Selecting Building Façade Materials by Integrating Stepwise Weight Assessment Ratio Analysis and Weighted Aggregated Sum Product Assessment into Value Engineering

Abstract

Building façades represent one of the most critical elements affecting a city’s quality of life, and they impact the country’s economic income by attracting visitors. However, performance data on façades are limited or incomplete, making it challenging for designers to evaluate their effectiveness in energy efficiency, thermal performance, durability, and other key performance metrics. This paper presents a comprehensive framework for evaluating and prioritizing material selection criteria in building cladding, establishing the relationship with available alternatives, and integrating decision-making processes with Building Information Modeling (BIM) to automate the Value Engineering (VE) concept. The material selection criteria from the literature and international standard manual were identified, and their criteria weight was then evaluated using SWARA (stepwise weight assessment ratio analysis). Additionally, WASPAS (weighted aggregated sum product assessment) was utilized to evaluate the alternative cladding materials based on the defined criteria and their associated quality weight (QW). The life cycle cost (LCC) of the alternatives was computed. The VE was computed and then ranked based on the QW and LCC of the alternatives. The procedure was connected to the BIM model to automate the assessment, specifying the necessary parameters and the BIM computation. A case study of an office building façade was conducted to validate the proposed framework. In this study, the significant criteria were durability, wind load resistance, and thermal insulation. This approach enables executives to evaluate cladding selection, ensuring efficient decision-making processes. The proposed method and its results were subjected to expert testing, and the satisfaction rate exceeded 80%, confirming the framework’s reliability in evaluating alternatives. This paper enhances the understanding of material selection methodologies and provides a valuable contribution to the field of construction management.

1. Introduction

The building envelope is one of the most important exterior elements for building performance. The façade is an elegant component that helps to define the unique aesthetics of a building, reflecting modern architecture or cultural heritage. It also has a critical role related to the sustainability and performance of a building; as technology advances, various advancement options become available for incorporation into building façades. These elements are geared toward the improvement of the building envelope performance. Keeping in mind technological advancement and increased flexibility in selecting materials from various options, preserving cultural heritage is also very important. This involves using materials that retain the original character of the building façade. A substantial portion of the construction project cost depends on building materials. The specified materials and recommended construction items significantly affect the project’s cost [1]. Moreover, a survey of home builders conducted by the National Association of Home Builders [2] reported that building envelopes comprise 7.2% of the total construction cost [3].

On the other hand, the combination of the performance requirements of the building and cultural importance of the area plays a vital role in selecting appropriate façade materials. For example, the Royal Commission for the City of Riyadh transformed the historic neighborhoods of Diriyah into a cultural capital. The Qasr Al-Hukm neighborhood development project represents an outstanding success in revealing the characteristics of the past in a modern way. Some buildings have been partially renovated, with their façades repaired while preserving the Salman architectural character of the area. After renovation, the architectural elements were either used for cultural activities or preserved as relics in their original form for museum display. Completely renovated and restored buildings and places are open to visitors, such as Diriyah Park, Imam Saud Mosque, Salwa Palace, Al-Masmak, Al-Thumairi Gate, and Al-Safah Plaza [4].

A city’s quality of life can significantly impact the number of visitors the country receives. A high quality of life can increase a city’s attractiveness as a tourist destination, increasing visitor numbers [5]. Aesthetics and cultural appeal are two critical factors influencing a city’s quality of life. Cities with a high quality of life frequently have appealing and culturally vibrant environments [6]. Beautiful architecture, well-maintained public spaces, and a rich cultural heritage can enhance a city’s attractiveness to tourists. Cities that offer unique experiences, such as historical landmarks, museums, art galleries, festivals, and other cultural attractions, attract visitors. Other factors aside from aesthetics and cultural appeal include safety and security, infrastructure and accessibility, hospitality and services, environmental sustainability, and livability. While the quality of life in a city can attract visitors, other factors such as marketing efforts, natural attractions, historical significance, and a country’s overall tourism infrastructure all play a role in attracting visitors. A comprehensive approach considering a city’s quality of life and other tourism-related factors can contribute to a brisk increase in visitor numbers.

Real-world issues are typically too complex to evaluate a single criterion, quality, or point of view that will result in the best choice. Accurate decision-making involves considering several competing criteria and goals at once. The selection of materials in the early phase of a project depends on many factors, such as numerous technical, environmental, and economic factors and the involvement of several stakeholders [7]. Value Engineering (VE) involves the systematic utilization of established methods to determine the system’s performance at the most economical cost possible. The selection process of façade materials for different kinds of buildings requires the assessment of quantitative and qualitative criteria, making the process a challenging task. Quality must be evaluated and scored; therefore, the criteria must be defined, and weights must be considered. Based on the concept of Value Engineering (VE), making more viable and valuable choices entails considering the clients’ preferences in the decision-making process to attain optimal function with the highest quality while minimizing costs. Dell’Isola and Dell’Isola [8] developed the value ratio formula, as shown in Equation (1).

VE = (Performance + Quality)/Cost

(1)

where Performance + Quality refers to the primary purpose or desired outcome of the alternative and Cost involves the assessment of various costs associated with the system, including initial acquisition costs, operational costs, maintenance costs, and life cycle costs. Further details on the method are outlined in Section 2.3 and Section 3.6. Previous studies have successfully developed a comprehensive model combining Building Information Modeling (BIM) with material evaluation to streamline the process [9]. However, a significant gap exists in the literature where many of these studies have failed to isolate the cost criteria within the evaluation process. In addition, there is a need to incorporate new multi-criteria decision-making (MCDM) techniques to identify value-driven alternatives for building façade materials. By integrating these techniques into the research framework, a more robust and comprehensive decision-making process can be established. Moreover, the literature lacks a comprehensive framework combining BIM, material evaluation, and cost criteria in building façade material selection.

This study aims to bridge this gap by developing a framework that considers the quality, cost, and stakeholder preferences to enable informed decision-making in building façade materials. Therefore, the SWARA approach was used for weighing and evaluating criteria. It is a lot easier to use than other MCDM tools. So far, the SWARA approach has been applied in various fields. The SWARA approach was adopted to calculate the weights of the evaluation criteria, while the WASPAS method was used to calculate the quality weight of the alternatives. Then, the normalized life cycle cost was computed. Following this, the VE of the alternative façade material was determined based on the LCC and quality criteria. Users can apply the relative weight of ranking selection criteria according to the material performance of the building in the BIM framework model. If building materials are automated in this way, VE can be used more efficiently. To validate the framework, a case study of a building will be worked upon, and building façade elements will be evaluated. Our hope is that this research can offer practical value to design engineers engaged in the process of selecting alternative façade materials. However, this is challenging and usually not adequately studied due to the lack of systematic and scientific evaluation methods for the quality performance of materials.

2. Literature Review

This section provides a comprehensive review of the literature on building façades and material evaluation criteria. Furthermore, in this section, VE is introduced, and the reasons for choosing SWARA and WASPAS methods among different MCDM tools to adapt this research are discussed. An overview of Building Information Modeling (BIM) is also provided, highlighting its significant benefits and relevance to the research topic.

2.1. Building Façades

Building façades play a vital role in their overall performance and aesthetics, encompassing both performance and architectural aspects. Over the past few years, several significant research studies have shed light on various aspects of building façades [10,11]. These studies have explored advancements in façade materials, energy-efficient façade design, sustainability considerations, and innovative technologies for improving façade performance.

