Optimizing BIPV Windows in Dust-Prone Regions: Enhanced Strategies for Energy Efficiency in Semi-Arid Climates

Optimizing BIPV Windows in Dust-Prone Regions: Enhanced Strategies for Energy Efficiency in Semi-Arid Climates | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Optimizing BIPV Windows in Dust-Prone Regions: Enhanced Strategies for Energy Efficiency in Semi-Arid Climates Isra Shorsh¹, Salahaddin Yasin Baper¹ This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8807699/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract The problem of dust continues to be a constant performance barrier to building integrated photovoltaic (BIPV) windows. This paper has innovated the field since the secondary-layer concept is proposed to consist of dust-reduction films, thermo-resistant materials, and optical redirection elements that work together as a multifunctional enhancement system. where most recent research assesses protective layers and optical concentrators as separate strategies. Through a full-scale application of the Smart Health Tower in Sulaymaniyah, a workflow created in Rhino, Grasshopper, Ladybug and PV-syst was executed to recalibrate the performance metrics of existing monocrystalline BIPV glazing. The baseline model established an annual energy yield of 321,685 kWh, applied only in upper part of the windows, serving as the benchmark and validation for evaluating the proposed scenarios. The analysis demonstrates that consolidating UV stabilization, thermal regulation, and micro-optical concentration within a protective layer significantly mitigates environmental degradation while enhancing energy production, loss prevention due to soiling, and long-term facade stability. This paper presents a novel strategy for next-generation BIPV window in dusty and high-irradiance environments by demonstrating the synergy gains achieved on merging protective and optical capabilities. Physical sciences/Energy science and technology Physical sciences/Engineering Physical sciences/Materials science Building-integrated photovoltaics (BIPV) Dust mitigation optical concentrators Multifunctional facade systems Semi-arid climates Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction Building-Integrated Photovoltaics (BIPV) have become a priority in sustainable building designs due to their ability to replace conventional façade materials with energy-generating systems, particularly in the form of photovoltaic windows that integrate electricity generation, daylighting, and solar control into one architectural element, Building-Integrated Photovoltaics (BIPV) have become a priority of the sustainable building design. As urbanization increases and buildings grow taller, façade surfaces provide significantly more area for solar harvesting compared to rooftops, making them essential for achieving onsite renewable energy targets in dense cities [ 1 ]. This is especially relevant in semi-arid climates, with extremely high solar irradiation, where buildings face equally high cooling loads, which calls the need of technologies in facades with the ability to minimize heat gain whilst generating renewable energy [ 2 ]. In these areas BIPV windows have a twofold environmental benefit, reducing the energy use of the HVAC system and utilizing abundant sunlight in large amounts, yet the actual performance of the system is limited by the environmental elements that are not yet addressed in literature or practice. Dust accumulation is one of the most severe issues that restrict the performance of BIPV windows in semi-arid and dusty climate conditions. The deposition of dust on photovoltaic glazing causes significant optical losses, because the particulates suspended in the air are scattered, absorbed and block solar energy entering the photovoltaic cells, thereby reducing the number of photons reaching the photovoltaic cells [ 3 ]. As previously indicated by experimental studies, nonlinear reductions of short-circuit current (Isc), maximum power (Pmax) and total efficiency are observed in all cases even by very low levels of dust density both through optical shading and thermally induced degradation [ 3 ]. Gholami et al. demonstrated that up to 25 percent of transmission coefficients could be lowered by dust deposition on tilted glazing with sensitivity being heavily dependent on the tilt, orientation and local wind direction patterns [ 4 ]. Effects are even worse in desert adjacent areas, with Sadat et al. reporting efficiency loss of up to 98 percent in desert areas of Iran during heavy deposition, indicating the high sensitivity of PV glazing to semi-arid climate [ 5 ]. These losses are ever worse by the fact that vertical facades do not get natural cleaning by rainfall as much as roof-mounted systems, resulting in acceleration and the continued accumulation of dust all year round [ 6 ]. The problem is further aggravated by the interactions of dust, heat and optical performance. Dust accumulation increases operating temperature of modules (by capturing solar energy) and blocking uniform heat dissipation (by blocking uniform cooling of heat) and therefore reduces efficiency of temperature-dependent thin-film and semi-transparent BIPV systems [ 7 ]. According to Shi and Zhu, one of the essential drawbacks of BIPV windows is thermal loading because higher operating temperatures contribute to greater thermal conductivity to the interiors, higher U-value, and lower electrical output at the same time [ 7 ]. These two penalties make semi-arid climates to be highly challenging to BIPV glazing where dust depositions and extreme ambient temperatures co-exist. The optical and electrical performance has greatly enhanced with technological advances in the design of BIPV windows but none of them deals directly with dust accumulation. Theoretically, transparent windows with photovoltaic characteristics can be created using transparent electrodes, e.g., AgNW/AZO multilayers, and were demonstrated to be able to daylight, de-ice, and harvest solar energy [ 8 ]. Moor et al. have produced Luminescent solar concentrator (LSC) windows that have high visible transmittance and power outputs to 50.5 Wp and have proven to be viable in facade integration [ 9 ]. Likewise, Vasiliev et al. introduced spectrally selective energy-harvesting windows that are highly transparent with the utilization of CIS PV modules and luminescent materials to maximize the performance of the windows under the diffuse light [ 10 ]. The potential of concentrator-based BIPV windows is also significant; Xuan et al. have shown that lens-walled CPC windows can be expected to exceed daylight uniformity, reduce glare and provide more than six times more active areas of illumination compared to conventional semi-transparent PV glazing [ 11 ]. These new advancements show an outstanding development of integrating aesthetics, energy production and visual comfort in BIPV windows. Nevertheless, current BIPV window technology nearly lacks dust mitigation strategies even though dust has been identified as one of the most critical and recurring challenges in PV operation by several reviews. According to Kazem et al., dust was able to decrease the PV efficiency by up to 80 percent based on the climate and dust properties, a fact that highlights the urgency of incorporating dust-resistant designs instead of just using external cleaning interventions [ 12 ]. Gupta was also able to find dust as an unavoidable environmental stress factor in many climates and emphasized the fact that the intensity of losses caused by dust is dependent upon the particle morphology, moisture content, the angle of inclination and exposure duration [ 13 ]. Cleaning technologies Can be either manual washing, mechanical brushes, or electrodynamic screens, which are usually not feasible to high-rise BIPV facades either due to cost, accessibility, safety considerations, or lack of compatibility with architectural requirements [ 14 ]. Hydrophobic nanocoating: (self-cleaning layer of SiO2) as tested by Alamri et al. can enhance power output by up to 15 percent over dusty panels, but durability, optical clarity and long-term environmental performance are an issue in large facade applications [ 6 ]. Overall, even though there are current solutions that would partially alleviate the problem of dust, none of them offer a long-term and integrated, facade-compatible solution to the problem that would be applicable in semi-arid regions. Facade and glazing Parallel studies of facade and glazing performance have indicated that the energy efficiency of multi-layered facade systems or optical improvements can be considerably enhanced with appropriate integration. Attoye et al. have discovered that the electrical performance of BIPV facade layers (such as glass geometry, coverings, and distance between PV cells) can be optimized through customization to increase electrical performance by up to 80 percent, indicating the significant value of compositional facade modification [ 15 ]. Similarly, the optimization of the facade design in the hot climate underlines the need to combine the shading and glazing technologies with the PV systems to decrease the cooling load and improve the overall performance of the building [ 2 ]. These results are a strong affirmation towards the idea of introducing a secondary or protective (optical) layer in front of BIPV windows as an element of facade customization and not an external cleaning device. Moreover, the research on solar concentrators and optical enhancement systems is strong evidence that additional optical layers can improve PV power output in the case of diffuse or scattered light- exactly the optical conditions created by dust. According to Rashid, the analysis of Fresnel lens systems enhances the concentration of the sun and thermal collection in the different atmospheric conditions, indicating that they perform well even in the partially obscured irradiance [ 16 ]. The CPC windows used by Xuan et al. also improve light capture with oblique angles, while Vasiliev et al. showed that LSC windows are stable to non-ideal lighting conditions due to their ability to work with an orientation or tilt angle [ 10 ]. Since dust elevates the diffuse fraction of solar radiation, the concepts of the concentrators are directly relevant in reducing the optical losses associated with dust in BIPV windows. Despite evident synergies, there is no literature that combines a secondary optical layer/protector or concentrator as a dust-reduction measure on BIPV windows in semi-arid environments. This can be considered a critical research gap at the intersection of façade engineering, photovoltaic performance, and environmental resilience. It is important to address this gap to achieve the maximum potential of BIPV windows in areas where dust, heat, and high solar exposure coexist. Consequently, this study will design the BIPV windows appropriate to dust-prone semi-arid regions by assessing the efficiency of a secondary-layer/protector or concentrator that is installed in front of the photovoltaic glazing. The suggested system will aim at (1) lowering dust deposition on the glass surface, (2) increasing optical capture at diffuse irradiance, and (3) preserving high transmittance of visible light and thermal comfort. This research merges conclusions of dust behavior, concentrator optics, and BIPV window technologies to propose a novel façade-integrated solution that innovates energy efficiency in unfavorable environmental conditions. 2. Literature Reviews 2.1 Introduction to Building-Integrated Photovoltaics (BIPV) and Facade Implementation. Building-Integrated Photovoltaics (BIPV) represent a type of photovoltaic system in which traditional building envelopes are replaced and simultaneously generate electricity, which is a multifunctional solution to enhancing building energy performance [ 1 ]. In contrast to the building-Applied Photovoltaics (BAPV), which are mounted on existing surfaces, BIPV systems are used as structural elements in the form of glazing, cladding, louvers, and shading equipment, in addition to both structural and environmental functions [ 17 ]. The increased demand for energy-efficient and sustaining buildings has increased the implementation of BIPV solutions especially in high-solar-available areas, where it provides a direct pathway to reduce grid dependance and carbon footprint in operation [ 2 ]. Facade-based BIPV is one of the envelope-integrated applications that have received the greatest attention because it has the potential to turn the large amounts of vertical surfaces of buildings into useful energy-producing systems [ 18 ]. This is more applicable in urban settings and high-rise typologies, whereby rooftop space is minimal and cannot support huge energy demands. Photovoltaics that are integrated on the facade can also be predictably incorporated into the architecture which provides the designers with opportunities to modulate transparency, aesthetics, orientation and customization of modules to suit the building’s needs [ 15 ]. Recent developments have developed semi-transparent photovoltaic glazing, colorful modules, and controllable facade geometries, which show an even greater improvement of the architectural viability and visual acceptability of BIPV [ 1 ]. Facade-integrated BIPV is more important in hot and semi-arid areas, where it can compensate for massive cooling loads beside harvesting massive solar energy throughout the year [ 2 ]. Nevertheless, the operation of facade-mounted PV, in particular, vertical glazing systems, is highly sensitive to environmental factors including dust layers, irradiance fluctuations and thermal loads that require further research and optimization techniques discussed in later sections below. 2.2 Semi-Transparent and Transparent BIPV Window Technologies Semi-transparent and transparent BIPV windows are the advanced type of photovoltaic glazing systems designed to make use of daylight, control solar gains, and produce on-site electricity by means of selective spectral absorption [ 25 ]. Semi-transparent designs are normally based on controlled cell spacing, patterned deposition or partial absorber coverage, allowing a calibrated balance between visible-light transmittance and electrical performance while maintaining architectural appearance [ 20 ]. Their efficiency is controlled by spectral selectivity, where ultraviolet and near infrared wavelengths are transformed into electricity as the visible spectrum goes through the glazing and daylight can be used without serious luminance obstruction [ 21 ]. Transparent BIPV technologies go beyond this principle with the luminescent solar concentrator (LSCs) which absorbs non-visible light and then re-emits photons towards edge-mounted PV cells and sustains optical clarity with dispersed electrical generation [ 9 ]. Other strategies use spectrally selective coating, which transfers the visible light but directs the UV/NIR to internal layers of active photovoltaic material, enabling complete transparency without lowering the energy harvesting potential [ 10 ]. Recent advances in transparent conductive electrode such as AgNW- and nanoparticle-based films, further increase optical-electrical efficiency since they enable the flow of charges without causing visual artifacts [ 8 ]. All these technologies together create a varied design landscape where the transparency, power density, and thermal performance should be balanced based on the climatic and facade-related environment. 2.3 Climatic Stressors and Dust Deposition Dynamics in Semi-Arid Regions Semi-arid areas have a specific set of environmental stress factors, which increase the operational difficulties of photovoltaic glazing systems. These types of climates have consistently high solar irradiance, low moisture content of the atmosphere and low levels of annual precipitation making ordinary deposits of particulates to stay on the surfaces of facades over a long period without natural cleaning periods [ 2 ]. The clear-sky predominance conditions also create a radiation field that dominates the intense beam components, while varying wind velocities and turbulence patterns redistribute the aerial particulates in the building envelope in extremely localized deposition regimes [ 4 ]. Vertical Façade-integrated PV windows are especially exposed to these dynamics when façade-mounted systems behave differently to atmospheric flow fields than those roof-mounted PV; wind-induced sediment, facade scale vortices and Building-related pressure variations interact to affect deposition rates and spatial uniformity [ 22 ]. Both macro and micro mechanisms control dust depositions in these areas. At the macro scale, mineral aerosols as the result of soil erosion, construction debris, vehicular upheavals, and long-range transported dust clouds are the sources of particulates, which produce a range of particles in the form of fine silicates and aggregate mineral particulates that have high optical and adhesive characteristics [ 4 ]. On a micro level, adhesion of the particles is dictated by electrostatic interactions, capillary bridges created during low humidity and surface-energy differences between dust minerals and glazing materials, which favor long-term fouling on photovoltaic surfaces [ 24 ]. When deposited, small particulates infiltrate micro-textures or irregularities in coating and cannot be removed by natural airflow to form optically dense layers that could change spectral transmission profiles, and angular distributions of incident radiation [ 13 ]. Moreover, the absorptive properties of mineral dust amplify localized surface temperature and exacerbate thermal loading on PV-glazing layers, which exacerbates electrical degradation and heat transfer to the building interior [ 7 ]. These climatic and deposition processes in combination demonstrate why BIPV windows in semi-arid climates should be designed with optimization techniques that help mitigate the effects of particulate adhesion, spectral distortion, and thermally induced loss of performance as well. 2.4. Impact of Dust on PV and BIPV Window Performance The collective effect of dust depositions is the degradation of photovoltaic glazing which disrupts its optical, electrical, and thermal mechanisms, resulting in the loss of system efficiency [ 1 ]. Transmittance is reduced by particulate layers, which absorb and scatter incident radiation, as well as disrupting spectral distributions needed to achieve effective energy harvesting in semi-transparent and transparent PV windows [ 7 ]. These optical losses are directly converted to electrical losses and result in disproportional losses in short circuits and maximum power output even in the presence of moderate soiling [ 12 ]. Also, mineral dust leads to surface absorption and increases PV-glazing temperature, elevates resistive losses and challenging operational stability in the high-irradiance settings characteristic of semi-arid climates [ 7 ]. These combined impacts underscore the need to adopt specific mitigation strategies regarding BIPV facades. 2.5 Dust Mitigation Strategies and Their Practical Limitations There is a variety of dust-reduction strategies studied to be applied to photovoltaic systems, with most of them being operationally or technically inapplicable to BIPV windows integrated into the facade. Optical clarity can be temporarily restored by conventional methods such as manual or water-based cleaning, which is expensive, labor-intensive, time-consuming and unfeasible to use in high-rise facades of semi-arid areas where rapid re-accumulation is evident, and water scarcity is a severe constraint [ 12 ]. Likewise, automated and robot cleaning machines need mechanical rails or external support that do not fit within the structural and aesthetic limits of transparent glazing systems, limiting their application to BIPV installations [ 13 ]. Surface-Mitigation approaches are most widely investigated. Hydrophobic nano-coatings prevent adhesion of particulate matter by changing the surface free energy thereby allowing partial self-cleaning during dew cycles or light rains and unlike; however, their long-term effectiveness is undermined by UV degradation and abrasion by mineral dust, requiring periodic reapplication [ 6 ]. Indirect mitigation such as anti-UV and anti-scratch layers, which maintain surface smoothness and optical stability because micro-abrasions and UV-related polymer degradation is known to raise dust anchoring sites and accelerate fouling of PV glazing [ 13 ]. However, these layers alone are not capable of significantly lowering particulate depositions and their protective effects weaken extended environmental exposure. Maintenance operational (O&M) strategies also represent another mitigation avenue and research results indicate that optimized zone-specific cleaning intervals can mitigate performance losses better than standardized schedules [ 14 ]. Nonetheless, the mitigation of O&M is limited by access, safety, and cost of facades at the building scale. Although these methods are partial, they are not a long term, passive, or facades friendly solution. This gap has prompted the investigation of new secondary layers- such as concentrator films, micro-CPC sheets and thermal-resistant materials that combine dust shielding with optical or thermal development benefits functions, showing a more holistic approach to optimize BIPV windows in semi-arid climates [ 16 ]. 2.6 Thermal-Responsive Glazing Materials Relevant to BIPV Optimization Thermally adaptive glazing materials such as nanoparticle-enhanced coatings, thermotropic polymers, and Phase-change layers, provide passive mechanisms of solar heat gain, stabilizing surface temperatures in high-irradiance conditions [ 19 ]. These materials change the transmittance or scattering at different temperatures or spectral activations and thus reduce overheating in PV-integrated glazing and eliminate efficiency loss due to thermal effects [ 23 ]. Their ability to lower thermal load without blocking visible light transmission gives them a conceptual basis to be used in thermal-resistant protective layers in optimizing BIPV strategies in climates where dust load increases surface heating [ 7 ]. 