proximity parameters for observers [47]. Additionally, the quest for sustainable lighting solutions was exemplified in Atlgan and Enarun’s development of an energy-efficient LED lamp designed to augment the illumination of traditional Turkish mosques [48]. Through the utilization of Diva for Rhino, Darwish and El-Gendy assessed daylighting in Alexandrian mosques, evaluating whether they achieved the necessary illumination and glare standards [40].

1.4. Research Gap and Contribution

To ascertain the level of scholarly interest in the study of daylighting strategies within mosque architecture, as well as the implications of incorporating smart glazing systems in such architectural contexts, a comprehensive bibliometric analysis was conducted utilizing keyword-based searches in the Web of Science (WOS) database spanning the years from 2000 to April 2023. The resulting dataset was then visualized using the VOS-viewer tool. In Figure 3, the bibliometric map provides insights into various sub-domains of research related to mosque daylighting typology and the adoption of smart window technologies within mosque structures. Notably, the size of each node on the map corresponds to the frequency of distinct keywords, while the distance between nodes reflects the degree of co-occurrence of keywords. Among these research sub-domains, the daylighting design and its performance [49,50,51,52] emerge as the most extensively investigated area. Following closely is the exploration of smart window technologies and their typologies [53], alongside inquiries into their optical and thermal properties and their integration within architectural settings. It is worth noting, however, that there is a noticeable limitation in terms of the co-occurrence of keywords related to mosques and the correlation between different daylighting typologies and the integration of smart windows within buildings, suggesting potential avenues for further exploration in this field.

The bibliometric analysis and review of related works reveals a substantial knowledge gap regarding the evaluation and integration of advanced daylighting technologies, such as smart switchable glazing, to address issues of glare and the distribution of daylight within mosque spaces. Specifically, there is a lack of research on the adoption of electrochromic glass and other smart glazing materials that dynamically control sunlight penetration year-round. This gap is pronounced in the context of hot regions, where such innovative strategies could mitigate the harsh effects of sunlight, optimizing both the daylight quantity and quality in mosque interiors. By addressing this gap, the study aims to provide a comprehensive examination of how the incorporation of EC glazing can enhance daylighting strategies in mosques. This involves a systematic exploration of the various daylighting typologies employed in mosque architecture and their compatibility with EC glazing technology. The research will assess the quantitative aspects of daylight, such as its intensity and distribution, to gauge the effectiveness of EC glazing in controlling sunlight penetration. This highlights an urgent need for research that not only considers traditional and passive daylighting strategies but also embraces these emerging technologies to enhance the environmental performance and user comfort in mosque designs suitable for hot climates.

2. Methodology

This research considers both qualitative and quantitative analyses of the simulation of different daylighting typology configurations integrated into the mosque such as multi-lateral lighting, clerestory, and skylight with and without shading devices. A comparative analysis mechanism is also applied to examine each scenario in both spaces (prayer man and women hall). The following sections present the simulation technique, the daylighting typologies scenarios used for the case study, and the assessment criteria implemented in this study.

2.1. Computer Simulation

Figure 4 depicts the methodological workflow in which ClimateStudio plugin tools LEED v4 (Leadership in Energy and Environmental Design) daylighting compliance, daylight availability, point in time illuminance, and radiance rendering are applied for visual comfort comparison and renovation of different daylighting strategy configurations in reference mosque. The LEED v4 compliance tool is particularly significant as it adheres to the latest standards set by the U.S. Green Building Council, ensuring that the design meets the daylighting criteria and contributes to the building’s overall certification process. The software simulates light behavior using Radiance; a physically-based engine developed and maintained by Lawrence Berkeley National Laboratory (LBNL). More importantly, ClimateStudio is validated based on the industry standard EnergyPlus and Radiance simulation engines and the results achieve a higher accuracy level than Daysim 4.1 software [54,55,56]. Rhinoceros, the popular 3D interface, serves as the geometrical platform in which the geometry can be easily visualized and internalized in ClimateStudio.

The simulation radiance parameters used in the daylighting simulation and material reflection are depicted in

Table 2. Material reflection used in radiance parameters of mosque structure.

Material	Reflection Coefficient (%)
Floor	60
Wall	80
Ceiling	80
DG-Glazing (Tvis)	77.4

. The radiance parameters such as ambient bounces, divisions, and accuracy were specified to ensure the photometric accuracy of the results as depicted in

Table 3. Radiance parameters used in daylighting simulation.

