Evaluating formwork systems through sustainability metrics for smart city infrastructure projects

Abstract

Smart city development is building in a manner that is good for the environment, makes the most money, and utilizes resources intelligently. Formwork procedures, which are highly significant in building with concrete, have a large effect on these outcomes for sustainability. This research analyzes and compares six different formwork systems: tunnel formwork, plastic, modular, aluminum, and steel. The assessment is based on measures related to construction performance, economics, and environmental effect. We used the weighted aggregate method in order to find the normalized sustainability indicators. The results were confirmed and the most essential factors were identified through sensitivity analysis. This was also used to show the solidity of the findings. The results show that with the changing of old systems into new, the performance of sustainability is definitely improving. The general rating of the sustainability of the wood formwork was about 0.45. The ratio decreased to about 0.85 to 0.88 which is an increase of 90 percent on aluminum and tunnel formwork. The increase in performance of the environment and construction was over 120 and 110 percent respectively between timber and tunnel formwork. This implies that the contemporary processes are more efficient, quicker and consume less material. Even when they are more expensive initially, in the long run, modular, aluminum, and tunnel formwork would be 30 to 40 percent less expensive than wood. These observations indicate that the modern formwork methods are excellent in large, long-term, and repetitive construction works. The engineers and policymakers are aided by this information. The proposed appraisal system is an effective and adaptable method in the effort to help people make decisions about formwork. This will enable it to build infrastructure that is more environmentally friendly to create smart cities. It also considers the concerns with regard to the functioning of the economy, and the environment. The multi-criteria decision-making (MCDM) techniques of the Analytic hierarchies Process (AHP), Technique Order Preference by similarity to ideal solution (TOPSIS), Preference Ranking Organization Methodology to enrichment Evaluation (PROMETHEE), and different Life-cycle Assessment (LCA) models have been widely used in the recent research of construction sustainability assessment to attribute environmental impacts on construction materials and systems. These systems facilitate organized evaluation of alternatives using various performance measures such as cost effectiveness, environmental degradation, energy usage and social consequences. Much of this type of approach, however, involves complex pair wise comparisons, big data or specialized decision matrices that can restrict their application to normal construction project evaluation. To overcome these issues, the current paper presents a systematic approach to sustainability evaluation in the form of a weighted aggregate approach according to which various sustainability indicators are combined in one computational framework. The given framework enables systematic normalization, weighting, and aggregation of sustainability indicators, thus offering a clear comparison of construction technologies e.g. MIVAN and traditional formwork systems.

1 Introduction

The infrastructure systems should be robust, efficient and durable because the cities and the population are growing at such an alarming rate. A smart city is aimed at improving the life of a city by integrating the latest technology, effective management of resources as well as building techniques that are environmentally friendly. The construction of smart cities is most essential as the construction industry consumes much energy, materials, and pollution. Due to this, the use of green construction technologies has become of big interest to civil engineers, parliamentarians and city planners everywhere across the world (Nilimaa and Zhaka, 2023). The way you construct formwork is of significant determination to the longevity, price, speed of erection, functionality, and environmental conservation. The formwork can constitute 40%–60% of the general price of a concrete construction. It also influences the level of wasted material, construction time and productivity of the workers (Taher Ahmed et al., 2014). Formwork usually is of wood or steel. However, they often leave a lot of rubbish, require repairing regularly, increase the difficulty of work to employees and damage the environment. However, modern forms of formwork (aluminum, plastic, modular, tunnel formwork) are stronger, can be recycled, are also more accurate and have fewer impacts on the environment during their usage. It means that they are more effective in applying to large infrastructure projects of smart cities (Al-Ashwa, 2020).

Sustainability in the process of construction requires more than just the use of the correct materials. It also involves a close examination of the performance of the economy, the society and the environment. The ways of figuring out the duration of a building system are good in a lot of ways. You can consider issues such as the cost of living with it, amount of energy consumed, amount of carbon emitted, amount of waste emitted, how fast it can be constructed, its safety and its functionality (Li et al., 2022). In the process of selecting the most appropriate formwork system in building smart cities, the trade-offs are frequently between the cost in the short run, benefits in the long run, and environmental impact. The available literature lacks systematic or metric-based evaluations of different formwork solutions within the framework of smart cities development, despite the increase in the number of users of the advanced formwork systems (Asadi and Praneeth, 2017). The infrastructural projects that involve smart cities usually incorporate high-rise, repetitive and mass-housing complexes. The formwork is a large constituent of the appropriateness of the project functioning and its environmental friendliness. By applying improper formwork, you might find it taking longer, wastage of materials, decrease, and leave a larger carbon footprint on the buildings. Cities such as Smart cities do not desire such things (Mistry et al., 2023). Clear sustainability standards should be applied in the evaluation of the formwork systems.