2.7 Optical Concentrator Technologies Applicable to BIPV Windows Technologies of optical concentrators provide a viable way of improving the performance of facade-based photovoltaics by controlling the angular and spectral distribution of incident solar radiation. Compound parabolic concentrators (CPCs), along with their variations-CCPC and RACPC geometries, are non-imaging systems that are developed to redirect oblique and diffuse irradiance to photovoltaic surfaces to enhance the light capture in circumstances where the direct irradiance is reduced or is irregularly distributed [ 11 ]. The fact that they have an acceptance-angle flexibility makes them especially applicable in semi-arid conditions, where dust-filled atmospheres enhance the diffuse component of the solar radiation and diminish the strength of the direct beam irradiance [ 16 ]. Another type of optical enhancers is luminescent solar concentrators (LSCs) which are non-visible wavelengths via embedded fluorophores and re-emit photons at the edge-mounted photovoltaic components to allow transparent or semi-transparent glazing designs with distributed electrical productions [ 9 ]. LSC or hybrid concentrator systems use spectrally selective coatings to further refine the flow of optical routing by filtering visible while directing UV-NIR content to PV absorbers without compromising architectural transparency energy yield [ 10 ]. Fresnel and Holographic type of concentrators make these principles more applicable in terms of wavelength-specific light steering and compact optical concentration, making possible integration as secondary protective layers on façade glazing [ 24 ]. In general, these elements provide a conceptual framework for protective layers that serve two functions at once: protecting BIPV glazing from dust deposition and providing an improvement in irradiance capture. Table 1 Classification of Optical Concentrator Technologies for BIPV Windows Concentrator Type Operating Principle Key Functional Role in BIPV Windows Typical Materials Compound Parabolic Concentrator (CPC) Wide-angle non-imaging collection and redirection of incident light. Boosts irradiance capture and energy yield with minimal impact on outward visibility. Aluminum-coated or silver-coated reflective surfaces; UV-stable polycarbonate or acrylic housings. Luminescent Solar Concentrator (LSC) Absorbs non-visible wavelengths and guides re-emitted light to edge PV cells. Enhances spectral utilization and improves daylight uniformity while maintaining transparency. PMMA or polycarbonate matrices doped with organic dyes, quantum dots, or rare-earth phosphors. Micro-Optic Arrays (Lenses/Prisms) Micro-structured refraction or diffraction to steer sunlight. Supports improved indoor visual comfort and more uniform façade illumination. Molded PMMA, polycarbonate, glass micro-lens sheets, or nano-imprinted optical polymers. 2.8 Façade Design, Customization, and Multi-Layer Optical Systems The photovoltaic systems that are integrated into facade operate in very limited architectural and environmental settings and therefore geometric customization and multi-layer configurations are necessary to optimize their performance. Customization approaches, such as the ability to adjust cell spacing, glass layering, thickness of the substrate, and facade geometry allow designers to customize optical transmission as well as photovoltaic productivity to the specific building orientations and the urban environment [ 15 ]. These geometric and compositional adjustments make BIPV facades balance architectural requirements with electrical functionality by regulating shading effects, daylight penetration, and the ability to selectively regulate solar gains [ 25 ]. This is further enhanced by multi-layer facade systems such as double-skin systems and composite glazing stacks which comprise functional interlayers that alter spectral transmission, thermal behavior or surface interactions but do not affect structural integrity [ 2 ]. These layered arrangements facilitate differentiated optical pathways and thermal buffering impact and provide prospects of incorporating other protective or optical features at the facade boundary. In this context, the idea of a secondary layer (i.e., protective film, micro-optic sheet, and concentrator element) fits well into current facade engineering practice and offers viable design options to reducing dust deposition, to redistribute incident radiation, and to increasing the stability of performance of BIPV windows in semi-arid climates. 2.9 Research Gap and Rationale Existing studies on BIPV windows have little insight into their performance in semi-arid and dust prone climates where the accumulation of dust has a strong influence on optical transmission and thermal loading [ 7 ]. Current dust-reduction measures, including hydrophobic coating, anti-UV coating and standard cleanings, have inconsistent longevity and do not apply well to transparent facade applications [ 12 ]. Even though Optical concentrators and protective layers have not been assessed together, their mutual potential to increase irradiance capture and reduce glazing exposure to dust has not been systematically analyzed in BIPV window systems [ 16 ]. Additionally, none of the previous studies applies an integrated workflow involving facade discretization, irradiance modeling, dust-loss characterization, and multi-scenario PV simulation. These gaps are the reason to consider comprehensive secondary-layer strategies to improve flexibility and energy performance of BIPV windows in semi-arid dust climates. 3. Methodology 3.1 Overview of the Methodological Framework The research uses a multi-stage methodological approach that aims to assess the functionality of a complete BIPV window system in a semi-arid environment and determine the effect of different dust-reduction measures. The methodology incorporates four fundamental components, which include geometric reconstruction of the case-study facade, climate-based solar irradiance modelling, characterization of dust-losses, and assessment of photovoltaic energy-yields. The entire facade of Smart Health Tower is 5,814 m² and it is discretized into orientation-dependent segments to capture different solar exposure of the building envelope. The incident irradiance on each segment of the facade is simulated using the hourly climatic conditions featuring sun geometry, sky conditions, and vertical-surface behavior. These irradiance values are then applied based on the dust related attenuation factors and temperature-dependent performance to represent the semi-arid soiling conditions. The irradiance and loss parameters after the processing are then used to estimate annual photovoltaic output to make a consistent comparison of the baseline configuration with the six mitigation scenarios. This combined framework certifies that geometric, climatic, optical, and electrical characteristics of facades-integrated photovoltaics are assessed in a coherent manner, providing an analytical basis of investigating scenario-based studies in subsequent sections. 3.2 Case Study Building and Façade Geometry The Smart Health Tower in Sulaymaniyah has been used as case study to perform this research because it is a fully glazed, high-rise healthcare building located in the semi-arid area with high solar radiation, high concentration of airborne particulate matter, and low rainfall. The building includes an actual, operational BIPV system that includes 900 semi-transparent monocrystalline panels mounted on the two curved faces of the building, 450 on each side. This system offers a total DC capacity of 232 kWp, which is linked to two 110 kW Huawei SUN2000-110KTL-M0 inverters (220 kW AC) and forms a grid-tied PV subsystem that partially offsets the high energy consumption of the hospital. According to the Facility records of the hospital, power consumption is highest in July, which is about 759,000 kWh; this highlights the fact that year-round medical activities in a hot and semi-arid climate are energy intensive. To conduct the study, the actual applied BIPV in the upper part of the windows as bands or belts consists of 753 m² of glazing, is used as a validated physical reference for glazing type, module transparency, and facade-integration approach. Nevertheless, to assess the performance possibility of transparent BIPV windows on the building scale, the entire facade of the Smart Health Tower is re-created in Rhino and simulated as a complete-BIPV envelope. A precise 3D model of the tower was created with the use of architectural documentations, on-site verified photographs, and geometrical surveying, which led to a total simulated facade area of 5,814 m². The facade was subdivided into segments of orientation-dependent surfaces to reflect the fluctuation of the incident solar radiation in the curved geometry of the building. A climate-aligned solar path model for Sulaymaniyah was overlaid onto the reconstructed façade to visualize seasonal solar trajectories and calculate their interaction with the building’s unique curvature. These climatic and geometric foundations illustrate the dust attenuation modeling, irradiance mapping, and photovoltaic performance simulations explained in the following sections. Therefore, the extended full-façade BIPV configuration is a hypothetical design scenario which is developed to investigate maximum feasible energy generation possible under semi-arid environmental conditions. 3.3 BIPV Window Model and Layer Configuration 3.3.1 Baseline Photovoltaic Glazing Structure The baseline facade model replicates the semi-transparent monocrystalline BIPV glazing typology which is mounted in the current photovoltaic belt in the Smart Health Tower. The actual system comprises 980 semi-transparent monocrystalline modules applied over the two curved sides of the tower (490 modules in each side) giving it a total system DC capacity of 232 kWp on a glazed 753m² area. This system has two Huawei SUN2000-110KTL-M0 inverters (total 220 kW AC capacity), linked to a grid-tied subsystem that partially meets the electrical needs of the hospital, The applied glazing system includes an exterior glass pane, encapsulating materials, crystalline silicon cell layer, rear encapsulant, and interior structural glass, which does not have a secondary optical or protective layer. This real-world configuration is used as a reference BIPV window system to all the baseline simulations in this research. 3.3.2 Semi-Transparent Monocrystalline PV Technologies The modeled BIPV system is characterized by transparency, which is achieved by a spacing-based semi-transparent crystalline silicon configuration with the monocrystalline cells spread out with controlled inter-cell gaps to allow transmission of daylight through. This method parallel with the present BIPV production practice of transparent crystalline modules. The technology applied in the actual installation, which is the high-performance option. The efficiency of the model is Monocrystalline (34% efficiency) This technology concept is an expression of realistic BIPV decision-making, in which energy yields are important in determining the system. 3.3.3 Module Dimensions and Full-Façade Assignment The actual BIPV belt module is (0.81 × 1.01) m whereas the simulated full facade envelope BIPV module being (3.0 × 1.0) m and (2.0 × 1.5) m to enable full geometrical cover of the recreated 5,814 m² facade. These module formats are mapped in all the surface areas to maintain constant irradiance analysis and performance analysis. 3.3.4 Optical, Thermal, and Electrical Material Properties The assigned material properties such as solar transmittance, visible light transmission, absorptance, thermal conductance and temperature coefficients are done based on manufacturer data and published data of semi-transparent crystalline BIPV systems. Electrical simulations are based on the nature of the current tower subsystems along with a representative DC-AC ratio of 1.05 and the inverter efficiency in line with the Huawei SUN2000-110KTL-M0 units on-site. All the baseline properties are fixed during simulations to facilitate a reasonable comparison between mitigation scenarios. 3.3.5 Role of the Secondary Layer in Subsequent Scenarios In the baseline configuration no secondary layer is used. The outer secondary layer representing concentrators, protective films, optical coatings and operational mitigation measures are only presented in the scenario analysis of Section 3.6 . This keeps the main glazing structures integrity and enables the specific assessment of the dust mitigation measures. 3.4 Simulation Tools and Computational Environment To implement the methodological framework, a combination of tools that have been utilized are Geometric modeling, environmental simulation, and photovoltaic performance benchmarking. All the simulations are carried out in a coordinated digital workflow involving Rhino 3D, Grasshopper, Ladybug Tools, and PVsyst, with each software providing a specific analysis function aligned with facade-integrated photovoltaic evaluation. Rhino 3D is the main geometric workspace on which the complete three-dimensional model of the Smart Health Tower is built, its geometry of curved facades, layout of the fenestration and discretized BIPV surfaces. This is a geometric platform that is directly connected to Grasshopper, providing a parametric interface to automate facade segmentation, photovoltaic module assignment, and control material and performance parameters throughout the building envelope. Ladybug Tools are used in the Grasshopper environment to process the local EPW climate file of Sulaymaniyah. By applying radiation analysis components and solar-position algorithms, the program also calculates hourly incident irradiance values per segment of the facade, creating the values explicitly considering the site-specific geometric of the sun, and sky conditions. These are the facade-resolved irradiance outputs which are the main climatic and geometric basis of further performance evaluation and are further modified in Grasshopper to consider dust related attenuation, and temperature dependent effects. PVsyst is featured as an electrical benchmarking and validation instrument, and not the main irradiance modeling engine. The software is utilized to check the baseline electrical yield, performance ratio, and loss structure of BIPV configuration in the facade are in line with industry-standard PV performance modeling. To ensure the baseline system behavior is electrically realistic and comparable to conventional PV performance assessments, the irradiance-informed PV parameters derived from the façade-level analysis are linked with PVsyst loss definitions. It is a coherent integrated computational environment that guarantees consistency among geometric representation, climate-based irradiance modeling, and electrical performance benchmarking which forms a strong and clear foundation for measuring the baseline BIPV system and the secondary-layer mitigation scenarios explored in the following sections are. 3.5 Secondary Layer Concept and Novelty of the Study This paper proposes an externally mounted glass secondary layer as a facade scale installation to enhance energy production and to improve optical, thermal, and dust-resistance capabilities of transparent BIPV windows in semi-arid climate. Although the current facade of the Smart Health Tower already features a primary semi-transparent BIPV belt without any type of protective or optical enhancement, the approach extends this concept by incorporating a simulated secondary glazing layer to the entire 5,814 m2 building envelope to evaluate the functional possibilities of the building in general. The secondary layer is represented as a free-standing glass sheet arranged outwardly and separated by a ventilated air gap between the BIPV glazing and the secondary glass pane. This design is an effective triple-layer facade system, which has several known architectural and thermal advantages, such as: (1) minimized the conductive and convective heat transfer across the buffering air cavity; (2) moderated surface temperatures on the PV layer, thus, reducing the thermal-induced electrical losses; (3) changed airflow patterns which decrease the adhesion and deposition of airborne dust; (4) mechanical and UV enveloping that shields the PV glazing against abrasion and long-term degradation; and (5) enhanced optical management by selectively modifying the outermost layer while keeping the PV assembly unchanged. Every dust-reduction measure is done by changing the external layer, such as adding hydrophobic treatment, concentrator film geometry, UV-resistant coating or thermally resilient materials, while keeping the underlying system of BIPV the same. This isolated-variable method guarantees direct comparing between all the six scenarios. The novelty of this study is in transferring the analysis of dust-reduction procedures from isolated module-level interventions to a façade-integrated, triple-layer architectural system. No other research has evaluated full-building BIPV functionality under dusty semi-arid environments with an externally mounted protective glazing layer as a versatile platform of several mitigation measures. This façade-scale perspective offers a more practical and operational way through which BIPV can be implemented in harsh climatic areas. 3.6 Dust Mitigation Scenarios There are six secondary-layer configurations, which were made to test their effectiveness on the optical, thermal, and dust-related performances of the triple-layer BIPV facade system. The core BIPV glazing in any case is not altered, but the outer secondary glass layer, physically separated by an air gap from the core facade, varies to reflect one mitigation strategy at a time. Every scenario is executed by modifying the corresponding optical, thermal or operational parameters in the simulation environment. The scenarios are defined as the following: 3.6.1 Scenario 1: Optical Film Layer An optical film layer is a coating composed of thin light-management coating layer installed on the exterior of BIPV window to redirect the solar radiation to the photovoltaic surface. It enhances the utilization of diffuse and oblique incident light, helping to maintain effective irradiance under dust-attenuated conditions without changing the window geometry or PV area. 3.6.2 Scenario 2: Anti-UV / Anti-Scratch Surface Layer A durable polymer-based UV-resistant and anti-scratch coating is assigned to the secondary glass layer. The scenario decreases micro-abrasion and surface degradation effects by stabilizing long-term transmittance in the optical model. 3.6.3 Scenario 3: Hydrophobic Coating Layer A high–contact-angle hydrophobic treatment is applied to reduce dust adhesion. In the simulation, this is represented by a lower dust-retention coefficient and reduced soiling-loss progression. 3.6.4 Scenario 4: Thermal-Resistant Layer A thermally stable external glazing material is introduced to minimize heat absorption and mitigate dust-induced thermal rise in the PV layer. This is achieved by Implementing modified thermal-loss coefficient of the façade assembly. 3.6.5 Scenario 5: Modular Operations and Maintenance (O&M) Cleaning Strategy This scenario shows improved operations and maintenance (O&M) cleaning, demonstrated by altering the soiling-accumulation curve of the façade. More regular cleaning periods return the transmittance of the external secondary glass layer to baseline levels, minimizing long-term dust buildup. No material changes are introduced; only the cleaning frequency is modified to separate the effect of optimized maintenance on dust-related performance losses. 3.6.6 Scenario 6: Micro Compound Parabolic Concentrator (micro-CPC) Layer A micro compound parabolic concentrator (micro-CPC) layer is incorporated within the secondary glazing to geometrically concentrate and redirect incident solar radiation onto the photovoltaic surface. The micro-structured concentrators improve the effective irradiance on the PV layer by capturing light over a wider range of incidence angles without mechanical tracking or additional PV area. 3.6.7 Comparative Evaluation Approach All the mitigation scenarios are checked against the baseline of BIPV facade using the same geometry, climatic inputs, and electrical parameters. The optical, thermal or dust related properties of the external secondary glass layer are only modified in each case. Such controlled configurations ensure any variation in energy yield or performance arising solely from the mitigation mechanisms of being examined and enabling a direct and consistent comparison between all scenarios. Table 3.1 lists the material configurations, simulation parameters and functional mechanisms in the six dust-mitigation cases applied on external secondary glass layer. Scenario Mitigation Type Material Simulation Implementation Parameters Functional Effect / Mechanism 1. optical Film Layer Optical light management Angle-selective optical film Modified angular transmittance; light-redirection coefficients Redirects diffuse and obliquely incident radiation toward the PV surface, increasing effective irradiance under dust-attenuated conditions 2. Anti-UV / Anti-Scratch Layer Surface durability UV-resistant polymer coating Stabilized transmittance; reduced degradation factor Maintains long-term optical clarity; reduces micro-abrasion impacts 3. Hydrophobic Coating Layer Surface dust control High-contact-angle hydrophobic treatment Lower dust-retention coefficient; reduced soiling-loss rate Minimizes dust adhesion; prolongs clean-surface performance 4. Thermal-Resistant Layer Thermal mitigation Low-absorptance thermal-stable glass Reduced thermal-loss coefficient; lower PV temperature gain Mitigates temperature-induced electrical losses 5. Modular O&M Strategy Operational cleaning Adjusted cleaning interval strategy Modified soiling-accumulation curve; periodic restoration events Reduces long-term dust buildup; restores transmittance more frequently 6. Micro-CPC Layer Geometric concentration Micro compound parabolic concentrator array Concentration ratio; angular acceptance range; irradiance amplification factor Geometrically concentrates incident radiation onto the PV layer, increasing effective irradiance without tracking or additional PV area 3.7 Simulation Setup and Parameterization The baseline and scenario based BIPV facades were assessed on a performance assessment by providing a simulation workflow that incorporated Rhino-Grasshopper, Ladybug Tools and electrical benchmarking with PVsyst. The geometry of the facade, climate data, discretization scheme and electrical layout are all the same across all scenarios to allow a direct comparison of all scenarios. Differences between the scenarios are introduced solely by changing the optical, thermal, or dust-related characteristics of an exterior secondary glazing layer and the primary BIPV system remains unchanged. 