Tian et al. [12] investigated using novel materials and technologies for energy-efficient building façades. The researchers explored integrating phase change materials (PCMs) within the façade system to enhance thermal performance and reduce energy consumption. In their study, a manual façade system and an intelligent façade system were compared, with the results indicating that the innovative façade system would perform better.

Sustainability considerations also represent a critical area of research on building façades. The integration of renewable energy technologies within building façades has gained significant attention. A study by Balali et al. [13] explored the potential of incorporating photovoltaic panels into façade systems to generate electricity. Regarding the environmental issues, Wang et al. [14] investigated the environmental impact of different façade materials and construction techniques. Their study evaluated the life cycle assessment (LCA) of façade systems and compared the environmental performance of glass, aluminum, and composite panels. They stated that assessing insulated external walls is essential for cutting building energy use and greenhouse gas emissions, especially in areas with extreme weather. For example, in regions with hot climates, insulated external walls are vital for minimizing heat gain from the external environment. Effective insulation can prevent excessive heat transfer into the building, reducing the need for extensive air conditioning and cooling systems. Reducing the demand for cooling decreases energy consumption, leading to lower greenhouse gas emissions from power generation.

Building façades in the Middle East, particularly in the Kingdom of Saudi Arabia (KSA), present unique challenges and considerations due to the region’s specific climatic conditions and cultural preferences. In a study by Aldossary [15], the authors investigated the impact of intense solar radiation and high ambient temperatures in the KSA on the performance of building façades. Energy-saving glass, renewable energy methods, and shading strategies were some of the suggested ways to cut down on energy use. By utilizing IES-VE to evaluate each home’s renovation, these methods were shown to reduce energy consumption by up to 37%, contingent upon local meteorological conditions [15]. Al-Najm [16] and Bay et al. [17] delved into the incorporation of the Najdi theme into building façades in KSA, including the use of gypsum ornaments, traditional windows (Rawasheen), and decorative wooden screens (Mashrabiya) to establish a visual connection with the local culture and enhance the aesthetic appeal of buildings in Riyadh, specifically in Ad Diriyah. Alzahrani [18] focused on the cultural aspects influencing façade design. The research highlighted the significance of preserving cultural identity in façade design while incorporating modern technologies and materials to meet the population’s evolving needs. Khalifeeh et al. [19] explored integrating renewable energy technologies, specifically solar panels, within building façades in the KSA. Al-Najm [16] examined the significance of cultural storytelling through façades in Riyadh. The research emphasized the role of façades as a medium to convey cultural narratives, history, and values. The authors discussed using symbolic representations, calligraphy, and visual storytelling techniques in façade design to foster a sense of identity, pride, and connection to the local community.

These recent research studies highlight the ongoing advancements and considerations in building façade design and technology [20,21,22]. In the regional context, research studies demonstrate the growing focus on developing context-specific façade solutions in the KSA. Integrating energy-efficient design strategies, considering cultural elements, and exploring renewable energy technologies are all critical factors in creating sustainable and culturally appropriate building façades in the region.

Table A2. SASO standards for building cladding materials [81].

No.	Category	Product
1	Gypsum board	Composite gypsum boards
		Gypsum board cornices
		Insulating panels
		Synthetic rock wool
2	Polystyrene	Rigid polyurethane, Polystyrene
		Polyurethane foam
		Rigid polyurethane panels/isochrons
		Rigid polyurethane/isocyanurate plates
		Rigid polyurethane/isocyanurate plates
		Polyurethane/isocyanurate plates
		Rigid polyurethane/isocyanurate plates
		Rigid polyurethane/isocyanurate plates
3	Metal and aluminum panels	Metal panels for interior ceilings and walls
		Metal panels reinforced for external cladding
		Aluminum composite panels for exterior cladding
4	High-Pressure Laminate panels	HPL P = panels
		HPL cladding
		HPL façade panels
		HPL exterior cladding
5	Wood panels	Engineered wood panels
		Parquet boards
		Wood composite panels
		Solid wood cladding
6	Natural stone panels	Granite panels
		Limestone panels
		Marble panels
7	Cement fiber panels	Fiberboard
		Fiber-reinforced polymer (FRP) panels
8	Coated Building Glass	Coated building glass
9	Artificial stone panels	Solid surface
		Cultured marble
		Terrazzo
		Precast concrete panels

, as shown in Appendix A, displays the standards in the KSA set by the Saudi Standards, Metrology and Quality Organization (SASO) for building façade materials. These guidelines aim to ensure the quality, safety, and performance of façades whilst adhering to local regulations and standards. The guidelines cover various aspects of façade design, construction, and maintenance.

This literature review reveals several knowledge gaps regarding the research topic of developing a comprehensive framework for the selection of building façade materials. Specifically, there is a lack of emphasis on cost criteria within the evaluation process, which has not been adequately addressed, as well as a lack of integration of new MCDM techniques in the selection process of building façade materials. There is a gap in the literature regarding the explicit consideration of stakeholder preferences. Stakeholders, such as architects, clients, and subcontractors, often have specific requirements and preferences that must be considered during the material selection process. There is a notable absence of an automated model designed to select building façade materials within the BIM framework.

2.2. Material Selection Criteria

Building materials play a vital role throughout the life cycle of a building. The selection of materials for constructing the building is one of the most critical design decisions in the early phase. Typically, several solutions are considered to select the best building design alternatives. These solutions should be optimally evaluated from the perspective of several quantitative and qualitative criteria [23].

Some researchers have limited themselves to evaluating the alternative materials according to the cost and environmental criteria [24,25,26]. Other studies have focused on evaluating the energy versus cost criterion in comparing alternatives [27]. In addition to the cost, environmental impact, and energy efficiency, researchers also consider other criteria, such as quality. Evaluating alternative materials based on multiple criteria helps ensure that the chosen materials meet the desired standards and contribute to the overall performance and durability of the building.

In summary, material evaluation criteria encompass various factors such as the cost, environmental impact, energy efficiency, durability, and maintainability. The literature on these criteria is listed in

Table 1. Literature review for selection criteria.

No.	Façade Material Selection Criteria	References
1	Durability and maintainability	[28,29,30,31,32]
2	Buildability	[33,34,35]
3	Sustainability	[33,36]
4	Health and safety	[37,38]
5	Cultural heritage and aesthetics	[16,17]
6	Visual comfort	[39,40,41]
7	Daylighting performance	[39,42,43]
8	Fire resistance	[44,45]
9	Thermal performance	[12,14,23,46,47,48,49]
10	Acoustic performance	[23,45,47,50,51]

. Researchers continue to explore innovative approaches and methodologies to optimize the selection process and ensure that materials meet the desired criteria for sustainable and efficient building construction.

2.3. Value Engineering (VE)

VE in the construction industry is primarily an organized attempt to challenge the design to provide the required facility at the lowest total costs, consistent with requirements for performance, reliability, and maintainability [52]. According to the Society of American Value Engineers (SAVE), VE is “a systematic application of recognized techniques that identify the performance of a system at the lowest overall cost.” VE attracts significant attention as a new way to reduce costs and increase profitability. Its methodology was developed in the 1940s. It was discovered that performance-oriented alterations in working methods often improve quality and eliminate unnecessary costs.