Radiance Parameter	Ambient Bounces	Ambient Divisions	Ambient Sampling	Ambient Accuracy	Ambient Resolution
Value	7	1500	100	0.1	300

.

2.2. Daylighting Typology Scenarios

This study mainly focused on the visual comfort of the Mosque (prayer hall of man and women) retrofitted with each of the eight scenarios (

Table 4. Scenarios of daylighting performance of prayer hall development used in simulation.

Scenario 1	Scenario 2	Scenario 3	Scenario 7 (Case Study)
Scenario 4	Scenario 5	Scenario 6

). As the disposition of opening (zenithal, lateral), size, dimensions, transparency of glazing, and design of these configurations needed to retrofitted to building fenestrations to achieve the daylighting quantity and quality requirements, the following daylighting strategy configurations (scenarios) were examined as depicted in Table 4.

1-

Multi-lateral lighting (Scenario 1): Scenario 1 is comprised only with several vertical openings on three sides (south–north axis and the eastern facade) of a men’s and women’s prayer hall with a window to wall ratio (WWR) of 40% in each side.

2-

Clerestory (Scenario 2): Scenario 2 is four rectangular openings placed on the upper side portion of the center of the men’s prayer hall in cardinal orientations with 10 m and 2 m length and height.

3-

Skylight (Scenario 3): Scenario 3 is a fully glass horizontal skylight lighting strategy integrated in the center of the mosque designed to capture illumination from the sky-dome and direct beam, with a 60% ratio from the roof area (dimension: 10 m, 10 m).

4-

Scenario (4, 5, and 6): This is the combination each of the previous scenarios with vertical fins in eastern and western facades connected with parallel frames in the top part of prayer halls.

5-

Hybrid typology (Scenario 7): Scenario 7 represents the case study in this research; the Alshaghroud Mosque is located on King Abdulla Road in the Taiba neighborhood of Dammam, in the eastern province of Saudi Arabia. The mosque covers an area of 1900 m² and can accommodate 2000 worshippers. The mosque has two floors, with the ground floor housing the main prayer hall, the entrance to the men’s prayer hall, the entrance to the women’s prayer area, ablutions, and toilets. The mosque hosts events to help people memorize the Holy Quran. The first floor, which is only a portion of the ground floor, is designated as a prayer hall for women and is accessible via stairs at the back of the main mosque. The entire mosque has been oriented toward the Qibla (western orientation). The geometric composition’s middle section, which runs parallel to the qibla wall, has been designed as a light filter (horizontal frames) that regulates the amount of daylight allowed through the skylight into the prayer hall. The mosque thus integrates three distinct daylighting strategies, correlating with the first three scenarios outlined previously, to achieve a harmonious balance between form, function, and spiritual ambiance.

6-

EC switchable glazing system (Scenario 8): Scenario 8 optimizes and retrofits the case study of the mosque with the electrochromic switchable glazing system with four tinting states through a daylighting control strategy applied to hybrid typologies; this scenario explores the optimization and retrofitting of a mosque by integrating an electrochromic switchable glazing system with four tinting states. Through a strategic daylighting control, applied to hybrid typologies, that would be a promising solution for improving the visual comfort.

2.3. Sun Path Condition

Sun path diagrams effectively illustrate the annual variations in the Sun’s trajectory. As shown in Figure 5, the midday sun in Dammam city is at a 40.54° solar altitude during the winter solstice and 86.12° during the summer solstice. These angles indicate a 45.5° deviation between the solstices because of the Earth’s declination, varying between −23° and +23° over the year. The solar energy incident on the southern and northern parts of the building is not the same since the southern side has better incident sunlight compared to the northern side. In contrast, considering the eastern and western directions, the incident solar energy exhibits symmetry. As a result, there should be a difference in the light distribution and intensity once daylighting strategy scenarios in the mosque are attached.

2.4. Modeling Approach and Analysis Criteria

The study’s modeling approach and analysis criteria can be categorized into two distinct methodologies: quantitative analysis and qualitative analysis.

The study employed quantitative analysis to transcribed workplane illuminance (WPI) values onto a tabulated format, focusing on the central grid positioned between bilateral windows on the south–north axis. Simulations were conducted for summer and winter solstices, as well as mid-season dates (21 June, 21 December), specifically at 12:30 p.m. and 3:30 p.m., coinciding with Duher and Aser prayer times. These periods were chosen to assess annual variations and critical times.