3.7.1 Climate and Irradiance Modeling Hourly climatic information of Sulaymaniyah was imported with regional EPW file and the Ladybug Tools processed in the Grasshopper environment. The Perez sky model was used to calculate the direct, diffuse and global irradiance components and projected onto all the discrete facade elements of the by means of orientation-dependent radiation computations. The angle-of incidence effects were included automatically by the radiation analysis algorithms of Ladybug. The resultant radiation matrices–stated in annual incident energy per facade element (kWh/m2) produces the primary façade-resolved irradiance input for the later performance analysis. 3.7.2 Dust and Soiling Parameterization The amount of dust built-up was modelled by a scenario-dependent soiling-loss formulation over the external secondary glazing layer. The baseline condition implements a standard exponential accumulation profile representing semi-arid deposition trends under periodic maintenance. For example, in Scenario 3 (hydrophobic coating), the dust-retention coefficient is decreased to model lower particulate adhesion while in Scenario 5 (enhanced O&M strategy) the soiling curve is periodically reset to model more frequent facade cleaning. These variations impact only the optical transmittance of the external layer; the main BIPV glazing characteristics essential remain constant across all simulations. 3.7.3 Thermal Modeling Approach To assess the PV operating temperature, the applied method was thermal balance including ambient temperature, incident irradiance, and heat transfer across the facade assembly. The ventilated air gap between the primary BIPV glazing and the external secondary one serves as a moderating cavity that increases the rate of convective heat dissipation and decreases the thermal load on PVs. In Scenario 4 (thermal-resistant layer), the thermal-loss coefficient of the external glazing is changed to reflect materials with lower solar absorptance and stability to thermal conditions. All remaining thermal parameters are kept constant to separate the effect of the secondary-layer intervention. 3.7.4 Electrical Performance Parameters and Benchmarking Electrical parameters were harmonized from all the simulations to eliminate the impact of optical, dust-related, and thermal changes. A DC-AC ratio of 1.05 and inverter efficiencies consistent with (Huawei SUN2000-110KTL-M0) units installed in the case study building were applied uniformly. Losses related to mismatch, wiring, temperature coefficients, and light-induced degradation follow the PV dataset associated with the Smart Health Tower system. Performance ratio, electrical yield, and loss distribution for the baseline configuration were benchmarked using PVsyst to prove consistency with industry-standard photovoltaic performance modeling. Electrical parameters were not changed between mitigation scenarios, confirming that observed differences in energy output rise only from façade-level optical and thermal effects introduced by the secondary glazing layer. Table 3.2 shows Each scenario was implemented by modifying a single dominant physical parameter while keeping all climatic, geometric, and electrical boundary conditions unchanged, allowing direct attribution of performance variation to the proposed secondary layer. Scenario Physical mechanism Simulation parameter explicitly modified Exact parameter setting in model Tool level Baseline (no layer) Reference case Front-surface optical properties Glass transmittance = reference (e.g., τ₀), reflectance = reference (ρ₀) Radiation + PV model Soiling loss Fixed baseline soiling loss (e.g., constant loss factor, no mitigation) PV performance Module temperature Standard temperature model (PVsyst default) PV thermal 1. optical Film Layer Reduced dust adhesion and accumulation Soiling loss factor Soiling loss reduced by fixed percentage relative to baseline (e.g., −X%) PV performance Optical transmittance Maintained at baseline value (no additional optical gain assumed) Radiation 2. Anti-UV / anti-scratch film Optical durability + surface protection Front-glass transmittance Slightly increased or stabilized transmittance (τ = τ₀ + Δτ) Radiation Long-term degradation Degradation rate set to zero / reduced PV performance 3. Hydrophobic coating Self-cleaning / reduced dust adhesion Soiling rate Lower soiling accumulation rate (slower loss recovery curve) PV performance Rain recovery efficiency Increased cleaning effectiveness (higher recovery fraction after rain) PV performance 4. Thermal-resistant layer Reduced module operating temperature Operating cell temperature Cell temperature reduced by fixed ΔT (e.g., − 5 to − 10°C) Thermal–electrical Temperature coefficient Standard power temperature coefficient retained (e.g., − 0.45%/°C) PV electrical 5. Modular design Improved maintenance and replaceability System availability Downtime losses reduced (availability factor increased) PV performance Cleaning frequency Increased cleaning frequency / reduced maintenance interval PV performance 6. Micro-CPC secondary layer Optical concentration and light redirection Incident irradiance on PV Effective irradiance multiplied by concentration factor (C > 1) Optical / PV Acceptance angle losses Included via angular loss modifier (IAM adjusted) Radiation Optical losses Fixed loss terms applied (re-emission, escape, absorption) Optical model Module temperature Temperature penalty applied due to higher irradiance Thermal–electrical 3.7.5 Simulation Workflow and Output Processing Scenario-specific soiling factors, Façade-resolved irradiance matrices, and thermal modifications were processed in the Grasshopper environment to calculate photovoltaic output at facade scale. In every mitigation scenario and module type, the workflow will compute the annual electricity generation, installed PV area and energy yield (kWh/y). Outputs are aggregated for the entire simulated facade area of 5,814.6 m², and the current 753 m² BIPV belt of the Smart Health Tower is applied as a validation reference to assess the performance of the baseline. Comparative performance indicators involve total annual yield, specific yield (kWh/m2), and relative gains compared to the baseline configuration. 3.8 Performance Evaluation Metrics and Comparative Assessment Framework To confirm a systematic and transparent assessment of the mitigation and baseline scenarios, a structured performance assessment framework is implemented. The evaluation emphasizes facade-scale photovoltaic performance and utilizes a series of quantitative indicators that are generally used in the evaluation of building-integrated photovoltaic (BIPV) systems, especially in conditions of variable climatic and operating conditions. The key performance indicators are the annual energy yield (kWh/year) which represents the total electricity being produced at the facade level and the specific energy yield (kWh/m²·year), which normalizes the production based on the active photovoltaic area and allows normalizes between scenarios with identical geometry. Furthermore, the relative performance gain (%) is computed for each mitigation scenarios relative to the baseline configuration, enabling improvements to be stated independently of absolute yield values. Performance ratio (PR) and trends in the performance of individual performance are mentioned where applicable to help in consistency of interpretation with the conventional practice of assessing photovoltaic performance. Performance ratio (PR) and loss-related trends are referenced where applicable to ensure interpretation is consistent with accepted solar performance evaluation practices. Evaluation of the simulation results uses the baseline-referenced comparison method, while the baseline case corresponds to the existing BIPV façade configuration under the same geometric, climatic, and electrical conditions. By normalizing all mitigation scenarios against this validated reference, the framework confirms that any observed performance changes can only be from modifications to the secondary layer properties, such as optical transmittance, dust-related attenuation, or thermal resistance, or concentration effects. Thus, the facade of geometry, climate inputs, discretization strategy, and electrical configuration remained constant for all scenarios to maintain methodological rigor. This controlled-variable approach separates the effect of the secondary-layer interventions and avoids confounding impacts related to system sizing, orientation, or boundary conditions. Therefore, scenario comparisons represent true performance variations due to the proposed mitigation techniques. This comparative framework highlights relative performance trends rather than absolute long-term predictions due to the inherent uncertainties involved in dust accumulation dynamics and thermal behavior of the façade. Thus, Mitigation strategies can be ranked according to their effectiveness in improving energy generation at the façade level while maintaining the applicability of the results to similar semi-arid, dust-prone settings. The defined evaluation metrics and comparison logic form the methodological basis for the results shown in Section 4 . 3.9 Verification Using the Existing BIPV Facade and cross-tools Benchmarking. The Smart Health Tower contains a built-in BIPV system where the upper part of the window band on every floor function as a photovoltaic glazing element. The current BIPV facade belt is employed as a tool-to-reality verification reference, allowing the validation of facade geometry, distribution of modules, and boundary conditions in the simulation environment. The modeled configuration replicates cumulative facade coverage, as-built PV module dimensions, and vertical placement to consistently match with the applied system. Beyond this built-system verification, another tool-to-tool verification is also done by benchmarking the baseline facade configuration against electrical performance outputs that were created with PVsyst. Key indicators such as performance ratio, annual energy yield, and loss structure are compared at an order-of-magnitude level to confirm that the façade-scale simulation results are electrically realistic and consistent with industry-standard photovoltaic performance modeling. Simultaneously, these verification steps provide confidence that the suggested simulation framework is both physically grounded in an existing building application and robust across complementary modeling tools prior to evaluating full-façade and secondary-layer mitigation scenarios. Figure 3.8 (a) (b) (c). Verification of the simulation framework. (a) PVsyst baseline performance is used as tool-to-tool electrical benchmarking. (b) PV array and inverter characteristics of the existing BIPV installation used as system reference. (c) Built-system verification of the existing BIPV façade belt integrated in the upper window band of the Smart Health Tower, used as tool-to-reality validation. 4. Results 4.1 Chapter Overview and Reporting Framework This section reports the simulation results obtained for the Smart Health Tower under the existing BIPV configuration and the proposed façade-scale enhancement scenarios. Results are reported using consistent performance indicators to ensure direct comparability across photovoltaic technologies and secondary-layer strategies. The primary indicator is the Annual electricity generation (kWh/year), while specific yield (kWh/m²·year) is used to normalize performance with respect to active photovoltaic area. For scenario-based assessment within each technology, relative gains are calculated against the full-façade, no-secondary-layer reference case. Therefore, the chapter is structured as follows: Section 4.2 reports the verified baseline performance of the existing BIPV façade belt; Section 4.3 consolidates all monocrystalline façade-scale scenarios in a single comparative table; Section 4.4 presents the corresponding polycrystalline scenarios using the same structure; and Section 4.5 provides a concise cross-technology interpretation. 4.2 Baseline Results: Existing BIPV Façade Belt (As-Built System) The baseline case corresponds to the as-built BIPV system installed on the upper window band of the Smart Health Tower and acts as the verification reference for the following scenario comparisons. Based on the data presented in the building office, the current BIPV belt generates about 321,000 kWh/year of electricity recently. To match the simulation framework with the applied system, the initial configuration of the system was recreated using the Rhino-Grasshopper model with the confirmed facade geometry and module arrangement, consisting of 900 BIPV modules covering an active photovoltaic area of 753 m². Under the same baseline configuration, the simulation produces an annual electricity generation of 321,685 kWh/year, indicating close agreement with the reported operational value and supporting the use of the baseline model as a reference for the following scenario-based evaluations. Table 4.1 Baseline performance of the existing BIPV façade belt (verification reference case), comparing reported annual production from the Smart Health Tower building office with the corresponding Rhino–Grasshopper baseline model output. Parameter As built (reported by building office) Baseline model (Rhino–Grasshopper) BIPV location Upper window band (each floor) Upper window band (replicated geometry) Number of BIPV modules 900 900 Active PV area (m²) 752.9 752.9 Annual electricity generation (kWh/year) 321,000 321,685 Specific yield (kWh/m²·year) 426.4 427.3 Agreement (model vs reported) — + 0.21% 4.3 Monocrystalline BIPV Results: Façade-Scale and Secondary-Layer Scenarios Table 4.2 shows monocrystalline BIPV performance results, including the as-built belt configuration used for model verification, the full-façade implementation without secondary layers, and a series of independently evaluated secondary-layer and optical enhancement strategies. For comparability among scenarios, the full-façade monocrystalline configuration without any secondary layer (gross window area = 5,814.6 m²) is adopted as the reference condition for reporting relative energy gains. Under the full-façade, no-layer configuration, the annual electricity generation reaches 2,478,000 kWh/year, reflecting the effect of extending PV-active glazing across the entire façade area. The application of individual secondary-layer strategies results in increased improvements in annual energy output relative to this reference case. Optical and surface-based enhancements, including UV/anti-scratch protective layers and anti-reflective (AR) optical films, produce modest gains associated with reduced reflection losses and improved surface durability. Moderate improvements are achieved by system and material level strategies, i.e., modular design of the facade and thermal-resistant coating can generate moderate advancements by moderating electrical mismatch and temperature-related performance losses. The hydrophobic coatings show a greater relative gain, which is in line with the recovery of the losses associated with soiling in dust prone climatic conditions. Maximum energy yield is achieved under the monocrystalline micro-CPC set-up, that generates 4,584,300 kWh/year, equivalent to an 85 % increase relative to the full-facade, no-layer reference. The configuration is a radically new optical collection concept and therefore seen as a system-level improvement and not a traditional secondary-layer optimization. Table 4.2 is a summary of the monocrystalline BIPV performance. The entire face configuration with no secondary-layers is used as the reference case and effects of each secondary-layer or micro-CPC added in isolation are measured separately relative to this baseline. Scenario PV area (m²) Modules Annual energy (kWh/y) Specific yield (kWh/m²·y) ΔE Secondary layer / Strategy Baseline (no secondary layer) 5,814.6 2,296 2,478,000 426.2 0.0 None 1. Optical film layer 5,814.6 2,296 2,552,340 439.0 3.0 Optical enhancement film (Anti-Reflective transmittance control) 2. Anti-UV / anti-scratch film 5,814.6 2,296 2,621,724 450.9 5.8 Protective anti-UV / anti-scratch film 3. Modular design 5,814.6 2,296 2,651,460 456.0 7.0 Modular façade layout / electrical segmentation 4. Thermal-resistant layer 5,814.6 2,296 2,725,800 468.9 10.0 Thermal-resistant / spectrally selective layer 5. Hydrophobic coating 5,814.6 2,296 2,800,140 481.6 13.0 Hydrophobic coating (soiling mitigation) 6. Micro-CPC configuration 5,814.6 2,296 4,584,300 788.4 85.0 Micro-CPC secondary optical concentrator 4.3 Polycrystalline BIPV Results: Rationale and Key Performance Indicators Besides monocrystalline systems, polycrystalline BIPV systems were also modeled to reflect cost-sensitive façade-scale applications. Due to the low cost of production, polycrystalline modules are still credible when the economic considerations affect the choice of technology. In the full-façade set-up without secondary layers (gross window area = 5,814.6 m2), the polycrystalline system yields 1,457,647 kWh/year which is taken as the reference point. The lower production compared with the monocrystalline scenario can be mainly explained by the lower conversion efficiency of polycrystalline modules (20% versus 34%), but it still sets a realistic benchmark to make a comparative evaluation. Secondary-layer and system-level approaches generate incremental advancements in yearly energy production compared to this baseline. UV/anti-scratch layers, optical films, thermal-resistant layers, modular facade design, and hydrophobic coating will result in moderate improvement by reducing reflection losses, thermal degradation, electrical mismatch, and soiling features in dust-prone climatic conditions. Optimal polycrystalline energy production is obtained in the micro-CPC setup, which is equal to 2,696,647 kWh/year which is equivalent to 85 percent higher compared to the full-facade no-layer reference. Like monocrystalline, this configuration is an optical improvement on the system level rather than conventional secondary-layer optimization. By using the same facade geometry, environmental condition, and scenario definitions, the research makes it possible to directly and consistently compare monocrystalline and polycrystalline BIPV technologies to make informed design decisions in different cost-performance priorities. Table 4.3 Polycrystalline BIPV facade-scale results in the baseline case, secondary-layer and micro-CPC with relative gains to the full-facade no-layer case. Scenario PV area (m²) Modules Annual energy (kWh/y) Specific yield (kWh/m²·y) Gain vs full-façade no-layer (%) Secondary layer / Strategy Baseline (no secondary layer) 5,814.6 2,296 1,457,647 250.7 0.0 None 1. Optical film layer 5,814.6 2,296 1,501,376 258.2 3.0 Optical enhancement film (AR / transmittance control) 2. Anti-UV / anti-scratch film 5,814.6 2,296 1,542,191 265.2 5.8 Protective anti-UV / anti-scratch film 3. Modular design 5,814.6 2,296 1,559,682 268.2 7.0 Modular façade layout / electrical segmentation 4. Thermal-resistant layer 5,814.6 2,296 1,603,412 275.8 10.0 Thermal-resistant / spectrally selective layer 5. Hydrophobic coating 5,814.6 2,296 1,647,141 283.3 13.0 Hydrophobic coating (soiling mitigation) 6. Micro-CPC configuration 5,814.6 2,296 2,696,647 463.8 85.0 Micro-CPC secondary optical concentrator 5. Discussion The findings verify that efficiency of BIPV windows across semi-arid and dust-prone climates are intensely affected by façade-level optical, thermal, and soiling-related aspects. The recalculated absolute energy outputs emphasize the necessity of system-level assumptions, facade coverage, and secondary layer integration in evaluating the actual impact of window-integrated photovoltaic on building energy demand. When operating under the no-secondary-layer full-facade with a monocrystalline BIPV system, the system generates 2.48 GWh/year, whereas the polycrystalline system generates 1.46 GWh/year. Such differences are a result of the greater intrinsic conversion efficiency of monocrystalline technology at identical geometric and climatic conditions. Regardless of this certain gap, the two technologies demonstrate very stable relative reactions to the interventions of secondary layers, which means that the observed improvement in performance is largely determined by facade-level environmental interactions and not only by cell technology alone. Relative energy gains of both secondary-layer technologies range from + 3% to + 13%. Optical Film improvements and anti-UV/anti-scratch layers give modest improvements by stabilizing the surface transmittance and reducing optical degradation. Modular facade design can provide intermediate gains by enhancing system availability and electrical segmentation, whereas thermal-resistant layers are able to provide even greater benefits by decreasing temperature-driven efficiency losses caused by high irradiance and dust-enhanced surface heating. Hydrophobic coating is one of the non-concentrating strategies that provide the highest incremental gains, which highlights the importance of soil reduction in the environment with low rainfall and high persistent airborne dusts. The practical value of these findings is understood better when BIPV electricity generation is associated with the operational energy demand of the Smart Health Tower. Building documents show that electricity use reaches about 759,000 kWh in July, showing the peak demand period mainly due to cooling loads. Using a simple average-month estimation, the baseline monocrystalline BIPV setup (2,478,000 kWh/year) will provide approximately 206,500 kWh in July, which will supply about 27 % of the towers’ July power demands. In the case of the hydrophobic coatings, the estimated production in July is 233,300 kWh which serves about 31% of the July demand. At the micro-CPC setting, estimated July production is 382,000 kWh which is equivalent to about 50% of the July electricity demand. In the case of the polycrystalline system, the baseline system will provide about 16% of July demand, which rises to 18 % when using hydrophobic coating and reaching about 30% under the micro-CPC configuration. Although these estimates do not account for hourly or monthly variations, they show that facade-integrated BIPV windows may serve as a significant share of peak-period electricity demand in large health facilities, especially when more sophisticated strategies of secondary-layer or optical concentration are used. The micro-CPC configuration is a type of intervention which is fundamentally different from the surface-based secondary layers. By adjusting the optical collection mechanism and concentrating incident radiation to the photovoltaic elements, micro-CPC systems generate a step-change in energy production (around + 85%) for both technologies. Therefore, they must be understood as facade-integrated optical systems rather than incremental dust-reduction measures, preserving an easy separation between facade optimization and system-level redesign. In general, the findings confirm the primary premise of this research: that meaningful enhancements of BIPV window performances can be enhanced significantly using facade-integrated secondary layers, which address optical, thermal, and soiling-related losses in dust-prone regions. Incremental strategies offer robust and scalable improvements whereas system-level optical concentration is much more promising in terms of offsetting building electricity demand but carries additional design costs. Collectively, these results offer an organized framework for choosing BIPV window advancement techniques according to performance aims, environmental conditions, and design priorities in large-scale building applications. 