Recent research in VE has focused on developing advanced techniques and methodologies to improve its application in the construction industry. For example, one study [53] provides an in-depth analysis of engineering practices’ value and impact on project outcomes. This research highlights the importance of VE in cost reduction and improving project efficiency.

Table A3. Literature review of MDCM techniques for the selection process.

Technique	Objective	Reference(s)
Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)	Selecting machine learning models	[54]
Best Worst Method (BWM)	Textile industry	[55]
Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE)	Green construction	[56]
Superiority and Inferiority Ranking (SIR)	Ranking alternatives based on multiple criteria decision-making	[57]
Stepwise Weight Assessment Ratio Analysis (SWARA)	Ranking alternatives based on multiple criteria	[58]
Weighted Aggregated Sum Product Assessment (WASPAS)	Green supplier	[59]
SWARA, WASPAS, and VE	Construction foundation type	[60]

shows many areas of research in VE [54,55,56,57,58,59,60].

2.4. SWARA and WASPAS

Keršuliene et al. [61] developed a new MCDM method called Stepwise Weight Assessment Ratio Analysis (SWARA). SWARA’s approach differs from those of other related methodologies, such as pairwise comparison and FARE. Experts play a crucial role in assessing and determining weights using this method. The central feature of this method is the capacity to estimate experts’ opinions on the critical ratio of the criteria. SWARA is a tool for determining the importance and relative weights of criteria. SWARA uses a pairwise comparison technique to establish the relative importance or weights of criteria. On the other hand, fuzzy logic approaches the determination of criteria weights by considering the ambiguous and uncertain nature of the decision-making procedure.

The weighted aggregated sum product assessment (WASPAS) approach is used to solve MCDM problems, thus improving ranking accuracy, and it can achieve the maximum estimation accuracy [62,63]. This strategy includes a defense against the considered alternatives’ rank reversal. This approach is also proven to have the unique capacity to solve both single- and multi-response optimization problems.

Beneficial and non-beneficial criteria are evaluated evenly in WASPAS; however, they are normalized individually. Rather than considering all performance values, the WASPAS method uses a normalization strategy that considers only two performance values, i.e., the minimum (for non-benefit qualities) and maximum (for advantageous attributes). As a result, the normalized scores derived using this method are inaccurate [64].

Table A3 (as shown in Appendix A) shows the application of MCDM methods in different fields. Several studies have dealt with building construction; for example, Ranjbar et al. [65] performed SWARA to prioritize energy consumption optimization strategies in buildings in Iran, while it was used in Sri Lanka to assess the impact of integrating disaster resilience indicators into a Green Building Rating System [66]. A few studies combined SWARA and WASPAS into the VE method. This technique was applied in the selection of façade material in this study.

2.5. Building Information Modeling (BIM)

To automate the evaluation of building materials, a wide range of data need to be collected and analyzed, such as material specifications, prices, and quantities. BIM is adapted to facilitate and automate the process. Researchers have examined the concept of BIM for the last few decades, together with the emergence of computer-aided design (CAD) tools. Nevertheless, over this period, the extent of the concept was a three-dimensional building model enriched with some additional graphical information [67]. The broad scope of BIM usage incorporates data management from the initial design and throughout a building’s life cycle [68]. BIM tools also grant a proper platform for implementing additional features for performance assessment into a building model [69].

Table A4. Literature Review on Building Information Modeling.

No.	Objectives	Research Methodology and Findings	References
1	To develop a BIM-based material selection framework.	Indoor environmental quality (IEQ)	[70]
2	To reduce waste and carbon emissions through BIM-based LCA.	Assessment of carbon emissions of timber structures	[71]
3	To integrate energy optimization proposals for building surfaces using new materials and design options.	Village building	[72]
4	To identify the most influential parameters in the energy consumption of high-rise buildings.	High-rise residential building	[92]
5	To identify the effects of buildings’ geometry on the energy consumption of high-rise buildings in seven Egyptian cities.	High-rise building energy consumption	[73]
6	To optimize features of windows, e.g., glazing, opaque materials, and shading elements of high-rise buildings.	High-rise building	[74]
7	To test the efficacy of DSF external walls for energy savings in a high-rise building located in a Mediterranean climate.	High-rise building energy consumption	[75]
8	To optimize the thermal performance of high-rise buildings using a DSF system.	High-rise building energy consumption	[76]
9	To analyze the request for information process during the planning stage of high-rise buildings.	High-rise building planning management	[77]
10	To improve decision-making processes, enabling green materials to be selected for high-rise buildings.	Green material	[78]

(as shown in Appendix A) shows the recent work performed in BIM, especially in buildings [70,71,72,73,74,75,76,77,78].

3. Methodology

Methodology is crucial in achieving research objectives by systematically gathering and analyzing data. This study’s methodology focuses on cladding material selection for office buildings. The framework utilized in this study mainly consists of seven sequence steps, as displayed in Figure 1. The first step represents all collection criteria by reviewing the previous studies and books, international material standards, and several international quality standards. Then, the suitable criteria for the Saudi market were identified and selected using semi-structured interviews with Saudi construction experts. After that, the weight of the selected criteria was determined using the SWARA method. The quality weight (QW) of the common cladding materials was assessed using the WASPAS method. Then, the LCC of the common cladding materials was evaluated. Finally, the value scoring was used to determine the most valuable alternative material. Defining these inputs ensures a comprehensive evaluation of materials. Then, it can be integrated with Building Information Modeling (BIM). This integration allows decision-makers to observe the effects of their material choices in real-time and automate the evaluation process.

3.1. Collect Data

This step involves identifying the factors (criteria) essential for material selection for building façades. Firstly, criteria for the selected materials are determined through various methods such as the examination of literature reviews studying international material standards. Several international quality standards are used to evaluate the material’s required quality (ISO, SASO, ASTM, and EN), which also prove useful when measuring quality criteria via proposed tests, interviews with experts, the development of a questionnaire, and surveying the construction market.

The evaluation criteria include quality standards, aesthetic standards, maintainability, buildability, and cultural heritage. These are used to determine the cladding finishing materials that are widespread in the local market and compatible with the building performance, differing in their applications. According to the code of practice on buildability [79], the building categories are classified as shown in

Table A5. Building Categories.

Categories	Types of Development
Residential (landed)	Terrace house
	Semi-detached house
	Bungalow
	Clustered housing
Residential (non-landed)	Condominium
	Flat
	Service apartment
	Apartment
	Dormitory
	Hostel
Commercial	Bank
	Departmental store
	Shopping center
	Office building
	Supermarket
	Restaurant
	Hotel
	Conventional hall and facilities
	Exhibition hall
Industrial	Factory
	Warehouse
	Godown
	Brewery
	Cold storage building
	Packaging and processing plant
	Printing plant
School	Primary school
	Secondary school
Institutional and others	Library
	Hospital
	Home for the aged
	Childcare center/nursery
	Research building
	Educational facility
	Terminal building
	Campus
	Medical center
	Camp
	Embassy
	Museum
	Crematorium and columbarium
	Clubhouse
	Cinema/theatre
	Sports/recreational facilities
	Public transport station
	Sub-station

(as shown in Appendix A).