Simulation points (grids) within the prayer halls were arranged according to the layout of work planes, with a minimum of 225 points in the men’s hall and 60 in the women’s hall, all at a height of 0.30 m suitable for reading the holy Quran. The spacing between these points was maintained at 1.8 m for precision, as shown in Figure 6. A hemispherical fisheye camera (180°) was strategically placed at the center of each hall. The rendered images were presented in false color using a logarithmic scale for clarity.

The study also incorporated an evaluation of indoor visual comfort using the green building rating system, Leadership in Energy and Environmental Design (LEED v4.1). This standard focuses on two main metrics: spacial daylight autonomy (sDA_300lux) and annual sun exposure (ASE > 1000 lux, 250 h). The sDA_300lux metric assesses the percentage of an often-occupied floor area achieving the desired illumination levels (300 lux) under varying sky conditions throughout the year. The ASE_{>1000lux,250h} metric quantifies the proportion of regularly used floor space receiving direct sunlight (>1000 lux) for over 250 h annually. Additionally, the useful daylight illuminance (UDI) metric, with thresholds ranging from 300 lux to 3000 lux, was employed to effectively indicate high illumination levels that may cause discomfort glare and heat gains.

To further enhance the study, a modeling approach, qualitative analysis, and analysis criteria were introduced, focusing on an additional daylighting metric: daylight glare probability (DGP) [50,57]. DGP is a critical metric for assessing visual comfort in indoor environments, as it quantifies the likelihood of occupants experiencing glare due to high luminance ratios or bright light sources within their field of view. This metric is particularly relevant in spaces with large window areas or direct sunlight exposure. Incorporating DGP into the analysis provides a more comprehensive understanding of the daylighting quality, ensuring not just adequate illumination, but also comfort and wellbeing of the occupants. It is important to note that a comprehensive understanding of glare throughout the year can provide a more holistic view of the building’s performance. However, prioritizing summer analysis is a strategic decision that aligns with the peak conditions for sunlight exposure, ensuring occupant comfort and spiritual engagement during these significant times. This holistic approach to daylighting analysis, encompassing both quantitative and qualitative measures, aligns with the evolving standards of sustainable and human-centric design practices. Additionally, daylight distribution quality was measured using the uniformity index (Ui), a ratio of average to maximum illumination on the work plane, adhering to the NBN L13-001 code and international standards [35]. This index maintains a minimum threshold of 0.6. The criteria of assessments for each metric are summarized in

Table 5. Daylighting quantity and quality performance indicators used for mosque evaluation (reading Quran).

Criteria	Daylighting Performance Indicators
Quantitative
WPI	Setup from 300 lux to 1000 lux
sDA	300 lux for 50% of the occupied period
ASE	1000 lux or more for at least 250 occupied hours per year
UDI	300 lux < dark area (needs artificial light) In the range of 300–3000 lux (comfortable) at least 50% of the time Above 3000 is too bright with glare potential
Qualitative
Ui	Equal to or above 0.6
DGP	0.35 < imperceptible glare 0.35–0.40 perceptible glare 0.40–0.45 disturbing glare >0.45 intolerable glare

.

2.5. EC Glazing System Optimization

An electrochromic (EC) glazing system was selected for the optimization process, utilizing simulation data drawn from the International Glazing Database (IGDB) and verified with empirical data from the manufacturer, specifically Sage Glass. The system is capable of multiple transparency states, ranging from clear to fully tinted, including two intermediate states as outlined in Figure 7 and

Table 6. EC switchable glazing optical properties in each state.

EC States	Transmittance (Tvis) (%)		Reflectance (%)	SHGC (Unitless)
Transparent state	59.7		15.9	0.41
Intermediate tinted 1	17.3		10.4	0.15
Intermediate tinted 2	5.5		10	0.11
fully tinted	0.9		11.2	0.09

. The applied control algorithm adjusts the transmittance of the glazing; it reduces the light penetration to maintain interior illumination levels below 1000 lux or until the glass achieves its maximum tint level. The algorithm operates on an hourly basis throughout the year, targeting any occupied space within the building where direct sunlight exceeds 2% of the area, equating to illumination levels above 1000 lux sourced directly from the solar disc

3. Results and Discussion

3.1. Annual Daylighting Quantity of Prayer Zone

The data in

Table 7. Average annual results of CBDM and LEED v4.1 simulation for men’s prayer hall.