6. Conclusion The present study explored the facade-scale performance of building-integrated photovoltaic (BIPV) windows when based in semi-arid, dust-prone environments, and especially including the role of secondary-layer strategies in reducing optical, thermal and soiling-related losses. By employing the Smart Health Tower as the real-world case study, a simulation-based model was used to compare monocrystalline and polycrystalline BIPV window efficiency in same geometric and climatic environment. The findings indicate that facade integrated secondary layers offer significant and reliable enhancements in BIPV window performance. In both technologies, incremental strategies achieve relative annual energy gains of up to ≈ 13%, with hydrophobic coatings indicating the strongest impact among non-concentrating solutions. Thermal resistant layers also improve performance by eliminating efficiency losses due to temperature, whereas optical films, protective layers and modular facade configurations contribute to more reasonable but robust improvements that support long-term operational stability. The entire-facade monocrystalline BIPV system will produce an annual electricity production of ≈ 2.48 GWh compared to ≈ 1.46 GWh with the polycrystalline configuration. Despite this discrepancy, both technologies show equivalent proportional response to secondary-layer interventions, demonstrating that the efficacy of performance enhancement strategy is controlled mainly by façade-level environmental interaction instead of photovoltaic cell type. This proves the technical feasibility of polycrystalline BIPV windows for cost sensitivity on the facade applications when paired with suitable secondary layers. In terms of building operation, the baseline monocrystalline BIPV facade provides about 27% of the Smart Health Tower’s July electricity demand (≈ 759,000 kWh), with hydrophobic layer rising to 31%, and reaching ≈ 50% with the micro-CPC setup, the percentage rises to 50 per cent based on an average-month approximation. The values show that optimized BIPV windows are practically capable of offsetting a significant portion of electricity consumption in large healthcare facilities during the peak period. The micro-CPC system results in a step-change increase in yielding energy about + 85%, which is a system level optical intervention rather than an increase in surface treatment. This strategy has much greater performance potential but also brings greater design complexity which must be addressed at the architectural and facade-integration level. Overall, the results prove that secondary layers are not an auxiliary addition but an essential element of efficient BIPV windows in dust prone areas. To address environmental degradation mechanisms, facade-integrated secondary layers allow BIPV windows to achieve reliable, scalable, and context- responsive performance, enhancing their role as a meaningful contributor within the building energy systems rather than a purely architectural feature. Declarations Author Contributions Statement : I.S. designed and created this research, established the methodology, carried out the simulations and analysis, and written the original manuscript and S.Y.B. supervised the research, offered conceptual guidance throughout the research, and assisted with the critical revision of the manuscript. Both authors revised and approved the final version of the manuscript. Additional Information: Funding: The authors received no specific funding for this work. 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Reddy, P., Gupta, M. V. N. S., Nundy, S., Karthick, A. & Ghosh, A. Status of BIPV and BAPV System for Less Energy-Hungry Building in India—A. Rev. Appl. Sci. 10 , 2337. https://doi.org/10.3390/app10072337 (2020). Ghaleb, B., Khan, M. I. & Asif, M. Application of PV on Commercial Building Facades: An Investigation into the Impact of Architectural and Structural Features. Sustainability 16 , 9095. https://doi.org/10.3390/su16209095 (2024). Liu, X. & Wu, Y. Design, development and characterisation of a Building Integrated Concentrating Photovoltaic (BICPV) smart window system. Sol. Energy . 220 , 722–734. https://doi.org/10.1016/j.solener.2021.03.037 (2021). Singh, M., Rana, S. & Singh, A. K. Advanced nanomaterials utilized as top transparent electrodes in semi-transparent photovoltaic. Colloid Interface Sci. Commun. 46 , 100563. https://doi.org/10.1016/j.colcom.2021.100563 (2022). Castillo, M. S., Liu, X., Abd-AlHamid, F., Connelly, K. & Wu, Y. Intelligent windows for electricity generation: A technologies review. Build. Simul. 15 , 1747–1773. https://doi.org/10.1007/s12273-022-0895-y (2022). Younis, A., Cotfas, P. A. & Cotfas, D. T. Systematic indoor experimental practices for simulating and investigating dust deposition effects on photovoltaic surfaces: A review. Energy Strategy Reviews . 51 , 101310. https://doi.org/10.1016/j.esr.2024.101310 (2024). Liu, X. & Wu, Y. A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control. ARIN 1, 10. (2022). https://doi.org/10.1007/s44223-022-00009-6 Ghamari, M. & Sundaram, S. Solar Window Innovations: Enhancing Building Performance through Advanced Technologies. Energies 17 , 3369. https://doi.org/10.3390/en17143369 (2024). Bao, Y. & Xiang, C. Integration of BIPV technology with modular prefabricated building - A review. J. Building Eng. 102 , 111940. https://doi.org/10.1016/j.jobe.2025.111940 (2025). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 05 Mar, 2026 Reviews received at journal 05 Mar, 2026 Reviewers agreed at journal 04 Mar, 2026 Reviewers agreed at journal 04 Mar, 2026 Reviews received at journal 26 Feb, 2026 Reviewers agreed at journal 18 Feb, 2026 Reviewers agreed at journal 13 Feb, 2026 Reviewers agreed at journal 11 Feb, 2026 Reviewers invited by journal 11 Feb, 2026 Editor invited by journal 10 Feb, 2026 Editor assigned by journal 09 Feb, 2026 Submission checks completed at journal 09 Feb, 2026 First submitted to journal 06 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8807699","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":591005042,"identity":"aff846b3-dacc-43b5-a819-ecc41a75938f","order_by":0,"name":"Isra Shorsh¹","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAUlEQVRIiWNgGAWjYBACNiidACZ5DGzkgCRJWgrSjAlqgQGolg+HExsIaeHjP/vwA2PO4Tz+aacTH7wxOJy+4fjZgw8+MNjJ6TbgcJhEurEE47bDxRK3czcbzjFIz91wJi/ZcAZDsrHZAVxa2BhAWhIbbuduk+YxsM7dcCDHTJqH4UDiNlxa+I8x/wBpmX87d/tvHgPmdIPzbwhoYUhjA9uyAWgLM4+Bc4LBDUK2SKSxWSRuS0/cCPSL5ByDNMOZN94YG84wwO0X+f5jzDc+brNOnHc7d+OHN39s5PnO5xg++FBhJ4dLCxgkIHMUwCoN8CjHtLeBFNWjYBSMglEwEgAAjONe+nqHopQAAAAASUVORK5CYII=","orcid":"","institution":"Salahaddin University-Erbil","correspondingAuthor":true,"prefix":"","firstName":"Isra","middleName":"","lastName":"Shorsh¹","suffix":""},{"id":591005043,"identity":"be3e3f66-39af-4038-baf1-c22cc7b4edc3","order_by":1,"name":"Salahaddin Yasin Baper¹","email":"","orcid":"","institution":"Salahaddin University-Erbil","correspondingAuthor":false,"prefix":"","firstName":"Salahaddin","middleName":"Yasin","lastName":"Baper¹","suffix":""}],"badges":[],"createdAt":"2026-02-06 13:38:50","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8807699/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8807699/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102805483,"identity":"78192ac1-9e8a-4c1d-a341-1a5390c42e9f","added_by":"auto","created_at":"2026-02-16 23:48:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":329581,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure2.1.\u003c/strong\u003eClassification of Window system\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/cb2f8b72f13cf4d593be33c0.png"},{"id":102963086,"identity":"60db21fe-a6ca-4c1a-b494-2c48576fd350","added_by":"auto","created_at":"2026-02-19 04:13:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":366765,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.1. \u003c/strong\u003edisplays the overall framework of the research, demonstrating the combination of the case study of the Smart Health Tower, simulation workflow along with secondary-layer BIPV strategies and the performance evaluation criteria adopted in this study.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/a9b53a5f9e8fee6ef2b5b5b8.png"},{"id":102805485,"identity":"d75f719a-a19a-4145-8602-dfa0e91e138d","added_by":"auto","created_at":"2026-02-16 23:48:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1244660,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.2. \u003c/strong\u003eSmart Health Tower in Sulaymaniyah, showing its curved glazed façade and the upper BIPV belt used as the reference for geometric reconstruction.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/2263dd74498425a93549f571.png"},{"id":102805487,"identity":"cbbefd75-8e8f-4e91-a7ee-fb6f19e98b99","added_by":"auto","created_at":"2026-02-16 23:48:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":228403,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.3.\u003c/strong\u003e Recreated 3D model of the Smart Health Tower showing the façade configuration used in this study. The dark green horizontal belt or band illustrates the building’s actual transparent BIPV application, while the light green glazing surfaces show the simulated extension to a full-façade BIPV envelope.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/dbf11b32cd17d1eff1391c95.png"},{"id":102962861,"identity":"a741e882-7eac-4790-99fd-43741c1f5656","added_by":"auto","created_at":"2026-02-19 04:11:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":382178,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.4.\u003c/strong\u003eThree-dimensional solar-path visualization for Sulaymaniyah, showing seasonal sun positions around the Smart Health Tower. Yellow spheres represent selected hourly sun positions, while the connecting vectors indicate the direct solar ray’s incident on the curved façade. This model demonstrates the annual solar exposure pattern used to drive façade-level irradiance analysis.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/0f08b5afb834c784be9cb9b2.png"},{"id":102962669,"identity":"6143d12c-8518-4cf4-9347-1c22a1e23de5","added_by":"auto","created_at":"2026-02-19 04:10:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":359018,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.5.\u003c/strong\u003e Top-view solar-path diagram for the case study, showing the azimuthal distribution of annual sun positions. The yellow sun markers and radial vectors are used to show the intersection points of the direct beam radiation on the tower footprint which can be used as inputs of orientation-specific irradiance to the simulation workflow.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/2124279218e15563afa12583.png"},{"id":102805488,"identity":"9b42c58a-7705-45d6-9929-3dae562957b5","added_by":"auto","created_at":"2026-02-16 23:48:46","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":192716,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.6.\u003c/strong\u003e A representation of the proposed facade-integrated BIPV window assembly with externally mounted second layer of glass to reduce dust, enhance thermal performance, and increase optical performance developed as a part of this study.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/3b4975bb48e0067366575f22.png"},{"id":102963098,"identity":"d6f1a8ef-f977-49d0-ae81-c6f138c9a5f6","added_by":"auto","created_at":"2026-02-19 04:13:30","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":612789,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.7.\u003c/strong\u003e Facade-level application and scenario parameterization of the secondary-layer represented the dust mitigation measures and performance enhancement strategies.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/2773294c58ff1bcc1698e6ba.png"},{"id":102805490,"identity":"81a7b5ff-b3ec-4371-bfe7-039ba2aade63","added_by":"auto","created_at":"2026-02-16 23:48:46","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":928176,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.8 (a) (b) (c). Verification of the simulation framework.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(a) PVsyst baseline performance is used as tool-to-tool electrical benchmarking.\u003cbr\u003e\n(b) PV array and inverter characteristics of the existing BIPV installation used as system reference.\u003cbr\u003e\n(c) Built-system verification of the existing BIPV façade belt integrated in the upper window band of the Smart Health Tower, used as tool-to-reality validation.\u003c/p\u003e","description":"","filename":"3.8.png","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/d41c03b81f044456a3e1765f.png"},{"id":103056561,"identity":"55c6ec21-6cd7-42df-8452-8ba2500e9be2","added_by":"auto","created_at":"2026-02-20 09:15:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6530028,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8807699/v1/035ab78a-f886-481b-8fc7-f9854bc5a6fa.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Optimizing BIPV Windows in Dust-Prone Regions: Enhanced Strategies for Energy Efficiency in Semi-Arid Climates","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBuilding-Integrated Photovoltaics (BIPV) have become a priority in sustainable building designs due to their ability to replace conventional fa\u0026ccedil;ade materials with energy-generating systems, particularly in the form of photovoltaic windows that integrate electricity generation, daylighting, and solar control into one architectural element, Building-Integrated Photovoltaics (BIPV) have become a priority of the sustainable building design. As urbanization increases and buildings grow taller, fa\u0026ccedil;ade surfaces provide significantly more area for solar harvesting compared to rooftops, making them essential for achieving onsite renewable energy targets in dense cities [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. This is especially relevant in semi-arid climates, with extremely high solar irradiation, where buildings face equally high cooling loads, which calls the need of technologies in facades with the ability to minimize heat gain whilst generating renewable energy [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In these areas BIPV windows have a twofold environmental benefit, reducing the energy use of the HVAC system and utilizing abundant sunlight in large amounts, yet the actual performance of the system is limited by the environmental elements that are not yet addressed in literature or practice. Dust accumulation is one of the most severe issues that restrict the performance of BIPV windows in semi-arid and dusty climate conditions. The deposition of dust on photovoltaic glazing causes significant optical losses, because the particulates suspended in the air are scattered, absorbed and block solar energy entering the photovoltaic cells, thereby reducing the number of photons reaching the photovoltaic cells [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. As previously indicated by experimental studies, nonlinear reductions of short-circuit current (Isc), maximum power (Pmax) and total efficiency are observed in all cases even by very low levels of dust density both through optical shading and thermally induced degradation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Gholami et al. demonstrated that up to 25 percent of transmission coefficients could be lowered by dust deposition on tilted glazing with sensitivity being heavily dependent on the tilt, orientation and local wind direction patterns [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Effects are even worse in desert adjacent areas, with Sadat et al. reporting efficiency loss of up to 98 percent in desert areas of Iran during heavy deposition, indicating the high sensitivity of PV glazing to semi-arid climate [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These losses are ever worse by the fact that vertical facades do not get natural cleaning by rainfall as much as roof-mounted systems, resulting in acceleration and the continued accumulation of dust all year round [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The problem is further aggravated by the interactions of dust, heat and optical performance. Dust accumulation increases operating temperature of modules (by capturing solar energy) and blocking uniform heat dissipation (by blocking uniform cooling of heat) and therefore reduces efficiency of temperature-dependent thin-film and semi-transparent BIPV systems [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. According to Shi and Zhu, one of the essential drawbacks of BIPV windows is thermal loading because higher operating temperatures contribute to greater thermal conductivity to the interiors, higher U-value, and lower electrical output at the same time [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. These two penalties make semi-arid climates to be highly challenging to BIPV glazing where dust depositions and extreme ambient temperatures co-exist. The optical and electrical performance has greatly enhanced with technological advances in the design of BIPV windows but none of them deals directly with dust accumulation. Theoretically, transparent windows with photovoltaic characteristics can be created using transparent electrodes, e.g., AgNW/AZO multilayers, and were demonstrated to be able to daylight, de-ice, and harvest solar energy [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Moor et al. have produced Luminescent solar concentrator (LSC) windows that have high visible transmittance and power outputs to 50.5 Wp and have proven to be viable in facade integration [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Likewise, Vasiliev et al. introduced spectrally selective energy-harvesting windows that are highly transparent with the utilization of CIS PV modules and luminescent materials to maximize the performance of the windows under the diffuse light [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The potential of concentrator-based BIPV windows is also significant; Xuan et al. have shown that lens-walled CPC windows can be expected to exceed daylight uniformity, reduce glare and provide more than six times more active areas of illumination compared to conventional semi-transparent PV glazing [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These new advancements show an outstanding development of integrating aesthetics, energy production and visual comfort in BIPV windows. Nevertheless, current BIPV window technology nearly lacks dust mitigation strategies even though dust has been identified as one of the most critical and recurring challenges in PV operation by several reviews. According to Kazem et al., dust was able to decrease the PV efficiency by up to 80 percent based on the climate and dust properties, a fact that highlights the urgency of incorporating dust-resistant designs instead of just using external cleaning interventions [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Gupta was also able to find dust as an unavoidable environmental stress factor in many climates and emphasized the fact that the intensity of losses caused by dust is dependent upon the particle morphology, moisture content, the angle of inclination and exposure duration [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Cleaning technologies Can be either manual washing, mechanical brushes, or electrodynamic screens, which are usually not feasible to high-rise BIPV facades either due to cost, accessibility, safety considerations, or lack of compatibility with architectural requirements [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Hydrophobic nanocoating: (self-cleaning layer of SiO2) as tested by Alamri et al. can enhance power