3.2. Identify and Select Criteria

Some of the most common cladding types used in construction projects in the KSA include aluminum cladding, ceramic, and natural stones such as Riyadh stone, marble, and granite. Gathered technical specifications for cladding proposed by SASO are mentioned in Table 2. The criteria mentioned in the literature review were trimmed down to the most important criteria. Once the required inputs are defined, the next step is to establish a systematic evaluation process. This process involve identifying and gathering relevant data on different materials available in the market. The data include material properties, performance characteristics, quality criteria, and cost data. It is worth noting that cost-related criteria, such as initial and life cycle costs, are not included in this step, as cost evaluation is treated separately from the quality assessment in the value formula.

The determination of quality and performance criteria that can affect the process of cladding selection can be performed in a few ways: these include searching literature reviews and studying international material standards, which are useful when measuring quality criteria via proposed tests. Interviews with experts and construction market surveys also help determine the criteria (Lin, Yang, 1996). In this study, the Saudi Standards, Metrology, and Quality Organization [80] and other international standards mentioned above define quality standards through measurement testing.

All the proposed criteria were then evaluated and refined by presenting them to construction industry professionals. Five experts in the field, three architects and two civil engineering building professionals, reviewed the collected criteria and provided their insights and opinions on the significant criteria for facade selection based on their knowledge and experience. They extracted ten significant criteria, as shown in Table 2. Unrelated criteria were eliminated, with a limit of ten criteria being selected for this study. Selected criteria were measured in one of two ways: one was associated with measurement by standard defined tests or subjective measurement, which decision-makers or project designers define. Table 2 shows the measuring units of each criterion. In addition, the five subjective criteria, such as durability, aesthetics, cultural heritage, maintainability, and buildability, are often qualitative rather than quantitative, making them challenging to measure objectively. Unlike criteria that can be quantified, such as cost or energy efficiency, subjective criteria are more abstract and subjective. They are based on qualitative attributes that are difficult to quantify using standardized metrics. For example, while durability is primarily a qualitative attribute, it is challenging to measure directly as a quantitative value. Durability refers to the ability of a material or system to withstand wear, decay, or damage over time. It encompasses strength, resistance to environmental conditions, and longevity. There are indirect ways to assess and quantify durability, but it may be challenging to use these as standard methods.

Table 2. Criteria measurement explanation.

No.	Criteria	Measurement	Test Methodology
C1	Durability	Subjective	Evaluate it subjectively according to professional experts.
C2	Wind Load Resistance	Wind Pressure (kN/m2)	Evaluate it according to the Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Uniform Static Air Pressure Difference [81].
C3	Thermal Insulation	R-value	Evaluate it according to the International System of Units (SI) and the thermal resistance (R) equation [82,83].
C4	Fire Resistance	Fire Rate (h)	According to ASTM E2707-15 test.
C5	Aesthetic	Subjective	Evaluate it subjectively according to professional experts.
C6	Cultural Heritage	Subjective	Evaluate it subjectively according to professional experts.
C7	Maintainability	Subjective	Evaluate it subjectively according to a professional expert. However, several parameters are available for describing the maintainability characteristic of an item, such as Failure Rate, Mean Time to Repair
C8	Buildability	Subjective	Evaluate it according to a professional expert. However, several parameters are available for describing the buildability characteristic of an item, such as ease of construction.
C9	Sound Transmission	STC	The STC value for the exterior wall is determined according to [84].
C10	Weight	Kg/m2	The weight of the square meter of the cladding is adopted.

Table 2. Criteria measurement explanation.

No.	Criteria	Measurement	Test Methodology
C1	Durability	Subjective	Evaluate it subjectively according to professional experts.
C2	Wind Load Resistance	Wind Pressure (kN/m2)	Evaluate it according to the Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Uniform Static Air Pressure Difference [81].
C3	Thermal Insulation	R-value	Evaluate it according to the International System of Units (SI) and the thermal resistance (R) equation [82,83].
C4	Fire Resistance	Fire Rate (h)	According to ASTM E2707-15 test.
C5	Aesthetic	Subjective	Evaluate it subjectively according to professional experts.
C6	Cultural Heritage	Subjective	Evaluate it subjectively according to professional experts.
C7	Maintainability	Subjective	Evaluate it subjectively according to a professional expert. However, several parameters are available for describing the maintainability characteristic of an item, such as Failure Rate, Mean Time to Repair
C8	Buildability	Subjective	Evaluate it according to a professional expert. However, several parameters are available for describing the buildability characteristic of an item, such as ease of construction.
C9	Sound Transmission	STC	The STC value for the exterior wall is determined according to [84].
C10	Weight	Kg/m2	The weight of the square meter of the cladding is adopted.

3.3. Evaluate Criteria Weight (CW)

In the context of this research, criteria play a crucial role in the decision-making process, and their relative importance needs to be addressed appropriately. To ensure a comprehensive analysis, performance analysis is integrated with the criteria through the Performance Analysis System Technique (FAST) to meet the project goals diagram (Figure 2). Each criterion is linked to its relevant performance; some may be relevant to multiple performances. The SWARA method is selected as the Multi-Criteria Decision Making (MCDM) technique, employing a relative importance weighting approach. Subsequently, all criteria are evaluated based on their assigned weights to facilitate decision-making.

SWARA was used for the evaluation of the criteria weight. Aghdaie et al. [85] mention the framework of the proposed methods. The steps of criteria weights (CW) using SWARA are as follows:

Step 1. Identify and arrange the relevant evaluation criteria. The criteria are ranked based on anticipated significance from the most important to the least important criterion.

Step 2. Determine the comparative importance of average value. The comparative importance is determined from the criteria ranked in the second position, and the subsequent comparative importance is obtained by comparing criterion j and the previous criterion j − 1. Repeat this process for each criterion individually.

Step 3. Calculate the comparative coefficient k_j, which is obtained using Equations (2) and (3):

$$K_i=1 if i=1$$

(2)

$$K_i=S_i+1 if i>1$$

(3)

Step 4. Calculate the q_j. The weight $q_j$ is the unscaled weight given in Equations (4) and (5):

$$q_i=1 if i=1$$

(4)

$$q_i=\frac{S_{i-1}}{K_i} if i>1$$

(5)

Step 5. Calculate the scaled weight. Generally, MCDM criteria weights are scaled to one unit or 100%. Scaled weight (${\mathrm{W}}_i$) is calculated based on $q_i$ and the summation of all $q_i$ for all number criteria (n) using Equation (3):

$$W_i=\frac{q_i}{\sum _{i=1}^n{q}_i}$$

(6)

The $W_i$ of the ten criteria is shown in

Table 3. Weightage calculations obtained using SWARA.

No.	Criteria	Comparative avg. Value Sj	Coefficient Kj	Recalculated Weight qj	Final Weights Wj
C1	Durability		1	1	0.4706
C2	Wind load resistance	0.9	1.9	0.5263	0.2477
C3	Thermal insulation	0.888	1.888	0.2788	0.1312
C4	Fire resistance	0.875	1.875	0.1487	0.07
C5	Aesthetics	0.863	1.863	0.0798	0.0376
C6	Cultural heritage	0.85	1.85	0.0431	0.0203
C7	Maintainability	0.825	1.825	0.0236	0.0111
C8	Buildability	0.815	1.815	0.013	0.0061
C9	Sound transmission	0.75	1.75	0.0074	0.0035
C10	Weight	0.738	1.738	0.0043	0.002

. The essential criteria for the selection of façade material are durability, wind load resistance, and thermal insulation.