Scenarios (Men’s Prayer Hall)	LEED v4.1		UDI300–3000 lux (%)	WPI (lux)
	sDA300/50% (%)	ASE1000, 250h
Multi-lateral lighting (S1)	100	32.7	71.1	4196
Clerestory lighting (S2)	99.1	1.4	83.7	2224
Skylight (top lighting) (S3)	100	51.8	56.5	6970
Multi-lateral lighting +SD (S1)	100	24.5	86.2	2948
Clerestory lighting +SD (S5)	84.1	0.5	79.4	1373
Skylight (top lighting) +SD (S6)	87.7	32.7	70.3	3804
Hybrid typology (case study) (S7)	100	76.7	42.8	7631

delineate an intricate interplay among various daylighting strategies employed in the men’s prayer hall of a mosque in Lashari, Saudi Arabia, as evaluated through LEED v4.1, UDI_{300–3000lux}, and average WPI level. However, none of the scenarios meet all benchmarks. Starting with multi-lateral lighting, which emerged as the most efficacious, garnering a perfect sDA_300/50% score of 100% and yielding a moderate UDI_{300–3000lux} of 71.1%, this was at the risk of over-illumination with 32.7 ASE_1000,250h, an average lux of 4196 near the lateral window and low WPI in the center of the prayer hall. Clerestory lighting, despite its perfect LEED4.1 score of 99.1%, and an efficient annual sunlight exposer by only 1.4%, is the only typology achieved for this metric; also, a higher UDI_{300–3000lux} indicates the high efficiency of daylight quantity. Skylight strategies, although scoring high in sDA_300/50% and minimum UDI_{300–3000lux} metrics, were marked by an exorbitant average illuminance of 6970 lux and high ASE_1000,250h, signaling high issues with glare and thermal comfort. The introduction of shade devices (SD) generally curtailed LEED4.1 scores but tended to reduce both glare and overheating, as evidenced by lower ASE_1000,250h and UDI_{300–3000lux} metrics. Intriguingly, a hybrid approach combining all lighting methods and SD yielded the worst trade-off, minimizing UDI_{300–3000lux} at 42.8% while increasing the ASE_1000,250h to 76.8%, albeit at the highest lux level of 7631.

Table 8. Average annual results of CBDM and LEED v4.1 simulation for women’s prayer hall.

Scenarios (Women’s Prayer Hall)	LEED v4.1		UDI300–3000 lux (%)	WPI (lux)
	sDA300/50% (%)	ASE1000, 250h
Multi-lateral lighting (S1)	100	41.7	73.3	3269
Clerestory lighting (S2)	93.3	0	78.5	686
Skylight (top lighting) (S3)	100	30	86.2	2058
Multi-lateral lighting +SD (S1)	100	25	83.3	2347
Clerestory lighting +SD (S5)	15	0	26.1	290
Skylight (top lighting) +SD (S6)	28.3	0	39.9	340
Hybrid typology (case study) (S7)	100	26.7	81.7	2809

displays the analysis of daylighting performance in the women’s prayer hall on the first level, which exhibits complex outcomes across LEEDv4.1, UDI_{300–3000lux}, and average (WPI). Multi-lateral lighting stands out with an sDA_300/50% score of 100% and a UDI_{300–3000lux} of 73.3%, providing non-effective and balanced daylighting with the highest percentage of 41.7% ASE_1000,250h due to the direct penetration of sunlight from the eastern opening. Clerestory lighting up performs with a 78% in UDI_{300–3000lux}, and high sDA_300/50% score of 93.3%, and elimination of sun exposer with zero percent showing an optimum daylight quality while recording a perfect average illuminance of 686 lux. Skylight strategies, although commendable in sDA_300/50% and UDI_{300–3000lux} metrics, exhibit a lower ASE_1000,250h value of 30% which is less than the men’s prayer hall due to the use of internal glazing that is used for separation purposes. The incorporation of shade devices (SD) results in a reduced UDI_{300–3000lux} below the recommended value, implicating a loss of daylight quality in particular for clerestory and skylight typologies. Nevertheless, a hybrid typology that amalgamates all lighting types and SD does not achieve a balanced LEEDv4 score and UDI_{300–3000lux}, with a high WPI of 2809 lux, which indicates this inconsistency of combining these typologies to achieve the visual comfort. This intricate web of results underscores the challenge of realizing an integrated, climate-sensitive, and user-focused daylighting strategy for prayer halls in mosques.