This will assist people in making improved decisions as well as better building techniques where less resources are used. This research aims to provide an analysis and comparison of various formwork systems through the prism of sustainability parameters applicable to the project of smart cities infrastructure. The research examines the various formworks depending on their cost-effectiveness, environmental friendliness, efficiency and durability. This project aims at identifying how to integrate the traditional form of building with the smart cities requirements such that the buildings can serve a long life. The results are supposed to help the engineers, contractors and politicians settle on the most appropriate formwork solutions that are aligned with the highest civil engineering standards in all parts of the world and the objectives of sustainable development (Wikipedia, 2025a). Timber and steel formwork have been in use since ages because they are easily available, low-cost to install and individuals understand how to use them. However, such systems frequently fail to be accurate, they need repair, are advantageous to the environment and can be reused. People are fearful of the length of time wood formwork takes, the amount of rubbish it produces and deforestation. The steel formwork on the other-hand, has problems with corrosion, consumes a lot of energy and releases air pollution during shipping (Al-Ashwa, 2020). To circumvent these issues, new formwork technologies such as aluminum, plastic, modular, tunnel and engineered composite formworks have been developed. Such techniques allow increased repetition cycles, dimensional accuracy, reduced building times and increased safety requirements. These characteristics render the use of advanced formwork solutions increasingly applicable in smart city infrastructural endeavors that require the ability to be fast, adaptable, and sustainable (Wikipedia, 2025b).

Sustainability assessment in construction has evolved into a system as a whole that comprises of social, economic, and environmental performance measures. Besides such environmental indicators like embodied energy, carbon emission, material efficiency, and waste minimization, there are the economic ones such as lifetime cost, productivity and durability and the social variables such as the workforce safety, quality of construction and community impact (Krasnov, 2024). This seems to be a wide definition of sustainability but people often select formwork systems depending on the amount of expenditure they will entail during their first use, rather than how long they will be used. The gap between the theory of sustainability and the practice of construction is an indication of the need to use systematic assessment tools that put into consideration sustainability in the decision on formwork (Balasbaneh et al., 2024).

The smart city infrastructure is difficult to establish as the projects are large, have to be completed in a short time span and require a large variety of technology types to be used. Making environmentally-friendly and long lasting smart public transportation systems, smart neighborhoods, and shopping malls should not be a difficult thing. Failure to select the right formwork may also make you work harder, waste materials, spend more time finishing the project and damage the environment during the process. This does not agree with the concept of smart cities (Hanna, 1999). Sustainability indicators should be used to evaluate formwork systems in order to ensure that the structure of buildings being constructed and the objectives of smart cities serve the same purpose. Other previous researches have examined some types of formwork systems or have analyzed other alternatives to determine which one is the most economical. Nevertheless, the sustainability of smart city infrastructure has been carefully assessed very few times. The methodology employed in the present research is lacking and simultaneously analyses environmental performance, financial viability, architectural efficacy, and long-term sustainability benefits (Wu et al., 2023). The research issue must be remedied so that the judgments on building are founded on actual data and formwork technology continues to improve. The study evaluates formwork systems based on the sustainability measures that apply to the smart city infrastructure projects. The project intends to employ quantitative sustainability indicators relevant to the modern day urban planning so as to be able to compare a holistic comparison between traditional and modern formwork systems. The aim of the project is to help the builders, engineers, and politicians make the most appropriate decisions in selection of the best varieties of the formwork that are also least destructive to the environment. The proposed study aims at improving ecologically friendly methods of construction and supporting the achievement of the main goals in the development of smart cities and corresponding to international requirements in the area of civil engineering and sustainable development objectives (Alashwal et al., 2012). This study contributes to the existing body of knowledge in three key ways. First, it proposes a simplified and transparent sustainability assessment framework based on weighted aggregation, addressing the practical limitations of conventional multi-criteria decision-making methods such as AHP and TOPSIS, which often involve complex computations and large data requirements. Second, the study advances construction management theory by integrating lifecycle cost considerations, construction efficiency, and environmental performance into a unified evaluation model. This enables a more holistic understanding of construction system performance beyond traditional cost-based decision-making. Third, the proposed framework aligns with smart city development principles, particularly in terms of scalability, rapid construction, and resource efficiency. By focusing on formwork systems as a critical component of reinforced concrete construction, the study establishes a link between micro-level construction technologies and macro-level sustainability objectives in urban infrastructure development.