Sixteen experts received the questionnaire. There were 16 respondents in total, representing 100% of the total receivers. Among them, 25% held a Ph.D. degree, 25% held a master’s degree, and 43.8% held a bachelor’s degree. The respondents’ backgrounds were mainly in Architecture (56.3%) and Civil Engineering (25%). They had experience in various areas, including the following: Designers (37.5%), Contractors (25%), Consultants (18.8%), Client Representatives (12.5%), Academic Researchers (8.5%), and others. As mentioned in Section 3.2, the proposed framework determines the ten most important criteria. The framework was applied to determine criteria weightage (CW) for cladding materials using SWARA. Table 3 shows the weightage calculated. The essential criteria are durability, wind load resistance, and thermal insulation.

3.4. Calculate the Criteria Quality Weight (CQW) of Cladding Alternatives

For model development, it is essential to establish quality standards for each of the criteria. Mainly achieved through literature reviews, local and international standards and expert feedback have been used to find the best reference values for each cladding material criterion. The criteria that are hard to objectify or not available for judgment based on standards were considered subjective. Using the Delphi technique, a semi-structured interview was conducted with experts with experience in cladding and façades. These experts chose nine groups of common cladding materials in the construction industry. The selected material groups for this research model were metal composite material (MCM), building glass panels, natural stone panels, wooden panels, gypsum board panels, polyisocyanurate (PIR) and polyurethane (PUR) panels, high-pressure laminated (HPL, HPDL) sheets, fiberglass panels, and artificial stone. A structured interview was conducted with 16 experts to evaluate the 10 cladding materials for each subjective and objective criterion, the results of which are shown in

Table 4. Subjective and objective criteria values for different cladding materials.

Criteria	C1	C2	C3	C4	C5	C6	C7	C8	C9	C10
Units	---	KN/m2	m2.K/N	h	---	---	---	---	STC	Kg/m2
Aluminum Composite Material (ACM)	45	1	0.03	4	3.88	3.44	4.19	3.94	43	7.8
Coated Building Glass (CBG)	50	2.32	0.56	3	3.94	3	3.13	3.5	56	45
Natural Stone Panels (NSPs)	95	2.8	0.3	5	4.19	4.5	3.69	3.56	65	99
Wooden Panels (WPs)	50	1.6	0.17	1	4.56	4.25	3.5	3.69	50	20
Gypsum board Panels (GBPs)	45	1.1	0.07	2	2.88	2.31	3.69	3.81	40	10
Polyisocyanurate and Polyurethane (PIR-PUR)	25	1.5	0.04	1	3.06	3.19	4.25	4.19	55	10
High-Pressure Laminated Panel (HPLP)	43	1.3	0.1	3	4	3.06	4.19	4.06	60	12
Fiber Panels (FPs)	45	1.8	0.2	2	3.75	3.19	3.69	3.56	35	5
Artificial Stone Panels (ASPs)	60	1.3	0.2	4	4.63	4.06	4.31	3.94	60	60

. The assessment values of the five subjective criteria for the nine material façade alternatives are shown in

Table A6. Assessment of the five subjective criteria for aluminum composite material.

Aluminum Composite Material (ACM)	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	3	7	4	2		1.87
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	5	6	3	2		1.58
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	3	4	6	3		1.22
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	7	5	4			1.25
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	4	8	3	1		2.55

,

Table A7. Assessment of the five subjective criteria for gypsum board panels.

Gypsum Board Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	1	4	11	0		4.30
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	0	4	6	6		2.45
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	0	1	5	8	2	2.93
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	3	7	4	2	0	2.32
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	3	8	4	1		2.55

,

Table A8. Assessment of the five subjective criteria for artificial stone panels.

Artificial Stone Panel	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	0	6	10	0	0	4.12
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	11	4	1	0		4.30
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	6	5	5	0	0	2.64
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	8	5	3	0	0	3.06
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	8	4	8	1		2.95

,

Table A9. Assessment of the five subjective criteria for building glass panels.

Building Glass Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	3	8	5	0		2.92
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	5	6	4	1		1.87
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	3	2	5	4	2	1.17
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	2	5	3	5	1	1.60
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	4	4	5	2	1	1.47

,

Table A10. Assessment of the five subjective criteria for polyisocyanurate (PIR) and polyurethane (PUR) panels.

Polyisocyanurate (PIR) and Polyurethane (PUR) Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	0	0	1	10	5	3.87
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	0	6	5	5		2.35
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	0	7	5	4	0	2.79
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	7	6	3	0	0	2.93
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	8	4	3	1		2.55

,

Table A11. Assessment of the five subjective criteria for natural stone panels.

Natural Stone Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	12	4		0		4.99
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	8	4	3	1		2.55
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	10	4	2	0	0	3.71
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	3	7	4	2	0	2.32
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	4	4	5	3	0	1.72

,

Table A12. Assessment of the five subjective criteria for high-pressure laminated (HPL, HPDL) sheets.

High-Pressure Laminated (HPL, HPDL) Sheets	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	0	0	4	10	1	3.79
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	5	6	5	0		2.35
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	0	5	7	4	0	2.79
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	6	7	3	0	0	2.93
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	5	8	2	1		2.74

,

Table A13. Assessment of the five subjective criteria for wooden panels.

Wooden Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	2	5	9	0		3.39
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	10	5	1	0		3.94
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	8	4	4	0	0	2.99
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	3	4	7	2	0	2.32
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	4	6	3	3	0	1.94

and

Table A14. Assessment of the five subjective criteria for fiber cement panels.

Fiber Cement Panels	5	4	3	2	1	Standard Deviation
Durability: what is the expected age (lifetime) of the following material classification? Answer in years	0	5	10	1	0	3.87
Aesthetics: how good are the following materials visually, and do they increase the aesthetics of the building? Select 5 for best appearance to 1 for least worst appearance	4	4	8	0		2.83
Cultural heritage: how much of the following material categories are used based upon cultural reflection? Select 5 for the most relevant category and 1 for the least relevant category	0	6	7	3	0	2.93
Maintainability: how much maintainability following material categorization is required? Select 5 for least maintainable and 1 for most maintainable	2	8	5	1	0	2.93
Buildability: which material category facilitates ease of construction the most? Select 5 for the easiest-to-handle material and 1 for the hardest-to-handle material	3	4	8	1		2.55

in Appendix A.

The WASPAS method is preferred to the variety of available methods because of its ability to increase ranking accuracy. WASPAS enables the highest estimation accuracy by applying the suggested methodology for optimizing weighted aggregated performance. It combines two well-known methods, the weighted sum model (WSM) and the weighted product method (WPM), to provide an accuracy more significant than the original two methods, with aggregation optimization conducted. Figure 3 outlines a flowchart of the steps involved in the method. The steps of the method were applied as follows:

Step 1. Determine the optimal performance rating for each criterion. This step determines optimal performance as ($x_{i max}$) for beneficial value criteria and ($x_{i min}$) for nonbeneficial criteria.

Step 2. Construct the normalized decision matrix. The normalized performance ratings (criteria quality weight; CQW) are calculated using Equations (7) and (8) for beneficial and nonbeneficial values, respectively.

$${CQW}_{ij}=\frac{x_{ij}}{x_{i max}}$$

(7)

$${CQW}_{ij}=\frac{x_{i min}}{x_{ij}}$$

(8)

$CQWij$ denotes the normalized performance rating of the i-th alternative regarding the j-th criterion.