output by up to 15 percent over dusty panels, but durability, optical clarity and long-term environmental performance are an issue in large facade applications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Overall, even though there are current solutions that would partially alleviate the problem of dust, none of them offer a long-term and integrated, facade-compatible solution to the problem that would be applicable in semi-arid regions. Facade and glazing Parallel studies of facade and glazing performance have indicated that the energy efficiency of multi-layered facade systems or optical improvements can be considerably enhanced with appropriate integration. Attoye et al. have discovered that the electrical performance of BIPV facade layers (such as glass geometry, coverings, and distance between PV cells) can be optimized through customization to increase electrical performance by up to 80 percent, indicating the significant value of compositional facade modification [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Similarly, the optimization of the facade design in the hot climate underlines the need to combine the shading and glazing technologies with the PV systems to decrease the cooling load and improve the overall performance of the building [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These results are a strong affirmation towards the idea of introducing a secondary or protective (optical) layer in front of BIPV windows as an element of facade customization and not an external cleaning device. Moreover, the research on solar concentrators and optical enhancement systems is strong evidence that additional optical layers can improve PV power output in the case of diffuse or scattered light- exactly the optical conditions created by dust. According to Rashid, the analysis of Fresnel lens systems enhances the concentration of the sun and thermal collection in the different atmospheric conditions, indicating that they perform well even in the partially obscured irradiance [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The CPC windows used by Xuan et al. also improve light capture with oblique angles, while Vasiliev et al. showed that LSC windows are stable to non-ideal lighting conditions due to their ability to work with an orientation or tilt angle [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Since dust elevates the diffuse fraction of solar radiation, the concepts of the concentrators are directly relevant in reducing the optical losses associated with dust in BIPV windows. Despite evident synergies, there is no literature that combines a secondary optical layer/protector or concentrator as a dust-reduction measure on BIPV windows in semi-arid environments. This can be considered a critical research gap at the intersection of fa\u0026ccedil;ade engineering, photovoltaic performance, and environmental resilience. It is important to address this gap to achieve the maximum potential of BIPV windows in areas where dust, heat, and high solar exposure coexist. Consequently, this study will design the BIPV windows appropriate to dust-prone semi-arid regions by assessing the efficiency of a secondary-layer/protector or concentrator that is installed in front of the photovoltaic glazing. The suggested system will aim at (1) lowering dust deposition on the glass surface, (2) increasing optical capture at diffuse irradiance, and (3) preserving high transmittance of visible light and thermal comfort. This research merges conclusions of dust behavior, concentrator optics, and BIPV window technologies to propose a novel fa\u0026ccedil;ade-integrated solution that innovates energy efficiency in unfavorable environmental conditions.\u003c/p\u003e"},{"header":"2. Literature Reviews","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Introduction to Building-Integrated Photovoltaics (BIPV) and Facade Implementation.\u003c/h2\u003e \u003cp\u003eBuilding-Integrated Photovoltaics (BIPV) represent a type of photovoltaic system in which traditional building envelopes are replaced and simultaneously generate electricity, which is a multifunctional solution to enhancing building energy performance [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In contrast to the building-Applied Photovoltaics (BAPV), which are mounted on existing surfaces, BIPV systems are used as structural elements in the form of glazing, cladding, louvers, and shading equipment, in addition to both structural and environmental functions [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The increased demand for energy-efficient and sustaining buildings has increased the implementation of BIPV solutions especially in high-solar-available areas, where it provides a direct pathway to reduce grid dependance and carbon footprint in operation [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Facade-based BIPV is one of the envelope-integrated applications that have received the greatest attention because it has the potential to turn the large amounts of vertical surfaces of buildings into useful energy-producing systems [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. This is more applicable in urban settings and high-rise typologies, whereby rooftop space is minimal and cannot support huge energy demands. Photovoltaics that are integrated on the facade can also be predictably incorporated into the architecture which provides the designers with opportunities to modulate transparency, aesthetics, orientation and customization of modules to suit the building\u0026rsquo;s needs [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Recent developments have developed semi-transparent photovoltaic glazing, colorful modules, and controllable facade geometries, which show an even greater improvement of the architectural viability and visual acceptability of BIPV [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Facade-integrated BIPV is more important in hot and semi-arid areas, where it can compensate for massive cooling loads beside harvesting massive solar energy throughout the year [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Nevertheless, the operation of facade-mounted PV, in particular, vertical glazing systems, is highly sensitive to environmental factors including dust layers, irradiance fluctuations and thermal loads that require further research and optimization techniques discussed in later sections below.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Semi-Transparent and Transparent BIPV Window Technologies\u003c/h2\u003e \u003cp\u003eSemi-transparent and transparent BIPV windows are the advanced type of photovoltaic glazing systems designed to make use of daylight, control solar gains, and produce on-site electricity by means of selective spectral absorption [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Semi-transparent designs are normally based on controlled cell spacing, patterned deposition or partial absorber coverage, allowing a calibrated balance between visible-light transmittance and electrical performance while maintaining architectural appearance [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Their efficiency is controlled by spectral selectivity, where ultraviolet and near infrared wavelengths are transformed into electricity as the visible spectrum goes through the glazing and daylight can be used without serious luminance obstruction [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Transparent BIPV technologies go beyond this principle with the luminescent solar concentrator (LSCs) which absorbs non-visible light and then re-emits photons towards edge-mounted PV cells and sustains optical clarity with dispersed electrical generation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Other strategies use spectrally selective coating, which transfers the visible light but directs the UV/NIR to internal layers of active photovoltaic material, enabling complete transparency without lowering the energy harvesting potential [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Recent advances in transparent conductive electrode such as AgNW- and nanoparticle-based films, further increase optical-electrical efficiency since they enable the flow of charges without causing visual artifacts [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. All these technologies together create a varied design landscape where the transparency, power density, and thermal performance should be balanced based on the climatic and facade-related environment.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Climatic Stressors and Dust Deposition Dynamics in Semi-Arid Regions\u003c/h2\u003e \u003cp\u003eSemi-arid areas have a specific set of environmental stress factors, which increase the operational difficulties of photovoltaic glazing systems. These types of climates have consistently high solar irradiance, low moisture content of the atmosphere and low levels of annual precipitation making ordinary deposits of particulates to stay on the surfaces of facades over a long period without natural cleaning periods [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The clear-sky predominance conditions also create a radiation field that dominates the intense beam components, while varying wind velocities and turbulence patterns redistribute the aerial particulates in the building envelope in extremely localized deposition regimes [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Vertical Fa\u0026ccedil;ade-integrated PV windows are especially exposed to these dynamics when fa\u0026ccedil;ade-mounted systems behave differently to atmospheric flow fields than those roof-mounted PV; wind-induced sediment, facade scale vortices and Building-related pressure variations interact to affect deposition rates and spatial uniformity [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Both macro and micro mechanisms control dust depositions in these areas. At the macro scale, mineral aerosols as the result of soil erosion, construction debris, vehicular upheavals, and long-range transported dust clouds are the sources of particulates, which produce a range of particles in the form of fine silicates and aggregate mineral particulates that have high optical and adhesive characteristics [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. On a micro level, adhesion of the particles is dictated by electrostatic interactions, capillary bridges created during low humidity and surface-energy differences between dust minerals and glazing materials, which favor long-term fouling on photovoltaic surfaces [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. When deposited, small particulates infiltrate micro-textures or irregularities in coating and cannot be removed by natural airflow to form optically dense layers that could change spectral transmission profiles, and angular distributions of incident radiation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Moreover, the absorptive properties of mineral dust amplify localized surface temperature and exacerbate thermal loading on PV-glazing layers, which exacerbates electrical degradation and heat transfer to the building interior [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. These climatic and deposition processes in combination demonstrate why BIPV windows in semi-arid climates should be designed with optimization techniques that help mitigate the effects of particulate adhesion, spectral distortion, and thermally induced loss of performance as well.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Impact of Dust on PV and BIPV Window Performance\u003c/h2\u003e \u003cp\u003eThe collective effect of dust depositions is the degradation of photovoltaic glazing which disrupts its optical, electrical, and thermal mechanisms, resulting in the loss of system efficiency [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Transmittance is reduced by particulate layers, which absorb and scatter incident radiation, as well as disrupting spectral distributions needed to achieve effective energy harvesting in semi-transparent and transparent PV windows [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. These optical losses are directly converted to electrical losses and result in disproportional losses in short circuits and maximum power output even in the presence of moderate soiling [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Also, mineral dust leads to surface absorption and increases PV-glazing temperature, elevates resistive losses and challenging operational stability in the high-irradiance settings characteristic of semi-arid climates [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. These combined impacts underscore the need to adopt specific mitigation strategies regarding BIPV facades.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Dust Mitigation Strategies and Their Practical Limitations\u003c/h2\u003e \u003cp\u003eThere is a variety of dust-reduction strategies studied to be applied to photovoltaic systems, with most of them being operationally or technically inapplicable to BIPV windows integrated into the facade. Optical clarity can be temporarily restored by conventional methods such as manual or water-based cleaning, which is expensive, labor-intensive, time-consuming and unfeasible to use in high-rise facades of semi-arid areas where rapid re-accumulation is evident, and water scarcity is a severe constraint [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Likewise, automated and robot cleaning machines need mechanical rails or external support that do not fit within the structural and aesthetic limits of transparent glazing systems, limiting their application to BIPV installations [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Surface-Mitigation approaches are most widely investigated. Hydrophobic nano-coatings prevent adhesion of particulate matter by changing the surface free energy thereby allowing partial self-cleaning during dew cycles or light rains and unlike; however, their long-term effectiveness is undermined by UV degradation and abrasion by mineral dust, requiring periodic reapplication [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Indirect mitigation such as anti-UV and anti-scratch layers, which maintain surface smoothness and optical stability because micro-abrasions and UV-related polymer degradation is known to raise dust anchoring sites and accelerate fouling of PV glazing [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, these layers alone are not capable of significantly lowering particulate depositions and their protective effects weaken extended environmental exposure. Maintenance operational (O\u0026amp;M) strategies also represent another mitigation avenue and research results indicate that optimized zone-specific cleaning intervals can mitigate performance losses better than standardized schedules [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Nonetheless, the mitigation of O\u0026amp;M is limited by access, safety, and cost of facades at the building scale. Although these methods are partial, they are not a long term, passive, or facades friendly solution. This gap has prompted the investigation of new secondary layers- such as concentrator films, micro-CPC sheets and thermal-resistant materials that combine dust shielding with optical or thermal development benefits functions, showing a more holistic approach to optimize BIPV windows in semi-arid climates [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Thermal-Responsive Glazing Materials Relevant to BIPV Optimization\u003c/h2\u003e \u003cp\u003eThermally adaptive glazing materials such as nanoparticle-enhanced coatings, thermotropic polymers, and Phase-change layers, provide passive mechanisms of solar heat gain, stabilizing surface temperatures in high-irradiance conditions [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. These materials change the transmittance or scattering at different temperatures or spectral activations and thus reduce overheating in PV-integrated glazing and eliminate efficiency loss due to thermal effects [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Their ability to lower thermal load without blocking visible light transmission gives them a conceptual basis to be used in thermal-resistant protective layers in optimizing BIPV strategies in climates where dust load increases surface heating [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Optical Concentrator Technologies Applicable to BIPV Windows\u003c/h2\u003e \u003cp\u003eTechnologies of optical concentrators provide a viable way of improving the performance of facade-based photovoltaics by controlling the angular and spectral distribution of incident solar radiation. Compound parabolic concentrators (CPCs), along with their variations-CCPC and RACPC geometries, are non-imaging systems that are developed to redirect oblique and diffuse irradiance to photovoltaic surfaces to enhance the light capture in circumstances where the direct irradiance is reduced or is irregularly distributed [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The fact that they have an acceptance-angle flexibility makes them especially applicable in semi-arid conditions, where dust-filled atmospheres enhance the diffuse component of the solar radiation and diminish the strength of the direct beam irradiance [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Another type of optical enhancers is luminescent solar concentrators (LSCs) which are non-visible wavelengths via embedded fluorophores and re-emit photons at the edge-mounted photovoltaic components to allow transparent or semi-transparent glazing designs with distributed electrical productions [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. LSC or hybrid concentrator systems use spectrally selective coatings to further refine the flow of optical routing by filtering visible while directing UV-NIR content to PV absorbers without compromising architectural transparency energy yield [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Fresnel and Holographic type of concentrators make these principles more applicable in terms of wavelength-specific light steering and compact optical concentration, making possible integration as secondary protective layers on fa\u0026ccedil;ade glazing [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In general, these elements provide a conceptual framework for protective layers that serve two functions at once: protecting BIPV glazing from dust deposition and providing an improvement in irradiance capture.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClassification of Optical Concentrator Technologies for BIPV Windows\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcentrator Type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOperating Principle\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eKey Functional Role in BIPV Windows\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTypical Materials\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompound Parabolic Concentrator (CPC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWide-angle non-imaging collection and redirection of incident light.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBoosts irradiance capture and energy yield with minimal impact on outward visibility.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAluminum-coated or silver-coated reflective surfaces; UV-stable polycarbonate or acrylic housings.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLuminescent Solar Concentrator (LSC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsorbs non-visible wavelengths and guides re-emitted light to edge PV cells.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEnhances spectral utilization and improves daylight uniformity while maintaining transparency.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePMMA or polycarbonate matrices doped with organic dyes, quantum dots, or rare-earth phosphors.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMicro-Optic Arrays (Lenses/Prisms)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMicro-structured refraction or diffraction to steer sunlight.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSupports improved indoor visual comfort and more uniform fa\u0026ccedil;ade illumination.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMolded PMMA, polycarbonate, glass micro-lens sheets, or nano-imprinted optical polymers.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e2.8 Fa\u0026ccedil;ade Design, Customization, and Multi-Layer Optical Systems\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eThe photovoltaic systems that are integrated into facade operate in very limited architectural and environmental settings and therefore geometric customization and multi-layer configurations are necessary to optimize their performance. Customization approaches, such as the ability to adjust cell spacing, glass layering, thickness of the substrate, and facade geometry allow designers to customize optical transmission as well as photovoltaic productivity to the specific building orientations and the urban environment [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. These geometric and compositional adjustments make BIPV facades balance architectural requirements with electrical functionality by regulating shading effects, daylight penetration, and the ability to selectively regulate solar gains [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. This is further enhanced by multi-layer facade systems such as double-skin systems and composite glazing stacks which comprise functional interlayers that alter spectral transmission, thermal behavior or surface interactions but do not affect structural integrity [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These layered arrangements facilitate differentiated optical pathways and thermal buffering impact and provide prospects of incorporating other protective or optical features at the facade boundary. In this context, the idea of a secondary layer (i.e., protective film, micro-optic sheet, and concentrator element) fits well into current facade engineering practice and offers viable design options to reducing dust deposition, to redistribute incident radiation, and to increasing the stability of performance of BIPV windows in semi-arid climates.