3.2. Hourly Daylighting Quantity

3.2.1. Men’s Prayer Hall Analysis

In our investigation of various daylighting scenarios within mosque spaces, several patterns emerge as presented in Figure 8. Starting with the multi-lateral lighting (Scenario 1), this design capitalizes on multiple vertical openings positioned strategically on three sides. The predominant focus on the south–north axis and the eastern facade ensures ample daylight penetration. At 2 m during summer at 12.30 PM, the illuminance reaches a staggering 20,101 lux. However, as one ventures further from these fenestrations, there is an evident decline in brightness, underscoring the dominant influence of these direct openings. Yet, the Ui value of 0.45 suggests challenges in maintaining uniformity, especially in areas distant from these fenestrations. Scenario 4 introduces a twist to the multi-lateral lighting by integrating vertical shading devices. These shading structures aim to temper the direct sunlight, mitigating potential glare. While the illuminance at 2 m is slightly moderated compared to Scenario 1, it still remains significantly high. The vertical shades, although effective in reducing direct glare, do little to enhance the uniformity, as indicated by a Ui of 0.44.

Transitioning to the clerestory design (Scenario 2), this strategy leverages elevated windows, often positioned higher than eye level. Such a design inherently diffuses sunlight, ensuring that even areas distant from the windows receive a fair share of daylight. The implementation of horizontal shading in Scenario 5 further refines this design. At 2 m, during Summer at 12.30 PM, the illuminance stands at 1031.6 lux, an acceptable level that neither overwhelms nor underwhelms. The Ui value of 0.65 is commendable, suggesting a relatively uniform light distribution across the space. Skylights (Scenario 3) introduce a different dimension to daylighting. Harnessing zenithal light, they bathe the interior in a soft glow, especially effective in spaces with high ceilings like mosques. However, skylights can sometimes lead to non-uniform light distribution, with the central areas receiving disproportionate brightness, as also observed by Fakhr, B. V et al. in their study “Design Optimization of the Skylight for Daylighting and Energy Performance Using NSGA-II”, where they found similar challenges in achieving uniform lighting across the space due to skylight configurations [58]. The introduction of vertical shading in Scenario 6 seeks to mitigate this, achieving a Ui of 0.77, a marked improvement. The hybrid approach (Scenario 7) is a bold endeavor, amalgamating various daylighting strategies in a bid to harness their collective strengths. At 2 m, the illuminance peaks at 21,402.8 lux. However, integrating multiple strategies is not without its challenges. The Ui value of 0.47 suggests pockets of uneven brightness, a testament to the complexity of harmonizing diverse daylighting techniques.

In summation, each scenario, with its unique design approach, offers insights into the nuanced balance between brightness and uniformity. The data underscores the importance of tailored design decisions, ensuring that sacred spaces like mosques are not only aesthetically pleasing but also functional and comfortable for their users.

3.2.2. Women’s Prayer Hall Analysis

Located on the mosque’s first floor, the women’s prayer area features a distinctive daylighting profile, significantly influenced by its architectural design. In the multi-lateral lighting scenario, the effect of the eastern exposure is evident. Illuminance near the external glazing reaches about 1470 lux during the Dhuhr prayer, creating a brightly lit environment. Moving 2 m from the interior glazing, illuminance moderates to around 790 lux in summer solstice and 563 lux in winter, displaying the diffused impact of zenithal light from the west. The area’s uniformity index, with the highest value of 0.86, suggests a potential for even light distribution. The clerestory design, combining direct and diffused light, creates a nuanced illuminance gradient. Central areas register below 1000 lux, while the edges are brighter. This design maintains consistent light distribution, as indicated by a uniformity index above 0.6, except during winter solstice at Dhuhr, suggesting effective design implementation. Skylights offer a different lighting approach, with central illuminance often exceeding 2000 lux near the interior glazing. Areas near the eastern facade experience lower levels, below 923 lux in the morning. However, the uniformity index in these areas does not meet the minimum requirement, especially during Asr prayer, indicating uneven light distribution, which aligns with Bashir et al. in their findings that the design of a square skylight lets an excessive light into the various levels [59]. Integrating horizontal and vertical shading devices produces a complex range of illuminance, from 200 lux to 1000 lux. Notably, during Asr prayer, the Worst-Case Performance Index (WPI) drops below 200 lux. Nevertheless, this hybrid approach generally enhances uniformity index values, though WPI often exceeds recommended levels, potentially causing visual discomfort as shown in Figure 9. Overall, the women’s prayer space in the mosque achieves varied illuminance levels in different scenarios. The uniformity index is a crucial indicator of the balance between brightness and even light distribution. The interplay of direct and diffused light in spaces like this prayer hall underscores the importance of architectural choices in enhancing user experience and comfort.