Step 3. Calculate the relative importance (quality weight) of the i-th alternative based on the weighted sum model (WSM) method. The relative importance (quality weight; QW) of the i-th alternative, based on the WS method, is calculated using Equation (9):

$${QW}_i^1=\sum _{j=1}^n{CQW}_{ij}.W_j$$

(9)

$Q_i^1$ denotes the relative importance of the i-th alternative regarding the j-th criterion based on the WSM method.

Step 4. Calculate the relative importance (quality weight; QW) of the i-th alternative based on the weighted product model (WPM) method. The relative importance of the i-th alternative, based on the WP method, is ascertained using the following equation:

$${\mathrm{Q}\mathrm{W}}_{\mathrm{i}}^2=\prod _{\mathrm{j}-1}^{\mathrm{n}}{\left({\mathrm{R}}_{\mathrm{i}\mathrm{j}}\right)}^{{\mathrm{W}}_j}$$

(10)

$Q_i^2$ denotes the relative importance of the i-th alternative based on the WPM method.

Step 5. Calculate the total relative importance of each alternative. The total relative importance, or more precisely, the joint generalized criterion of weighted aggregation of additive and multiplicative methods [23,48,61,86], is calculated using Equation (11).

$${\mathrm{Q}\mathrm{W}}_{\mathrm{i}}=0.5\sum _{\mathrm{j}=1}^{\mathrm{n}}{\mathrm{C}\mathrm{Q}\mathrm{W}}_{\mathrm{i}\mathrm{j}}.{\mathrm{W}}_{\mathrm{j}}+0.5\prod _{\mathrm{j}-1}^{\mathrm{n}}{\left({\mathrm{C}\mathrm{Q}\mathrm{W}}_{\mathrm{i}\mathrm{j}}\right)}^{{\mathrm{W}}_j}$$

(11)

3.5. Evaluate the LCC for Alternative Cladding Materials

The LCC was evaluated for each alternative material. Furthermore, LCC considers the material’s salvage value after the building’s expected life expectancy. According to the KSA experts, the salvage value of cladding material was ignored. In addition, the discount rate was set to zero to simplify the calculation of LCC. There are a few activities for maintaining and repairing cladding representing polish. In addition, the maintenance, repair, and salvage values of materials usually depend on the material and regional practices. In the KSA, these values are neglectable as these cladding materials generally do not require any maintenance; upon the completion of their life cycles, they are typically replaced, and companies that replace the old material do not charge as they use it for recycling purposes, neutralizing the salvage value.

The capital recovery cost (CRC) method calculates the total cost of owning and operating an asset over its useful life. It is used to compare the costs of different assets or to determine the feasibility of capital investment [87]. Due to ignoring the maintenance and repair costs and discount rate, this method was used in this study to compute LCC. The CRC is based on the initial cost (IC) and salvage cost (SC) and computed as Equation (12).

$$CRC=IC-SC$$

(12)

The CRC was considered an LCC. The IC, SC, CRC, and LCC of the different alternatives are shown in

Table 5. Life cycle cost of different alternative materials.

Materials	ACM	CBG	NSP	WP	GBP	PIR-PUR	HPL	FP	ASP
IC	450	550	300	780	85	200	325	210	300
SC	0	0	0	0	0	0	0	0	0
CRC = LCC	450	550	300	780	85	200	325	210	300
Normalized LCC	0.58	0.71	0.38	1	0.11	0.26	0.42	0.27	0.38

. The $\overline{LCC}$ for each alternative can be calculated by normalizing its value with the obtained LCC maximum value.

3.6. Compute VE and Select the Best Alternative Cladding Material

The maximum quality weight (QW) and least-costed material should reflect the most favored material adaptation, considered by computing VE, which is the ratio of QW to LCC. Each alternative cladding material receives a value ratio by applying this equation to all alternative materials. The highest VE is the preferred alternative material.

3.7. Integrate the Proposed Framework with BIM

Integrating the proposed framework with the BIM model enhances its value by embedding all studied material types, properties, and criteria values. The evaluation process links these data with the BIM model through the API platform, enabling the automatic calculation of criteria scores, quantity, and total cost upon material selection. This instant feedback empowers decision-makers to assess the impact of their choices. In this research, Autodesk Revit software version 2023, widely recognized and utilized by architecture, engineering, and construction professionals, served as the BIM platform. Dynamo programming, an open-source tool that facilitates visual programming and grants access to the Revit API, was employed to manipulate graphic elements known as “nodes” and automate tasks [88], as shown in Figure 4. Additionally, Dynamo allows for the use of Python programming for more advanced performances, extending its capabilities.

Table A15. Added parameters.

Parameters Group	Parameter Names	Assigned Category	Parameter Name Prefix	Parameter Type
Criteria Parameters	CR.01. Durability		CR. XX.	Number
	CR.02. Wind load resistance	Cladding Materials
	CR.03. Thermal insulation
	CR.04. Fire resistance
	CR.05. Aesthetics
	CR.06. Cultural heritage
	CR.07. Maintainability
	CR.08. Buildability
	CR.09. Sound transition
	CR.10. Weight
Benefit	BC.01. Beneficial	Project Information	BC. XX.	Yes/No
	BC.02. Beneficial
	BC.03. Beneficial
	BC.04. Beneficial
	BC.05. Beneficial
	BC.06. Beneficial
	BC.07. Beneficial
	BC.08. Beneficial
	BC.09. Beneficial
	BC.10. Non-beneficial
Weights Parameters	WP.01. Durability	Project Information	WP. XX.	Number
	WP.02. Wind load resistance
	WP.03. Thermal insulation
	WP.04. Fire resistance
	WP.05. Aesthetics
	WP.06. Cultural heritage
	WP.07. Maintainability
	WP.08. Buildability
	WP.09. Sound transition
	WP.10. Weight
Cost Parameters	LCC Cost	Cladding Materials	N/A	Number
Value Output Parameters	Cost	Cladding Materials	N/A	Number
	Normalized Quality
	Normalized Value

, as shown in Appendix A, displays the additional parameters that were utilized during the calculation process. Some of these parameters are used for inputting data, such as determining the benefit/non-benefit of each criterion, assigning the weight of the ten criteria, and determining information cost, while others are used for outputting data.

To complete the calculation process, all criteria must be defined as parameters. The parameters in Revit were assigned to the cladding materials category. They allow the user to assign any type of data, and they can be linked with each other. The BIM model process involves fully modeling all building cladding alternatives, specifying material specifications, including different properties. While performing the calculation, defining all the criteria as parameters is essential. These parameters can be assigned to different categories within Revit. Using parameters allows users to assign and connect various data types using specific formulas.

Regarding modeling the cladding options, first, all the different cladding options need to be created in a model. Additionally, specific details about the materials used for each option must be specified. Then, the data on the materials should be entered. Next, values for all the quality criteria must be assigned to each material option. Additionally, cost information needs to be included. These data can be entered manually or linked to an external database via Excel, as shown in Figure 4 and Figure 5. After that, the project information is inserted into the criteria. All relevant data regarding the project must be defined. This step includes factors such as the importance or weights assigned to each criterion based on the project’s specific requirements. Once all the necessary inputs are entered, the calculation process can be initiated to run the calculation program. This process determines the best selection of materials based on their overall values. The different alternative materials are ranked, and the results are displayed.