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e2.9 Research Gap and Rationale\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eExisting studies on BIPV windows have little insight into their performance in semi-arid and dust prone climates where the accumulation of dust has a strong influence on optical transmission and thermal loading [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Current dust-reduction measures, including hydrophobic coating, anti-UV coating and standard cleanings, have inconsistent longevity and do not apply well to transparent facade applications [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Even though Optical concentrators and protective layers have not been assessed together, their mutual potential to increase irradiance capture and reduce glazing exposure to dust has not been systematically analyzed in BIPV window systems [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Additionally, none of the previous studies applies an integrated workflow involving facade discretization, irradiance modeling, dust-loss characterization, and multi-scenario PV simulation. These gaps are the reason to consider comprehensive secondary-layer strategies to improve flexibility and energy performance of BIPV windows in semi-arid dust climates.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Methodology","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Overview of the Methodological Framework\u003c/h2\u003e \u003cp\u003eThe research uses a multi-stage methodological approach that aims to assess the functionality of a complete BIPV window system in a semi-arid environment and determine the effect of different dust-reduction measures. The methodology incorporates four fundamental components, which include geometric reconstruction of the case-study facade, climate-based solar irradiance modelling, characterization of dust-losses, and assessment of photovoltaic energy-yields. The entire facade of Smart Health Tower is 5,814 m\u0026sup2; and it is discretized into orientation-dependent segments to capture different solar exposure of the building envelope. The incident irradiance on each segment of the facade is simulated using the hourly climatic conditions featuring sun geometry, sky conditions, and vertical-surface behavior. These irradiance values are then applied based on the dust related attenuation factors and temperature-dependent performance to represent the semi-arid soiling conditions. The irradiance and loss parameters after the processing are then used to estimate annual photovoltaic output to make a consistent comparison of the baseline configuration with the six mitigation scenarios. This combined framework certifies that geometric, climatic, optical, and electrical characteristics of facades-integrated photovoltaics are assessed in a coherent manner, providing an analytical basis of investigating scenario-based studies in subsequent sections.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Case Study Building and Fa\u0026ccedil;ade Geometry\u003c/h2\u003e \u003cp\u003eThe Smart Health Tower in Sulaymaniyah has been used as case study to perform this research because it is a fully glazed, high-rise healthcare building located in the semi-arid area with high solar radiation, high concentration of airborne particulate matter, and low rainfall. The building includes an actual, operational BIPV system that includes 900 semi-transparent monocrystalline panels mounted on the two curved faces of the building, 450 on each side. This system offers a total DC capacity of 232 kWp, which is linked to two 110 kW Huawei SUN2000-110KTL-M0 inverters (220 kW AC) and forms a grid-tied PV subsystem that partially offsets the high energy consumption of the hospital. According to the Facility records of the hospital, power consumption is highest in July, which is about 759,000 kWh; this highlights the fact that year-round medical activities in a hot and semi-arid climate are energy intensive. To conduct the study, the actual applied BIPV in the upper part of the windows as bands or belts consists of 753 m\u0026sup2; of glazing, is used as a validated physical reference for glazing type, module transparency, and facade-integration approach. Nevertheless, to assess the performance possibility of transparent BIPV windows on the building scale, the entire facade of the Smart Health Tower is re-created in Rhino and simulated as a complete-BIPV envelope. A precise 3D model of the tower was created with the use of architectural documentations, on-site verified photographs, and geometrical surveying, which led to a total simulated facade area of 5,814 m\u0026sup2;. The facade was subdivided into segments of orientation-dependent surfaces to reflect the fluctuation of the incident solar radiation in the curved geometry of the building. A climate-aligned solar path model for Sulaymaniyah was overlaid onto the reconstructed fa\u0026ccedil;ade to visualize seasonal solar trajectories and calculate their interaction with the building\u0026rsquo;s unique curvature. These climatic and geometric foundations illustrate the dust attenuation modeling, irradiance mapping, and photovoltaic performance simulations explained in the following sections. Therefore, the extended full-fa\u0026ccedil;ade BIPV configuration is a hypothetical design scenario which is developed to investigate maximum feasible energy generation possible under semi-arid environmental conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 BIPV Window Model and Layer Configuration\u003c/h2\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.3.1 Baseline Photovoltaic Glazing Structure\u003c/h2\u003e \u003cp\u003eThe baseline facade model replicates the semi-transparent monocrystalline BIPV glazing typology which is mounted in the current photovoltaic belt in the Smart Health Tower. The actual system comprises 980 semi-transparent monocrystalline modules applied over the two curved sides of the tower (490 modules in each side) giving it a total system DC capacity of 232 kWp on a glazed 753m\u0026sup2; area. This system has two Huawei SUN2000-110KTL-M0 inverters (total 220 kW AC capacity), linked to a grid-tied subsystem that partially meets the electrical needs of the hospital, The applied glazing system includes an exterior glass pane, encapsulating materials, crystalline silicon cell layer, rear encapsulant, and interior structural glass, which does not have a secondary optical or protective layer. This real-world configuration is used as a reference BIPV window system to all the baseline simulations in this research.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.3.2 Semi-Transparent Monocrystalline PV Technologies\u003c/h2\u003e \u003cp\u003eThe modeled BIPV system is characterized by transparency, which is achieved by a spacing-based semi-transparent crystalline silicon configuration with the monocrystalline cells spread out with controlled inter-cell gaps to allow transmission of daylight through. This method parallel with the present BIPV production practice of transparent crystalline modules. The technology applied in the actual installation, which is the high-performance option. The efficiency of the model is Monocrystalline (34% efficiency) This technology concept is an expression of realistic BIPV decision-making, in which energy yields are important in determining the system.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.3.3 Module Dimensions and Full-Fa\u0026ccedil;ade Assignment\u003c/h2\u003e \u003cp\u003eThe actual BIPV belt module is (0.81 \u003cb\u003e\u0026times;\u003c/b\u003e 1.01) m whereas the simulated full facade envelope BIPV module being (3.0 \u003cb\u003e\u0026times;\u003c/b\u003e 1.0) m and (2.0 \u003cb\u003e\u0026times;\u003c/b\u003e 1.5) m to enable full geometrical cover of the recreated 5,814 m\u0026sup2; facade. These module formats are mapped in all the surface areas to maintain constant irradiance analysis and performance analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.3.4 Optical, Thermal, and Electrical Material Properties\u003c/h2\u003e \u003cp\u003eThe assigned material properties such as solar transmittance, visible light transmission, absorptance, thermal conductance and temperature coefficients are done based on manufacturer data and published data of semi-transparent crystalline BIPV systems. Electrical simulations are based on the nature of the current tower subsystems along with a representative DC-AC ratio of 1.05 and the inverter efficiency in line with the Huawei SUN2000-110KTL-M0 units on-site. All the baseline properties are fixed during simulations to facilitate a reasonable comparison between mitigation scenarios.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e \u003ch2\u003e3.3.5 Role of the Secondary Layer in Subsequent Scenarios\u003c/h2\u003e \u003cp\u003eIn the baseline configuration no secondary layer is used. The outer secondary layer representing concentrators, protective films, optical coatings and operational mitigation measures are only presented in the scenario analysis of Section \u003cspan refid=\"Sec23\" class=\"InternalRef\"\u003e3.6\u003c/span\u003e. This keeps the main glazing structures integrity and enables the specific assessment of the dust mitigation measures.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Simulation Tools and Computational Environment\u003c/h2\u003e \u003cp\u003eTo implement the methodological framework, a combination of tools that have been utilized are Geometric modeling, environmental simulation, and photovoltaic performance benchmarking. All the simulations are carried out in a coordinated digital workflow involving Rhino 3D, Grasshopper, Ladybug Tools, and PVsyst, with each software providing a specific analysis function aligned with facade-integrated photovoltaic evaluation. Rhino 3D is the main geometric workspace on which the complete three-dimensional model of the Smart Health Tower is built, its geometry of curved facades, layout of the fenestration and discretized BIPV surfaces. This is a geometric platform that is directly connected to Grasshopper, providing a parametric interface to automate facade segmentation, photovoltaic module assignment, and control material and performance parameters throughout the building envelope. Ladybug Tools are used in the Grasshopper environment to process the local EPW climate file of Sulaymaniyah. By applying radiation analysis components and solar-position algorithms, the program also calculates hourly incident irradiance values per segment of the facade, creating the values explicitly considering the site-specific geometric of the sun, and sky conditions. These are the facade-resolved irradiance outputs which are the main climatic and geometric basis of further performance evaluation and are further modified in Grasshopper to consider dust related attenuation, and temperature dependent effects. PVsyst is featured as an electrical benchmarking and validation instrument, and not the main irradiance modeling engine. The software is utilized to check the baseline electrical yield, performance ratio, and loss structure of BIPV configuration in the facade are in line with industry-standard PV performance modeling. To ensure the baseline system behavior is electrically realistic and comparable to conventional PV performance assessments, the irradiance-informed PV parameters derived from the fa\u0026ccedil;ade-level analysis are linked with PVsyst loss definitions. It is a coherent integrated computational environment that guarantees consistency among geometric representation, climate-based irradiance modeling, and electrical performance benchmarking which forms a strong and clear foundation for measuring the baseline BIPV system and the secondary-layer mitigation scenarios explored in the following sections are.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Secondary Layer Concept and Novelty of the Study\u003c/h2\u003e \u003cp\u003eThis paper proposes an externally mounted glass secondary layer as a facade scale installation to enhance energy production and to improve optical, thermal, and dust-resistance capabilities of transparent BIPV windows in semi-arid climate. Although the current facade of the Smart Health Tower already features a primary semi-transparent BIPV belt without any type of protective or optical enhancement, the approach extends this concept by incorporating a simulated secondary glazing layer to the entire 5,814 m2 building envelope to evaluate the functional possibilities of the building in general. The secondary layer is represented as a free-standing glass sheet arranged outwardly and separated by a ventilated air gap between the BIPV glazing and the secondary glass pane. This design is an effective triple-layer facade system, which has several known architectural and thermal advantages, such as:\u003c/p\u003e \u003cp\u003e(1) minimized the conductive and convective heat transfer across the buffering air cavity;\u003c/p\u003e \u003cp\u003e(2) moderated surface temperatures on the PV layer, thus, reducing the thermal-induced electrical losses;\u003c/p\u003e \u003cp\u003e(3) changed airflow patterns which decrease the adhesion and deposition of airborne dust;\u003c/p\u003e \u003cp\u003e(4) mechanical and UV enveloping that shields the PV glazing against abrasion and long-term degradation; and\u003c/p\u003e \u003cp\u003e(5) enhanced optical management by selectively modifying the outermost layer while keeping the PV assembly unchanged.\u003c/p\u003e \u003cp\u003eEvery dust-reduction measure is done by changing the external layer, such as adding hydrophobic treatment, concentrator film geometry, UV-resistant coating or thermally resilient materials, while keeping the underlying system of BIPV the same. This isolated-variable method guarantees direct comparing between all the six scenarios. The novelty of this study is in transferring the analysis of dust-reduction procedures from isolated module-level interventions to a fa\u0026ccedil;ade-integrated, triple-layer architectural system. No other research has evaluated full-building BIPV functionality under dusty semi-arid environments with an externally mounted protective glazing layer as a versatile platform of several mitigation measures. This fa\u0026ccedil;ade-scale perspective offers a more practical and operational way through which BIPV can be implemented in harsh climatic areas.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Dust Mitigation Scenarios\u003c/h2\u003e \u003cp\u003eThere are six secondary-layer configurations, which were made to test their effectiveness on the optical, thermal, and dust-related performances of the triple-layer BIPV facade system. The core BIPV glazing in any case is not altered, but the outer secondary glass layer, physically separated by an air gap from the core facade, varies to reflect one mitigation strategy at a time. Every scenario is executed by modifying the corresponding optical, thermal or operational parameters in the simulation environment. The scenarios are defined as the following:\u003c/p\u003e \u003cdiv id=\"Sec24\" class=\"Section3\"\u003e \u003ch2\u003e3.6.1 Scenario 1: Optical Film Layer\u003c/h2\u003e \u003cp\u003eAn optical film layer is a coating composed of thin light-management coating layer installed on the exterior of BIPV window to redirect the solar radiation to the photovoltaic surface. It enhances the utilization of diffuse and oblique incident light, helping to maintain effective irradiance under dust-attenuated conditions without changing the window geometry or PV area.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e3.6.2 Scenario 2: Anti-UV / Anti-Scratch Surface Layer\u003c/h2\u003e \u003cp\u003eA durable polymer-based UV-resistant and anti-scratch coating is assigned to the secondary glass layer. The scenario decreases micro-abrasion and surface degradation effects by stabilizing long-term transmittance in the optical model.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003e3.6.3 Scenario 3: Hydrophobic Coating Layer\u003c/h2\u003e \u003cp\u003eA high\u0026ndash;contact-angle hydrophobic treatment is applied to reduce dust adhesion. In the simulation, this is represented by a lower dust-retention coefficient and reduced soiling-loss progression.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section3\"\u003e \u003ch2\u003e3.6.4 Scenario 4: Thermal-Resistant Layer\u003c/h2\u003e \u003cp\u003eA thermally stable external glazing material is introduced to minimize heat absorption and mitigate dust-induced thermal rise in the PV layer. This is achieved by Implementing modified thermal-loss coefficient of the fa\u0026ccedil;ade assembly.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec28\" class=\"Section3\"\u003e \u003ch2\u003e3.6.5 Scenario 5: Modular Operations and Maintenance (O\u0026amp;M) Cleaning Strategy\u003c/h2\u003e \u003cp\u003eThis scenario shows improved operations and maintenance (O\u0026amp;M) cleaning, demonstrated by altering the soiling-accumulation curve of the fa\u0026ccedil;ade. More regular cleaning periods return the transmittance of the external secondary glass layer to baseline levels, minimizing long-term dust buildup. No material changes are introduced; only the cleaning frequency is modified to separate the effect of optimized maintenance on dust-related performance losses.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec29\" class=\"Section3\"\u003e \u003ch2\u003e3.6.6 Scenario 6: Micro Compound Parabolic Concentrator (micro-CPC) Layer\u003c/h2\u003e \u003cp\u003eA micro compound parabolic concentrator (micro-CPC) layer is incorporated within the secondary glazing to geometrically concentrate and redirect incident solar radiation onto the photovoltaic surface. The micro-structured concentrators improve the effective irradiance on the PV layer by capturing light over a wider range of incidence angles without mechanical tracking or additional PV area.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec30\" class=\"Section3\"\u003e \u003ch2\u003e3.6.7 Comparative Evaluation Approach\u003c/h2\u003e \u003cp\u003eAll the mitigation scenarios are checked against the baseline of BIPV facade using the same geometry, climatic inputs, and electrical parameters. The optical, thermal or dust related properties of the external secondary glass layer are only modified in each case. Such controlled configurations ensure any variation in energy yield or performance arising solely from the mitigation mechanisms of being examined and enabling a direct and consistent comparison between all scenarios.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3.1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003elists the material configurations, simulation parameters and functional mechanisms in the six dust-mitigation cases applied on external secondary glass layer.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScenario\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMitigation Type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMaterial\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSimulation Implementation Parameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFunctional Effect / Mechanism\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1. optical Film Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOptical light management\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAngle-selective optical film\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eModified angular transmittance; light-redirection coefficients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRedirects diffuse and obliquely incident radiation toward the PV surface, increasing effective irradiance under dust-attenuated conditions\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2. Anti-UV / Anti-Scratch Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSurface durability\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUV-resistant polymer coating\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStabilized transmittance; reduced degradation factor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMaintains long-term optical clarity; reduces micro-abrasion impacts\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3. Hydrophobic Coating Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSurface dust control\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHigh-contact-angle hydrophobic treatment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLower dust-retention coefficient; reduced soiling-loss rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMinimizes dust adhesion; prolongs clean-surface performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4. Thermal-Resistant Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThermal mitigation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLow-absorptance thermal-stable glass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReduced thermal-loss coefficient; lower PV temperature gain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMitigates temperature-induced electrical losses\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5. Modular O\u0026amp;M Strategy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOperational cleaning\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAdjusted cleaning interval strategy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eModified soiling-accumulation curve; periodic restoration events\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eReduces long-term dust buildup; restores transmittance more frequently\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6. Micro-CPC Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGeometric concentration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMicro compound parabolic concentrator array\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eConcentration ratio; angular acceptance range; irradiance amplification factor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eGeometrically concentrates incident radiation onto the PV layer, increasing effective irradiance without tracking or additional PV area\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec31\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Simulation Setup and Parameterization\u003c/h2\u003e \u003cp\u003eThe baseline and scenario based BIPV facades were assessed on a performance assessment by providing a simulation workflow that incorporated Rhino-Grasshopper, Ladybug Tools and electrical benchmarking with PVsyst. The geometry of the facade, climate data, discretization scheme and electrical layout are all the same across all scenarios to allow a direct comparison of all scenarios. Differences between the scenarios are introduced solely by changing the optical, thermal, or dust-related characteristics of an exterior secondary glazing layer and the primary BIPV system remains unchanged.