3.3. Daylight Glare Probability (DGP) of Prayer Zone

In sacred spaces, the quality of light can profoundly influence the ambiance and, consequently, the spiritual experience. An examination of the DGP values across various daylighting typologies in the mosque, segmented by the ‘men’s prayer space’ and ‘women’s prayer space’ during the solstice summer, provides valuable insights as depicted in

Table 9. The daylight glare probability of different daylighting typologies integrated in the mosque under clear sky in solstice summer at (12.30 p.m., 15.30 p.m.).

		Scenario 1	Scenario 2	Scenario 3	Scenario 4	Scenario 5	Scenario 6	Scenario 7
Solstice Summer (21 June) -MEN-	12.30 P.M
		DGP = 0.30 Means ILL = 1950 lux	DGP = 0.27 Means ILL = 1731 lux	DGP = 0.63 Means ILL = 7679 lux	DGP = 0.25 Means ILL = 1306 lux	DGP = 0.24 Means ILL = 1124 lux	DGP = 0.47 Means ILL = 5287 lux	DGP = 0.58 Means ILL = 7113 lux
	15.30 P.M
		DGP = 0.28 Means ILL = 1773 lux	DGP = 0.38 Means ILL = 1580 lux	DGP = 1 Means ILL = 40,811 lux	DGP = 0.25 Means ILL = 1174 lux	DGP = 0.33 Means ILL = 2600 lux	DGP = 0.26 Means ILL = 1491 lux	DGP = 0.45 Means ILL = 4869 lux
Solstice Summer (21 June) -WOMEN-	12.30 P.M
		DGP = 0.26 Means ILL = 1575 lux	DGP = 0.32 Means ILL = 2347 lux	DGP = 0.33 Means ILL = 2734 lux	DGP = 0.23 Means ILL = 982 lux	DGP = 0.26 Means ILL = 846 lux	DGP = 0.23 Means ILL = 1127 lux	DGP = 0.32 Means ILL = 2546 lux
	15.30 P.M
		DGP = 0.25 Means ILL = 1298 lux	DGP = 0.34 Means ILL = 2485 lux	DGP = 1 Means ILL = 27,701 lux	DGP = 0.23 Means ILL = 789 lux	DGP = 0.29 Means ILL = 1021 lux	DGP = 0.99 Means ILL = 18,699 lux	DGP = 1 Means ILL = 20,224 lux
Legend

. Upon detailed analysis, the hybrid typology (S7) presents intolerable DGP values for the ‘men’s and women’s prayer space’ at Dhuhr and Asr prayer time, suggesting that during Asr, the combination of strategies might not be effectively mitigating the glare, especially with the westerly sun potentially intensifying the illumination. Scenario 1, primarily focused on multi-lateral lighting, shows an imperceptible glare status, likely due to its emphasis on vertical openings that can manage side illumination more effectively. The clerestory design in Scenario 2, given its high-placed openings, might be drawing illumination from the evening sun during Asr prayer time, explaining its perceptible DGP state in the men’s prayer space. However, its performance during the rest time and women’s prayer space are imperceptible, indicating it manages the overhead sun well, due to blocking the direct penetration at midday. The skylight strategy (Scenario 3), particularly interesting for the ‘women’s prayer space’, has values of 0.33 (Dhuhr) and 1.00 (Asr). The skylight, being a top source of light, captures and diffuses the overhead sun during Dhuhr effectively. But, during Asr, the increased DGP (intolerable state) suggests potential issues with the westerly sun penetrating through the interior window connected with the skylight, intensifying the glare.

Scenarios 4, 5, and 6, which amalgamate various strategies, showcase the potential benefits and challenges of hybrid designs, particularly in an east–west oriented space. Notably, Scenario 5, with its blend of clerestory and vertical fins, emerges superior, indicating the fins’ potential role in mitigating direct westerly light during Asr.

The main results underscore the importance of tailored architectural decisions in managing daylight glare. While the reference model, integrating multiple strategies, offers a holistic approach, it does not consistently ensure the best DGP values. This aligns with findings from other studies, which emphasize that merely combining various daylighting typologies does not guarantee reduced glare. Specific strategies, like those in Scenario 6, which blend elements of vertical and high-level openings, have been recognized in various research as being particularly effective. Such findings resonate with studies conducted in different building types, where hybrid designs, especially those combining high and side openings, have been found to offer a balanced light distribution with reduced glare risks. The effectiveness of vertical fins, as evidenced in Scenarios 5 and 6, echoes similar results in other architectural research, highlighting their role in diffusing and redirecting incoming light, thereby minimizing direct glare. Furthermore, the results underscore the complexities of managing daylight in spaces with specific orientations and design features. The east–west orientation of the ‘women’s prayer space’, combined with its unique design having both external and internal windows connected with a top light, offers a dynamic interplay of light sources. This is evident in the varied performance of the scenarios, especially during Asr. Such findings are in line with other architectural studies, which emphasize the challenges and opportunities posed by east–west oriented spaces. The direct sunlight from the west, especially when combined with overhead sources like skylights or clerestories, requires careful design considerations. In essence, while integrating various strategies can be beneficial, achieving a harmonized daylighting performance requires a nuanced balance, a sentiment reiterated in numerous architectural studies.