4. Case Study

The developed framework was implemented in the case study, specifically after the accomplishment of the construction phase and throughout the operation phase. A case study of an office building was considered to validate the proposed methodology’s effectiveness. The construction of the case study started in June 2009 and was completed in June 2014. Specific details on the building, including its purpose, size, location, and design, were provided. The material selection process was applied to the case study. This process involves collecting relevant data on available materials, evaluating them based on the defined inputs, and making informed decisions on cladding material selection for the building.

4.1. Description

The office building in Riyadh, King Saud University Endowment, in Riyadh, KSA, has a covered area of 32,016 m², with a ground floor area of 5700 m². Figure 5a,b show the plan and 3D view. The building stakeholders expressed a desire to change the façade of the building from ceramic to an alternative material to reflect its cultural importance in addition to the other significant criteria mentioned in the developed framework. The objective was to enhance the aesthetic appeal and align the building design with the cultural context of the region. The decision to transition from ceramic to an alternative material as the cladding material was driven by the stakeholders’ recognition of the significance of cultural heritage and their aim to create a visually appealing façade that resonates with the local context.

4.2. Applying the Framework in the Case Study

Our study focused on three alternatives for the office building: aluminum cladding, Riyadh stone, and granite. The client had chosen these materials as alternatives to replace the existing ceramic cladding. A questionnaire was developed and submitted to experts with working experience in KSA to validate the selected criteria, which was further used in the evaluation to determine the weighted criteria. Sixteen experts received the questionnaire.

4.2.1. Alternative Material Calculations

Objective criteria were prioritized based on the material data and specifications, while subjective criteria were ranked based on professionals’ expertise, including architects, engineers, and project managers. It is essential to note that specific measurements necessitate expensive tests; therefore, an experienced quality engineer estimates wind load resistance, thermal insulation, and fire resistance based on their expertise. International standard tests were used for the objective criteria, and experts’ input was used to evaluate the subjective criteria. WASPAS was used to evaluate criteria for quality weightage CQW.

Table 6. CQW according to international standards and experts.

Criteria		C1	C2	C3	C4	C5	C6	C7	C8	C9	C10
Unit		---	KN/m2	m2.K/N	h	--	---	---	---	STC	Kg/m2
Criterion Weight (CW)		0.5	0.2	0.1	0.1	0	0	0	0	0	0
Optimal Reference Values		4	2.8	0	5	4.6	4.5	4.3	3.9	56	99
Aluminum Composite Panel (ACP)	V	2	1	0	4	3.9	3.4	4.2	3.9	43	7.8
	N	0.5	0.4	1	0.8	0.8	0.8	1	1	0.8	0.1
Riyadh Stone (RS)	V	3	1.3	0	5	4.2	4.5	3.7	3.6	56	99
	N	0.8	0.5	1	1	0.9	1	0.9	0.9	1	1
Granite (GRT)	V	4	2.8	0	4	4.6	4.1	4.3	3.9	55	52
	N	1	1	0.2	0.8	1	0.9	1	1	1	0.5

shows the calculation, which consists of criteria measuring the optimum value to analyze the chosen alternative building materials, i.e., Riyadh stone, aluminum composite panel, and granite. The normalization process aims to transform the raw data into a standardized scale, allowing for meaningful comparisons. The normalized values reflect the relative performance of each alternative material for each criterion, providing a basis for decision-making.

Once the values of the decision matrix are normalized, the WSM and WPM values are calculated to determine the QW of each alternative material.

Table 7. WASPAS results.

Alternative Materials	0.5 WSM	0.5 WPM	0.5 WSM + 0.5 WPM
ACP	0.579	0.539	0.559
RS	0.749	0.718	0.733
GRT	0.887	0.807	0.847

shows the CQW for the three alternative cladding materials (ACP, RS, and GRT). The CQW is the summation of the half-value of WSP and WPM.

4.2.2. LCC Computation

Cost data were gathered by consulting different estimation experts and obtaining input from the local market. The initial cost (IC) was calculated while keeping these factors in mind. After consultation with engineers with experience in costing and local market vendors, the average pricing of the selected alternative materials was determined. LCC values were calculated using the annual worth method outlined in Section 3.5. The (LCC) values of ACM, RS, and GRT were 0.58, 0.38, and 0.45, respectively.

4.2.3. VE Determination

By dividing the Q by the LCC, the VE equation quantitatively measures the value derived from each alternative. A higher value for VE indicates a better value proposition, which signifies a higher quality-to-cost ratio for that alternative. This score can then be used to compare and rank different alternatives, aiding decision-makers in selecting the most favorable option for optimizing value within the given cost constraints. The VE values of ACM, RS, and GRT were 0.96, 1.92, and 1.88, respectively. Therefore, the best cladding material was RS.

4.2.4. BIM Modeling and Calculation

The Revit model incorporates all the chosen building cladding materials and the corresponding criteria weights and values. These inputs were efficiently imported from an Excel sheet using Dynamo. Additionally, the LCC costs for the materials were included. The calculations outlined in Section 3.7 were performed. The model computes the quality scores and values, presenting the alternatives with the highest value first and descending to the lowest. Moreover, it displays the values of all the other material criteria.

4.3. Discussion

The capability of the façade materials to endure different operating and environmental circumstances over a long period is known as durability. Lee [10] stated that durability is a critical issue for building façade. Weather, temperature changes, UV radiation, pollution, and physical impacts are all environmental factors that affect the façade and its durability performance [10]. Durable materials ensure the long-term performance and operation of the façade by withstanding these elements without experiencing severe degradation. Choosing sturdy façade materials can also save money throughout the building’s life. Durable materials save related costs, requiring less frequent maintenance, replacement, and repairs. Building owners can achieve long-term cost efficiency by extending the façade’s lifespan, reducing maintenance costs, and averting premature failures by investing in durable materials upfront.

Regarding the wind load resistance criteria, façades are exposed to wind forces, including gusts, pressure differentials, and vortex shedding. Wind load resistance ensures that the façade materials can withstand these forces without experiencing excessive deflection, deformation, or failure. By selecting materials with high wind load resistance, the structural safety of the building is enhanced, minimizing the risk of façade damage or collapse. Wang et al. [89] utilized the wind load as the main parameter for the design optimization of building façades. Moreover, building codes and regulations often include specific requirements and guidelines related to wind load resistance. Compliance with these codes is essential for obtaining permits and ensuring the building meets safety standards. Selecting façade materials with the appropriate wind load resistance ensures compliance with regulatory requirements and facilitates approval.

Thermal insulation helps reduce heat transfer through the building envelope, including the façade. By selecting materials with high thermal insulation properties, the building’s energy efficiency is improved. Insulated façades minimize heat loss during colder seasons and heat gain during warmer seasons, reducing reliance on heating, ventilation, and air conditioning (HVAC) systems. This improvement leads to lower energy consumption, a reduced carbon footprint, and potential cost savings on energy bills. Furthermore, effective thermal insulation contributes to a more comfortable indoor environment for building occupants. Insulated façades help maintain a stable and comfortable indoor temperature by reducing temperature fluctuations near exterior walls. This criterion creates a more pleasant living or working environment, improving occupant satisfaction, productivity, and overall well-being. According to Alkhataib et al. [90], a primary goal in building design and operation is to preserve occupant comfort while consuming minimal amounts of energy. Alkhataib et al. [90] also pointed out that a building’s façade behavior and thermophysical characteristics frequently determine its interior conditions.