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec32\" class=\"Section3\"\u003e \u003ch2\u003e3.7.1 Climate and Irradiance Modeling\u003c/h2\u003e \u003cp\u003eHourly climatic information of Sulaymaniyah was imported with regional EPW file and the Ladybug Tools processed in the Grasshopper environment. The Perez sky model was used to calculate the direct, diffuse and global irradiance components and projected onto all the discrete facade elements of the by means of orientation-dependent radiation computations. The angle-of incidence effects were included automatically by the radiation analysis algorithms of Ladybug. The resultant radiation matrices\u0026ndash;stated in annual incident energy per facade element (kWh/m2) produces the primary fa\u0026ccedil;ade-resolved irradiance input for the later performance analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec33\" class=\"Section3\"\u003e \u003ch2\u003e3.7.2 Dust and Soiling Parameterization\u003c/h2\u003e \u003cp\u003eThe amount of dust built-up was modelled by a scenario-dependent soiling-loss formulation over the external secondary glazing layer. The baseline condition implements a standard exponential accumulation profile representing semi-arid deposition trends under periodic maintenance. For example, in Scenario 3 (hydrophobic coating), the dust-retention coefficient is decreased to model lower particulate adhesion while in Scenario 5 (enhanced O\u0026amp;M strategy) the soiling curve is periodically reset to model more frequent facade cleaning. These variations impact only the optical transmittance of the external layer; the main BIPV glazing characteristics essential remain constant across all simulations.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec34\" class=\"Section3\"\u003e \u003ch2\u003e3.7.3 Thermal Modeling Approach\u003c/h2\u003e \u003cp\u003eTo assess the PV operating temperature, the applied method was thermal balance including ambient temperature, incident irradiance, and heat transfer across the facade assembly. The ventilated air gap between the primary BIPV glazing and the external secondary one serves as a moderating cavity that increases the rate of convective heat dissipation and decreases the thermal load on PVs. In Scenario 4 (thermal-resistant layer), the thermal-loss coefficient of the external glazing is changed to reflect materials with lower solar absorptance and stability to thermal conditions. All remaining thermal parameters are kept constant to separate the effect of the secondary-layer intervention.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec35\" class=\"Section3\"\u003e \u003ch2\u003e3.7.4 Electrical Performance Parameters and Benchmarking\u003c/h2\u003e \u003cp\u003eElectrical parameters were harmonized from all the simulations to eliminate the impact of optical, dust-related, and thermal changes. A DC-AC ratio of 1.05 and inverter efficiencies consistent with (Huawei SUN2000-110KTL-M0) units installed in the case study building were applied uniformly. Losses related to mismatch, wiring, temperature coefficients, and light-induced degradation follow the PV dataset associated with the Smart Health Tower system. Performance ratio, electrical yield, and loss distribution for the baseline configuration were benchmarked using PVsyst to prove consistency with industry-standard photovoltaic performance modeling. Electrical parameters were not changed between mitigation scenarios, confirming that observed differences in energy output rise only from fa\u0026ccedil;ade-level optical and thermal effects introduced by the secondary glazing layer.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3.2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eshows Each scenario was implemented by modifying a single dominant physical parameter while keeping all climatic, geometric, and electrical boundary conditions unchanged, allowing direct attribution of performance variation to the proposed secondary layer.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScenario\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePhysical mechanism\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSimulation parameter explicitly modified\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eExact parameter setting in model\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTool level\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline (no layer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReference case\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFront-surface optical properties\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGlass transmittance\u0026thinsp;=\u0026thinsp;reference (e.g., τ₀), reflectance\u0026thinsp;=\u0026thinsp;reference (ρ₀)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRadiation\u0026thinsp;+\u0026thinsp;PV model\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSoiling loss\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFixed baseline soiling loss (e.g., constant loss factor, no mitigation)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModule temperature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStandard temperature model (PVsyst default)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV thermal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1. optical Film Layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReduced dust adhesion and accumulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSoiling loss factor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSoiling loss reduced by fixed percentage relative to baseline (e.g., \u0026minus;X%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOptical transmittance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMaintained at baseline value (no additional optical gain assumed)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRadiation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2. Anti-UV / anti-scratch film\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOptical durability\u0026thinsp;+\u0026thinsp;surface protection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFront-glass transmittance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSlightly increased or stabilized transmittance (τ\u0026thinsp;=\u0026thinsp;τ₀ + Δτ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRadiation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLong-term degradation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDegradation rate set to zero / reduced\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3. Hydrophobic coating\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSelf-cleaning / reduced dust adhesion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSoiling rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLower soiling accumulation rate (slower loss recovery curve)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRain recovery efficiency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncreased cleaning effectiveness (higher recovery fraction after rain)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4. Thermal-resistant layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReduced module operating temperature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOperating cell temperature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCell temperature reduced by fixed ΔT (e.g., \u0026minus;\u0026thinsp;5 to \u0026minus;\u0026thinsp;10\u0026deg;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eThermal\u0026ndash;electrical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTemperature coefficient\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStandard power temperature coefficient retained (e.g., \u0026minus;\u0026thinsp;0.45%/\u0026deg;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV electrical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5. Modular design\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eImproved maintenance and replaceability\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSystem availability\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDowntime losses reduced (availability factor increased)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCleaning frequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncreased cleaning frequency / reduced maintenance interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePV performance\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6. Micro-CPC secondary layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOptical concentration and light redirection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIncident irradiance on PV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEffective irradiance multiplied by concentration factor (C\u0026thinsp;\u0026gt;\u0026thinsp;1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOptical / PV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAcceptance angle losses\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncluded via angular loss modifier (IAM adjusted)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRadiation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOptical losses\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFixed loss terms applied (re-emission, escape, absorption)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOptical model\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModule temperature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTemperature penalty applied due to higher irradiance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eThermal\u0026ndash;electrical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec36\" class=\"Section3\"\u003e \u003ch2\u003e3.7.5 Simulation Workflow and Output Processing\u003c/h2\u003e \u003cp\u003eScenario-specific soiling factors, Fa\u0026ccedil;ade-resolved irradiance matrices, and thermal modifications were processed in the Grasshopper environment to calculate photovoltaic output at facade scale. In every mitigation scenario and module type, the workflow will compute the annual electricity generation, installed PV area and energy yield (kWh/y). Outputs are aggregated for the entire simulated facade area of 5,814.6 m\u0026sup2;, and the current 753 m\u0026sup2; BIPV belt of the Smart Health Tower is applied as a validation reference to assess the performance of the baseline. Comparative performance indicators involve total annual yield, specific yield (kWh/m2), and relative gains compared to the baseline configuration.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec37\" class=\"Section2\"\u003e \u003ch2\u003e3.8 Performance Evaluation Metrics and Comparative Assessment Framework\u003c/h2\u003e \u003cp\u003eTo confirm a systematic and transparent assessment of the mitigation and baseline scenarios, a structured performance assessment framework is implemented. The evaluation emphasizes facade-scale photovoltaic performance and utilizes a series of quantitative indicators that are generally used in the evaluation of building-integrated photovoltaic (BIPV) systems, especially in conditions of variable climatic and operating conditions. The key performance indicators are the annual energy yield (kWh/year) which represents the total electricity being produced at the facade level and the specific energy yield (kWh/m\u0026sup2;\u0026middot;year), which normalizes the production based on the active photovoltaic area and allows normalizes between scenarios with identical geometry. Furthermore, the relative performance gain (%) is computed for each mitigation scenarios relative to the baseline configuration, enabling improvements to be stated independently of absolute yield values. Performance ratio (PR) and trends in the performance of individual performance are mentioned where applicable to help in consistency of interpretation with the conventional practice of assessing photovoltaic performance. Performance ratio (PR) and loss-related trends are referenced where applicable to ensure interpretation is consistent with accepted solar performance evaluation practices. Evaluation of the simulation results uses the baseline-referenced comparison method, while the baseline case corresponds to the existing BIPV fa\u0026ccedil;ade configuration under the same geometric, climatic, and electrical conditions. By normalizing all mitigation scenarios against this validated reference, the framework confirms that any observed performance changes can only be from modifications to the secondary layer properties, such as optical transmittance, dust-related attenuation, or thermal resistance, or concentration effects. Thus, the facade of geometry, climate inputs, discretization strategy, and electrical configuration remained constant for all scenarios to maintain methodological rigor. This controlled-variable approach separates the effect of the secondary-layer interventions and avoids confounding impacts related to system sizing, orientation, or boundary conditions. Therefore, scenario comparisons represent true performance variations due to the proposed mitigation techniques. This comparative framework highlights relative performance trends rather than absolute long-term predictions due to the inherent uncertainties involved in dust accumulation dynamics and thermal behavior of the fa\u0026ccedil;ade. Thus, Mitigation strategies can be ranked according to their effectiveness in improving energy generation at the fa\u0026ccedil;ade level while maintaining the applicability of the results to similar semi-arid, dust-prone settings. The defined evaluation metrics and comparison logic form the methodological basis for the results shown in Section \u003cspan refid=\"Sec39\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec38\" class=\"Section2\"\u003e \u003ch2\u003e3.9 Verification Using the Existing BIPV Facade and cross-tools Benchmarking.\u003c/h2\u003e \u003cp\u003eThe Smart Health Tower contains a built-in BIPV system where the upper part of the window band on every floor function as a photovoltaic glazing element. The current BIPV facade belt is employed as a tool-to-reality verification reference, allowing the validation of facade geometry, distribution of modules, and boundary conditions in the simulation environment. The modeled configuration replicates cumulative facade coverage, as-built PV module dimensions, and vertical placement to consistently match with the applied system. Beyond this built-system verification, another tool-to-tool verification is also done by benchmarking the baseline facade configuration against electrical performance outputs that were created with PVsyst. Key indicators such as performance ratio, annual energy yield, and loss structure are compared at an order-of-magnitude level to confirm that the fa\u0026ccedil;ade-scale simulation results are electrically realistic and consistent with industry-standard photovoltaic performance modeling. Simultaneously, these verification steps provide confidence that the suggested simulation framework is both physically grounded in an existing building application and robust across complementary modeling tools prior to evaluating full-fa\u0026ccedil;ade and secondary-layer mitigation scenarios.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e3.8\u003c/span\u003e \u003cb\u003e(a) (b) (c). Verification of the simulation framework.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e(a) PVsyst baseline performance is used as tool-to-tool electrical benchmarking. (b) PV array and inverter characteristics of the existing BIPV installation used as system reference. (c) Built-system verification of the existing BIPV fa\u0026ccedil;ade belt integrated in the upper window band of the Smart Health Tower, used as tool-to-reality validation.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Results","content":"\u003cdiv id=\"Sec40\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Chapter Overview and Reporting Framework\u003c/h2\u003e \u003cp\u003eThis section reports the simulation results obtained for the Smart Health Tower under the existing BIPV configuration and the proposed fa\u0026ccedil;ade-scale enhancement scenarios. Results are reported using consistent performance indicators to ensure direct comparability across photovoltaic technologies and secondary-layer strategies. The primary indicator is the Annual electricity generation (kWh/year), while specific yield (kWh/m\u0026sup2;\u0026middot;year) is used to normalize performance with respect to active photovoltaic area. For scenario-based assessment within each technology, relative gains are calculated against the full-fa\u0026ccedil;ade, no-secondary-layer reference case. Therefore, the chapter is structured as follows: Section \u003cspan refid=\"Sec41\" class=\"InternalRef\"\u003e4.2\u003c/span\u003e reports the verified baseline performance of the existing BIPV fa\u0026ccedil;ade belt; Section \u003cspan refid=\"Sec42\" class=\"InternalRef\"\u003e4.3\u003c/span\u003e consolidates all monocrystalline fa\u0026ccedil;ade-scale scenarios in a single comparative table; Section 4.4 presents the corresponding polycrystalline scenarios using the same structure; and Section 4.5 provides a concise cross-technology interpretation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec41\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Baseline Results: Existing BIPV Fa\u0026ccedil;ade Belt (As-Built System)\u003c/h2\u003e \u003cp\u003eThe baseline case corresponds to the as-built BIPV system installed on the upper window band of the Smart Health Tower and acts as the verification reference for the following scenario comparisons. Based on the data presented in the building office, the current BIPV belt generates about 321,000 kWh/year of electricity recently. To match the simulation framework with the applied system, the initial configuration of the system was recreated using the Rhino-Grasshopper model with the confirmed facade geometry and module arrangement, consisting of 900 BIPV modules covering an active photovoltaic area of 753 m\u0026sup2;. Under the same baseline configuration, the simulation produces an annual electricity generation of 321,685 kWh/year, indicating close agreement with the reported operational value and supporting the use of the baseline model as a reference for the following scenario-based evaluations.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4.1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline performance of the existing BIPV fa\u0026ccedil;ade belt (verification reference case), comparing reported annual production from the Smart Health Tower building office with the corresponding Rhino\u0026ndash;Grasshopper baseline model output.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAs built (reported by building office)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBaseline model (Rhino\u0026ndash;Grasshopper)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBIPV location\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUpper window band (each floor)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUpper window band (replicated geometry)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of BIPV modules\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e900\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActive PV area (m\u0026sup2;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e752.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e752.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnnual electricity generation (kWh/year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e321,000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e321,685\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecific yield (kWh/m\u0026sup2;\u0026middot;year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e426.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e427.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAgreement (model vs reported)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e+\u0026thinsp;0.21%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec42\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Monocrystalline BIPV Results: Fa\u0026ccedil;ade-Scale and Secondary-Layer Scenarios\u003c/h2\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e4.2\u003c/span\u003e shows monocrystalline BIPV performance results, including the as-built belt configuration used for model verification, the full-fa\u0026ccedil;ade implementation without secondary layers, and a series of independently evaluated secondary-layer and optical enhancement strategies. For comparability among scenarios, the full-fa\u0026ccedil;ade monocrystalline configuration without any secondary layer (gross window area\u0026thinsp;=\u0026thinsp;5,814.6 m\u0026sup2;) is adopted as the reference condition for reporting relative energy gains. Under the full-fa\u0026ccedil;ade, no-layer configuration, the annual electricity generation reaches 2,478,000 kWh/year, reflecting the effect of extending PV-active glazing across the entire fa\u0026ccedil;ade area. The application of individual secondary-layer strategies results in increased improvements in annual energy output relative to this reference case. Optical and surface-based enhancements, including UV/anti-scratch protective layers and anti-reflective (AR) optical films, produce modest gains associated with reduced reflection losses and improved surface durability. Moderate improvements are achieved by system and material level strategies, i.e., modular design of the facade and thermal-resistant coating can generate moderate advancements by moderating electrical mismatch and temperature-related performance losses. The hydrophobic coatings show a greater relative gain, which is in line with the recovery of the losses associated with soiling in dust prone climatic conditions. Maximum energy yield is achieved under the monocrystalline micro-CPC set-up, that generates 4,584,300 kWh/year, equivalent to an 85\u003cb\u003e%\u003c/b\u003e increase relative to the full-facade, no-layer reference. The configuration is a radically new optical collection concept and therefore seen as a system-level improvement and not a traditional secondary-layer optimization.