4. The Impact of EC Switchable Glazing

The data delineated in Figure 10 showcase the annual distribution of WPI across diverse mosque daylighting typologies, namely, multi-lateral, clerestory, skylight, and a concrete case study both with and without the integration of electrochromic (EC) switchable glazing systems, as juxtaposed against a reference clear glazing system. This exposition highlights the efficacy of EC glazing systems, particularly in dynamically modulating its states in response to the varying intensity and angular orientation of sunlight over time. A noteworthy diminution in WPI levels across all observation points is evidenced, with the annual WPI oscillating between a commendable illuminance range of 450 lux to 960 lux. This range not only elucidates the daylight distribution potential of EC glazing but also manifests a conducive daylighting condition within the analyzed spaces. Nonetheless, a critical examination reveals that the uniformity index, a pivotal indicator of illuminance consistency, is suboptimal across all scenarios, falling below the recommended threshold. This shortfall underscores a potential area of enhancement in achieving a more uniform daylight distribution. On the contrary, the utilization of clear glazing systems across all examined scenarios conspicuously surpasses the recommended illuminance values, underscoring a likely over-illumination. The disparity in illuminance levels is particularly pronounced in the clerestory configuration, which registers the lowest WPI at 2224 lux, and the real case study scenario, which exhibits the highest WPI at 7631 lux.

Figure 11 elucidates the yearly distribution of control states in electrochromic (EC) switchable glazing systems across various daylighting scenarios within mosque architectural configurations. Among the scenarios under consideration, the clerestory configuration maintains a consistent transparent state throughout the year. On the other hand, a substantial inclination towards a fully tinted state, amounting to 64%, is observed in the top light scenario, specifically within the skylight typology from 10:30 a.m. to 13:45 p.m. A notable dynamism in glazing state alteration is manifested in the multi-lateral lighting scenario. Here, a nearly balanced distribution is seen with 47% transparency and 41% full tint on the south–north axis, while an overwhelming 69% transparency is maintained in the eastern orientations, attributed to the integrated shading components associated with the mosque architecture. This case study unravels a complex and irregular dynamism in glazing state transitions, especially when multiple daylighting strategies are amalgamated. The outcomes closely mirror the distribution percentages observed in previously discussed scenarios, thus providing a comprehensive understanding of the interactive performance of smart glazing systems in varying daylighting and architectural contexts. The insights derived from the analysis present a fertile ground for further exploratory studies on optimizing smart glazing systems to enhance daylighting efficacy in religious edifices.

Figure 12 elucidates the complex interplay among various daylighting strategies upon the integration of electrochromic (EC) switchable glazing systems within the men’s prayer hall. The evaluation, conducted through the lens of LEED v4.1 and UDI_{300–3000lux} metrics, sheds light on the performance and efficacy of the daylighting strategies under scrutiny.

The findings indicate that the sDA_300/50% metric consistently remains above the 50% threshold across all configurations both before and after the incorporation of EC glazing in varying states, with the exception of the skylight typology (S3). This exception is attributable to the predominant usage of the opaque state within the skylight typology, which ostensibly impinges on the daylight autonomy. Contrarily, the ASE_1000,250h metric is only realized within the clerestory typology (S2), albeit by a margin of less than 1.4%, and is entirely obviated with the integration of EC glazing. Other typologies witnessed a notable reduction in the ASE_1000,250h metric, with the case study (hybrid typology) recording a reduction of up to 8.7%.

The UDI_{300–3000lux} metric unveils a substantial reduction across scenarios with EC glazing integration by 16.2%, 28.7%, and 20.5% for multi-lateral (S1), clerestory (S2), and skylight (S3) daylighting strategies, respectively, yet maintains an average above 50% except for the skylight typology, which registered at 36%. The case study underscores a significant enhancement in terms of the UDI_{300–3000lux} metric, with a minimum improvement of 35%, attributable to the control system of amalgamated daylighting strategies.

Table 10. The daylight glare probability of different daylighting typologies in prayer hall optimized by EC glazing in solstice summer at (12.30 p.m., 15.30 p.m.).