In contrast, the results of the framework indicate that the weight criterion is the least significant of the top ten criteria, with a weight of 0.01; however, this criterion is significant in selecting façade materials for tall buildings [91].

The building façade is part of the overall design and is created during the design stage. This stage provides several safe options for interfaces. Then, the proposed method is used to choose the best alternative from among those proposed alternatives. Therefore, the proposed framework can be integrated with the general framework of the design.

Regarding the discussion of the case study’s results, in the VE method, the higher the normalized value score, the better the performance of the alternative. Aluminum cladding has a normalized value score (V) of 0.96, Riyadh stone has a V of 1.92, and granite has a V of 1.88. These results indicate that granite is the best-performing alternative among the three, followed by Riyadh stone and aluminum cladding. Riyadh stone stood out due to its favorable cost criteria and enhanced aesthetic value; most importantly, it is a locally produced material with a close connection to the cultural heritage of Riyadh city, and it closely rivals the quality standards of granite. On the other hand, aluminum cladding showcased advantages in terms of buildability and maintainability despite its relatively lower fire resistance and lifespan.

The stakeholders intended to incorporate traditional elements into the building design by opting for Riyadh stone, paying homage to the region’s cultural heritage, as shown in Figure 6. This change in the façade material was aimed at establishing a stronger connection between the building and its surroundings, fostering a sense of identity and cultural pride. Riyadh stone is a commonly used material due to its timeless and elegant appearance, enhancing overall aesthetics. It is deeply rooted in architectural history and cultural heritage. A range of finishes, textures, and patterns are available, ensuring versatility in design. It requires minimal upkeep and efficiently retains its original beauty, so it is low-maintenance with maximum sustainability, represents a natural and abundant material, and has a low environmental impact. Riyadh stone also exhibits excellent insulation properties, enhancing energy efficiency, and withstands harsh weather conditions, ensuring a long-lasting façade. Some renowned examples of using similar cladding material for building façades are located at the University of Oxford in Oxford, UK, which is an educational campus. Yellow limestone cladding is integrated into various buildings across the campus, exuding a sense of tradition and architectural charm. Washington National Cathedral, situated in Washington, DC, is a religious structure with yellow and off-white limestone cladding applied, symbolizing the strength and timelessness of the cathedral’s design. Salamanca Cathedral, another religious structure in Spain, features yellow limestone cladding on its exterior, accentuating the intricate Gothic architecture and historical prominence. The Federal Hall National Memorial, located in New York, USA, is a historic landmark; yellow to brown limestone cladding is utilized to preserve the building’s historical integrity and architectural elegance.

The case study findings were shared with the specialized experts. These experts possessed extensive experience of over 15 years in the construction industry. They were asked to indicate their satisfaction level using a Likert scale, including QW, LCC, criteria weights, and overall value results. A summary of their responses is presented in

Table 8. Experts’ satisfaction.

No.	The Data	Experts’ Satisfaction %
1	Criteria Weights	86%
2	Quality Values	90%
3	Life Cycle Cost Values	85%
4	Overall Value Results	90%
	Standard Deviation	2.27%

.

The experts’ opinions indicate that the proposed framework yields reliable results that can be effectively employed for the evaluation of materials. However, the experts provided the following comments regarding the case study results: one expert expressed the belief that for office buildings in KSA, greater emphasis should be placed on the aesthetic and cultural aspects than other considerations. Due to their proper use, another expert opined that maintenance and repair work for building cladding in office buildings might be necessary. As a result, the total life cycle cost equation could be formulated by combining the initial cost with the maintenance and repair cost.

5. Conclusions

This paper presents a methodology for evaluating and selecting cladding materials for office building projects. The methodology employs multi-criteria decision-making (MCDM) techniques to address the complexities and varying priorities involved in material selection, which consists of several steps. The first step reflects the data collection criteria and involved a study of previous studies, books, international material standards, and several international quality standards. Then, by conducting semi-structured interviews with Saudi construction experts, criteria appropriate for the Saudi market were identified and selected. Next, the weights of the chosen criteria were established using the SWARA approach. The WASPAS technique was used to evaluate the quality weight (QW) of common cladding materials. The LCC of the typical cladding materials was then assessed. The VE of each alternative cladding material was computed based on the QW and LCC values. After that, the best alternative was selected based on the highest VE value. Finally, the process was linked with the BIM approach to automate the evaluation, defining the required parameters and the workflow of the BIM calculation. Owing to this integration, decision-makers may now see the consequences of their material decisions. Moreover, a case study of an office building was reported to provide a better understanding of the evaluation process. The case study results showed that granite has the highest value score. However, Riyadh stone was the best-performing alternative among the three alternative materials, followed by granite and aluminum composite panels. Riyadh stone scored the highest in durability, aesthetics, cultural heritage, and thermal insulation. It also had a relatively low cost and a long lifespan. Granite was the best-performing alternative in terms of fire resistance and lifespan. However, it had a higher cost than Riyadh stone and was not as locally produced. Aluminum composite panels had the lowest cost among the three alternatives but had a lower fire resistance and lifespan than the other two alternatives. As a result of the literature review and expert evaluation, ten essential criteria for selecting building materials were identified. The three most significant criteria were durability, wind load resistance, and thermal insulation. This method was used after the design stage to study the available alternatives proposed by the designers and to choose the best alternative. The case study findings were validated by a panel of experts who were satisfied with the results of the framework. The experts also made some suggestions for improvement, such as emphasizing the aesthetic and cultural aspects of cladding materials in office buildings in the KSA. Additionally, the experts suggested that the total life cycle cost equation should be formulated by combining the initial cost with the maintenance and repair costs. In addition, the experts also evaluated the quality values, cost values, criterion weights, and overall value results. The satisfaction average surpassed 80%, affirming the proposed framework’s reliability in evaluating the value of each alternative material. This study provides valuable insights and practical guidance for decision-makers in the construction industry, enabling them to make informed choices regarding building cladding materials. The methodology provides a comprehensive framework for choosing building façade materials. It integrates decision-making procedures with BIM to automate the VE concept. This integration streamlines the material selection and evaluation process, ensuring efficient decision-making. The weighted evaluation of criteria using the SWARA technique involve subjective judgments. Stakeholders may assign different weights to the requirements, leading to potential bias in the results. Future work should explore methods to minimize subjectivity and enhance the objectivity of weight evaluation. The methodology computes the life cycle cost (LCC) of alternative cladding materials but only considers some cost factors comprehensively. Future work should incorporate a more detailed and accurate cost evaluation, including maintenance costs, operational costs, and potential future savings. The methodology focuses primarily on technical and economic criteria. Future work should consider incorporating an assessment of the environmental impact of cladding materials. Assessing the environmental impact would involve evaluating factors such as embodied energy, carbon footprint, resource depletion, and recyclability. The methodology outlined in this paper was tested in a specific context in the KSA, but future research is necessary to assess how it performs in other contexts. It would be helpful to analyze how these results would vary if different experts were consulted; the results could be enhanced using automated data entry in BIM to optimize these processes.