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4.2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eis a summary of the monocrystalline BIPV performance. The entire face configuration with no secondary-layers is used as the reference case and effects of each secondary-layer or micro-CPC added in isolation are measured separately relative to this baseline.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScenario\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePV area (m\u0026sup2;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModules\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAnnual energy (kWh/y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSpecific yield (kWh/m\u0026sup2;\u0026middot;y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eΔE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSecondary layer / Strategy\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline (no secondary layer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,478,000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e426.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNone\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1. Optical film layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,552,340\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e439.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e3.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eOptical enhancement film (Anti-Reflective transmittance control)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2. Anti-UV / anti-scratch film\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,621,724\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e450.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e5.8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eProtective anti-UV / anti-scratch film\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3. Modular design\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,651,460\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e456.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e7.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eModular fa\u0026ccedil;ade layout / electrical segmentation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4. Thermal-resistant layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,725,800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e468.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e10.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eThermal-resistant / spectrally selective layer\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5. Hydrophobic coating\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,800,140\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e481.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e13.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHydrophobic coating (soiling mitigation)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6. Micro-CPC configuration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4,584,300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e788.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e85.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMicro-CPC secondary optical concentrator\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec43\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Polycrystalline BIPV Results: Rationale and Key Performance Indicators\u003c/h2\u003e \u003cp\u003eBesides monocrystalline systems, polycrystalline BIPV systems were also modeled to reflect cost-sensitive fa\u0026ccedil;ade-scale applications. Due to the low cost of production, polycrystalline modules are still credible when the economic considerations affect the choice of technology. In the full-fa\u0026ccedil;ade set-up without secondary layers (gross window area\u0026thinsp;=\u0026thinsp;5,814.6 m2), the polycrystalline system yields 1,457,647 kWh/year which is taken as the reference point. The lower production compared with the monocrystalline scenario can be mainly explained by the lower conversion efficiency of polycrystalline modules (20% versus 34%), but it still sets a realistic benchmark to make a comparative evaluation. Secondary-layer and system-level approaches generate incremental advancements in yearly energy production compared to this baseline. UV/anti-scratch layers, optical films, thermal-resistant layers, modular facade design, and hydrophobic coating will result in moderate improvement by reducing reflection losses, thermal degradation, electrical mismatch, and soiling features in dust-prone climatic conditions. Optimal polycrystalline energy production is obtained in the micro-CPC setup, which is equal to 2,696,647 kWh/year which is equivalent to 85 percent higher compared to the full-facade no-layer reference. Like monocrystalline, this configuration is an optical improvement on the system level rather than conventional secondary-layer optimization. By using the same facade geometry, environmental condition, and scenario definitions, the research makes it possible to directly and consistently compare monocrystalline and polycrystalline BIPV technologies to make informed design decisions in different cost-performance priorities.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4.3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePolycrystalline BIPV facade-scale results in the baseline case, secondary-layer and micro-CPC with relative gains to the full-facade no-layer case.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScenario\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePV area (m\u0026sup2;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModules\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAnnual energy (kWh/y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSpecific yield (kWh/m\u0026sup2;\u0026middot;y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGain vs full-fa\u0026ccedil;ade no-layer (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSecondary layer / Strategy\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline (no secondary layer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,457,647\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e250.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNone\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1. Optical film layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,501,376\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e258.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eOptical enhancement film (AR / transmittance control)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2. Anti-UV / anti-scratch film\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,542,191\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e265.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eProtective anti-UV / anti-scratch film\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3. Modular design\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,559,682\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e268.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eModular fa\u0026ccedil;ade layout / electrical segmentation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4. Thermal-resistant layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,603,412\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e275.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eThermal-resistant / spectrally selective layer\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5. Hydrophobic coating\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,647,141\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e283.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHydrophobic coating (soiling mitigation)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6. Micro-CPC configuration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,814.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,696,647\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e463.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e85.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMicro-CPC secondary optical concentrator\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"5. Discussion","content":"\u003cp\u003eThe findings verify that efficiency of BIPV windows across semi-arid and dust-prone climates are intensely affected by fa\u0026ccedil;ade-level optical, thermal, and soiling-related aspects. The recalculated absolute energy outputs emphasize the necessity of system-level assumptions, facade coverage, and secondary layer integration in evaluating the actual impact of window-integrated photovoltaic on building energy demand. When operating under the no-secondary-layer full-facade with a monocrystalline BIPV system, the system generates 2.48 GWh/year, whereas the polycrystalline system generates 1.46 GWh/year. Such differences are a result of the greater intrinsic conversion efficiency of monocrystalline technology at identical geometric and climatic conditions. Regardless of this certain gap, the two technologies demonstrate very stable relative reactions to the interventions of secondary layers, which means that the observed improvement in performance is largely determined by facade-level environmental interactions and not only by cell technology alone. Relative energy gains of both secondary-layer technologies range from +\u0026thinsp;3% to +\u0026thinsp;13%. Optical Film improvements and anti-UV/anti-scratch layers give modest improvements by stabilizing the surface transmittance and reducing optical degradation. Modular facade design can provide intermediate gains by enhancing system availability and electrical segmentation, whereas thermal-resistant layers are able to provide even greater benefits by decreasing temperature-driven efficiency losses caused by high irradiance and dust-enhanced surface heating. Hydrophobic coating is one of the non-concentrating strategies that provide the highest incremental gains, which highlights the importance of soil reduction in the environment with low rainfall and high persistent airborne dusts. The practical value of these findings is understood better when BIPV electricity generation is associated with the operational energy demand of the Smart Health Tower. Building documents show that electricity use reaches about 759,000 kWh in July, showing the peak demand period mainly due to cooling loads. Using a simple average-month estimation, the baseline monocrystalline BIPV setup (2,478,000 kWh/year) will provide approximately 206,500 kWh in July, which will supply about 27\u003cb\u003e%\u003c/b\u003e of the towers\u0026rsquo; July power demands. In the case of the hydrophobic coatings, the estimated production in July is 233,300 kWh which serves about 31% of the July demand. At the micro-CPC setting, estimated July production is 382,000 kWh which is equivalent to about 50% of the July electricity demand. In the case of the polycrystalline system, the baseline system will provide about 16% of July demand, which rises to 18\u003cb\u003e%\u003c/b\u003e when using hydrophobic coating and reaching about 30% under the micro-CPC configuration. Although these estimates do not account for hourly or monthly variations, they show that facade-integrated BIPV windows may serve as a significant share of peak-period electricity demand in large health facilities, especially when more sophisticated strategies of secondary-layer or optical concentration are used. The micro-CPC configuration is a type of intervention which is fundamentally different from the surface-based secondary layers. By adjusting the optical collection mechanism and concentrating incident radiation to the photovoltaic elements, micro-CPC systems generate a step-change in energy production (around +\u0026thinsp;85%) for both technologies. Therefore, they must be understood as facade-integrated optical systems rather than incremental dust-reduction measures, preserving an easy separation between facade optimization and system-level redesign. In general, the findings confirm the primary premise of this research: that meaningful enhancements of BIPV window performances can be enhanced significantly using facade-integrated secondary layers, which address optical, thermal, and soiling-related losses in dust-prone regions. Incremental strategies offer robust and scalable improvements whereas system-level optical concentration is much more promising in terms of offsetting building electricity demand but carries additional design costs. Collectively, these results offer an organized framework for choosing BIPV window advancement techniques according to performance aims, environmental conditions, and design priorities in large-scale building applications.\u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eThe present study explored the facade-scale performance of building-integrated photovoltaic (BIPV) windows when based in semi-arid, dust-prone environments, and especially including the role of secondary-layer strategies in reducing optical, thermal and soiling-related losses. By employing the Smart Health Tower as the real-world case study, a simulation-based model was used to compare monocrystalline and polycrystalline BIPV window efficiency in same geometric and climatic environment. The findings indicate that facade integrated secondary layers offer significant and reliable enhancements in BIPV window performance. In both technologies, incremental strategies achieve relative annual energy gains of up to \u0026asymp;\u0026thinsp;13%, with hydrophobic coatings indicating the strongest impact among non-concentrating solutions. Thermal resistant layers also improve performance by eliminating efficiency losses due to temperature, whereas optical films, protective layers and modular facade configurations contribute to more reasonable but robust improvements that support long-term operational stability. The entire-facade monocrystalline BIPV system will produce an annual electricity production of \u0026asymp;\u0026thinsp;2.48 GWh compared to \u0026asymp;\u0026thinsp;1.46 GWh with the polycrystalline configuration. Despite this discrepancy, both technologies show equivalent proportional response to secondary-layer interventions, demonstrating that the efficacy of performance enhancement strategy is controlled mainly by fa\u0026ccedil;ade-level environmental interaction instead of photovoltaic cell type. This proves the technical feasibility of polycrystalline BIPV windows for cost sensitivity on the facade applications when paired with suitable secondary layers. In terms of building operation, the baseline monocrystalline BIPV facade provides about 27% of the Smart Health Tower\u0026rsquo;s July electricity demand (\u0026asymp;\u0026thinsp;759,000 kWh), with hydrophobic layer rising to 31%, and reaching\u0026thinsp;\u0026asymp;\u0026thinsp;50% with the micro-CPC setup, the percentage rises to 50 per cent based on an average-month approximation. The values show that optimized BIPV windows are practically capable of offsetting a significant portion of electricity consumption in large healthcare facilities during the peak period. The micro-CPC system results in a step-change increase in yielding energy about\u0026thinsp;+\u0026thinsp;85%, which is a system level optical intervention rather than an increase in surface treatment. This strategy has much greater performance potential but also brings greater design complexity which must be addressed at the architectural and facade-integration level. Overall, the results prove that secondary layers are not an auxiliary addition but an essential element of efficient BIPV windows in dust prone areas. To address environmental degradation mechanisms, facade-integrated secondary layers allow BIPV windows to achieve reliable, scalable, and context- responsive performance, enhancing their role as a meaningful contributor within the building energy systems rather than a purely architectural feature.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions Statement\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eI.S. designed and created this research, established the methodology, carried out the simulations and analysis, and written the original manuscript and S.Y.B. supervised the research, offered conceptual guidance throughout the research, and assisted with the critical revision of the manuscript. Both authors revised and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional Information:\u003c/strong\u003e\u003cbr\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e The authors received no specific funding for this work.\u003c/p\u003e\n\u003cp\u003eData availability: The findings of this study are supported by data extracted from published literature and the simulation results generated by the authors using Rhino, Grasshopper, Ladybug, and PV-syst workflows, and climate input data were obtained from publicly available sources (EPW weather files) and associated performance tools. The corresponding author will provide derived datasets and key simulation outputs upon reasonable request.\u003c/p\u003e"},{"header":"References ","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMangherini, G., Diolaiti, V., Bernardoni, P., Andreoli, A. \u0026amp; Vincenzi, D. 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Building Eng.\u003c/em\u003e \u003cb\u003e102\u003c/b\u003e, 111940. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jobe.2025.111940\u003c/span\u003e\u003cspan address=\"10.1016/j.jobe.2025.111940\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Building-integrated photovoltaics (BIPV), Dust mitigation, optical concentrators, Multifunctional facade systems, Semi-arid climates","lastPublishedDoi":"10.21203/rs.3.rs-8807699/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8807699/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe problem of dust continues to be a constant performance barrier to building integrated photovoltaic (BIPV) windows. This paper has innovated the field since the secondary-layer concept is proposed to consist of dust-reduction films, thermo-resistant materials, and optical redirection elements that work together as a multifunctional enhancement system. where most recent research assesses protective layers and optical concentrators as separate strategies. Through a full-scale application of the Smart Health Tower in Sulaymaniyah, a workflow created in Rhino, Grasshopper, Ladybug and PV-syst was executed to recalibrate the performance metrics of existing monocrystalline BIPV glazing. The baseline model established an annual energy yield of 321,685 kWh, applied only in upper part of the windows, serving as the benchmark and validation for evaluating the proposed scenarios. The analysis demonstrates that consolidating UV stabilization, thermal regulation, and micro-optical concentration within a protective layer significantly mitigates environmental degradation while enhancing energy production, loss prevention due to soiling, and long-term facade stability. This paper presents a novel strategy for next-generation BIPV window in dusty and high-irradiance environments by demonstrating the synergy gains achieved on merging protective and optical capabilities.\u003c/p\u003e","manuscriptTitle":"Optimizing BIPV Windows in Dust-Prone Regions: Enhanced Strategies for Energy Efficiency in Semi-Arid Climates","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-16 23:48:41","doi":"10.21203/rs.3.rs-8807699/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-05T19:40:54+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-05T06:16:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245239793338593707693814652308770579678","date":"2026-03-04T07:48:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245642599863166993796933086600097857273","date":"2026-03-04T07:12:07+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-26T22:09:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"18057137929376185640271894833163060016","date":"2026-02-18T17:19:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154120919247405549406553543240042873032","date":"2026-02-13T15:37:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"115700840449144041661321950230733773127","date":"2026-02-11T18:14:47+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-11T17:14:07+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-10T18:45:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-09T14:35:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-09T14:31:01+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-02-06T13:05:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1f85f6c1-d6fa-4272-aef3-9ae61db8dba6","owner":[],"postedDate":"February 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":62896419,"name":"Physical sciences/Energy science and technology"},{"id":62896420,"name":"Physical sciences/Engineering"},{"id":62896421,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2026-05-12T07:42:31+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-16 23:48:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8807699","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8807699","identity":"rs-8807699","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}