		Case Study	Scenario 1	Scenario 2	Scenario 3
Solstice Summer (21 June) -MEN-	12.30 P.M
		DGP = 0.26 Means ILL = 1590 lux	DGP = 0.19 Means ILL = 597 lux	DGP = 0.27 Means ILL = 1731 lux	DGP = 0.02 Means ILL = 91 lux
	15.30 P.M
		DGP = 0.17 Means ILL = 292 lux	DGP = 0.18 Means ILL = 433 lux	DGP = 0.21 Means ILL = 797 lux	DGP = 0.34 Means ILL = 486 lux

showcases a comparative analysis of DGP metrics for a range of daylighting typologies within a prayer hall, optimized with electrochromic (EC) glazing systems during the summer solstice at the times of Dhuhr and Asr prayers (12:30 p.m. and 3:30 p.m., respectively). The results underscore a marked decrease in glare when EC glazing is deployed, particularly within top-lit environments. By integrating a glare mitigation approach with the dynamic modulation capabilities of EC glazing, the intolerable and disturbing glare levels are mitigated, achieving imperceptible glare at the specified prayer times. This performance enhancement is attributed to the glazing’s ability to modulate its optical properties transitioning from clear to intermediate and fully opaque states thereby optimizing visual comfort for occupants.

5. Conclusions

This research offers a detailed analysis of optimizing daylighting typologies in mosque architecture in the Kingdom of Saudi Arabia, with a specific emphasis on the integration of electrochromic (EC) switchable glazing. Through extensive radiance simulations and analyses, it has been demonstrated that while daylighting strategies such as clerestory lighting offer an excellent daylighting quantity and quality, challenges remain in terms of uniformity. In contrast, multi-lateral lighting provides substantial uniformity but there is difficulty in controlling sunlight penetration. Skylights, although they offer high levels of illuminance, pose significant issues with glare probability, particularly during afternoon prayers.

The introduction of EC switchable glazing has been shown to effectively mitigate these issues, maintaining WPI within acceptable ranges and significantly reducing DGP, thereby optimizing visual comfort. However, this comes with the caveat of reduced uniformity in daylight distribution, indicating an area for future improvement. The findings reveal that no single strategy fulfills all the performance benchmarks, underscoring the complexity of achieving optimal daylighting in such environments. It is evident that a one-size-fits-all approach is insufficient, and tailored solutions considering the specific spatial dynamics and user requirements of each prayer space are crucial. Based on the insights gleaned from the study, it is recommended that future mosque designs in Saudi Arabia and similar sun path and climatic regions consider the following:

• Integration of EC glazing should be pursued, as it provides dynamic control over daylight penetration, adapting to the changing position of the sun and thus enhancing occupant comfort.
• Clerestory lighting (S2), coupled with shade devices, should be optimized for women’s prayer halls to enhance daylight quality while minimizing sun exposure.
• For men’s prayer halls, the clerestory lighting typology almost achieves the annual and hourly daylighting quantity and quality metrics, without intervention of active strategies such as a smart glazing system, with attention to ensuring uniformity in the central prayer area.
• A hybrid approach (S7) combining different daylighting typologies may be advantageous but requires careful control strategies by integrating EC glazing to avoid high levels of illumination and to maintain sufficient UDI_{300–3000lux}, which indicates this inconsistency of combining these typologies to achieve the visual comfort.
• Daylighting design strategies must account for the intricacies of each prayer zone, with particular attention to balancing illuminance levels, minimizing glare, and achieving uniformity in light distribution.

Future research should investigate the integration of EC glazing with other passive design strategies, such as light shelves, to improve lighting uniformity and overall effectiveness. Additionally, studies should focus on the economic feasibility and long-term durability of EC glazing across various climatic conditions. Another valuable area of inquiry would be the impact of EC glazing on indoor thermal comfort, as well as its influence on architectural aesthetics and user perceptions within mosque interiors. Furthermore, a thorough examination of the energy performance of EC glazing, especially when combined with renewable energy systems, is essential to maximize energy efficiency and substantially reduce energy consumption in mosque buildings.

Finally, as each mosque has its own set of requirements and contextual challenges, a bespoke approach to daylighting design should be adopted, guided by the principles established through this research. This study advances the discourse on sustainable architectural design in sacred spaces, contributing valuable insights that will aid in the evolution of daylighting strategies in mosque architecture. The implementation of these recommendations promises to enhance not only the environmental performance of these spaces but also the spiritual and cultural experiences they provide.