Sustainability assessment in construction has been widely studied within the framework of multi-criteria decision-making and lifecycle analysis. Existing approaches often rely on complex hierarchical models or data-intensive techniques, which may limit their applicability in practical decision-making scenarios. In the context of construction management, there is an increasing emphasis on integrating operational efficiency with environmental and economic sustainability. Similarly, smart city frameworks highlight the importance of scalable, resource-efficient construction technologies. However, there remains a gap in developing simplified, integrative evaluation models that can effectively support technology selection in infrastructure projects. The present study addresses this gap by proposing a structured yet computationally efficient assessment framework.

2 Methodology

The sustainability assessment approach used in this paper is based on the existing multi-criteria decision-making principles with a weighted aggregate evaluation framework adopted. Compared to hierarchical approaches of ranking, e.g., AHP or distance-based approaches, e.g., TOPSIS, the weighted aggregate method is a direct combination of normalized performance measures with pre-defined weights of the criteria to obtain a composite sustainability score. This method gives a clear computational framework that enables easy comparison of other structure of construction systems. The proposed methodology brings about sustainability indicators on three broad areas of construction sustainability namely; environmental performance, economic efficiency, and construction productivity. All the dimensions are comprised of quantifiable attributes like material consumption, construction cost, waste production, labor productivity, and construction period. The indicators are initially normalized to remove the variation in measurement units and scale. After that, each indicator is given weights depending on its weight contribution to sustainability assessment. Weighened normalized indicators are further summed to give a composite sustainability index of each construction technology in consideration. This framework allows the systematic comparison of such alternative construction technologies as MIVAN formwork and traditional formwork systems and provides the methodological clarity and computational transparency.

2.1 Overall research framework

The method used in this research is specifically designed to accomplish this, i.e., to take a systematic look of how well a series of formwork systems deployed in infrastructure projects in the smart city are capable of surviving. This research is carried out in stages, starting with the identification of the system, selection of indicators of sustainability, data acquisition, normalization, weighting, comparison, and validation. The research uses a hybrid approach where both qualitative and quantitative methods of evaluation are incorporated in a multi-criteria decision model approach to examine the intricate and connected dimensions of sustainability of formwork alternatives. The methodological approach favors clarity, repeatability, and practical applicability in the real life construction situations and all these are critical in international civil engineering research (Lodha and Tambe, 2017).

2.2 Selection and classification of formwork systems

In order to know how to use formwork, we have to read as much as we can about various research articles, building codes and how things are being done in the reinforced concrete construction sector at the moment. It was selected on the basis of the systems that are common or increasingly common in the infrastructure projects of the big cities, and particularly the ones that the city must be made smarter. Formwork systems were of two major types, old and new. This has been done to demonstrate the transformations of technology and its effectiveness. The traditional building people still use wood and steel formwork as it is readily available and people are accustomed to it. The material chosen to use in the study was the new material such as aluminum, modular, plastic, and tunnel formwork as it is increasingly being employed in a project that requires multiple homes to be built simultaneously such as high-rise buildings. This categorization ensures that the assessment scheme incorporates old and modern methods of construction.

2.3 Development of sustainability assessment criteria

The standards of the sustainability evaluation were formulated in a manner that would make the assessment of the effectiveness of the formwork systems in different situations comprehensive. The selection criteria were according to concepts of sustainability, building smart cities requirements, and the general consensus in the field of civil engineering. Sustainability indicators were three in essence and included environmental sustainability, economic sustainability, and building performance sustainability. Environmental indicators examine things such as the efficiency of material use, their frequency of reuse, amount of waste, and amount of energy when used in formwork (Thiyagarajan et al., 2017). The economic indicators focus on the initial investment, the cost incurred in the long run, the manpower required and its impact on productivity. Construction performance indicators can be the pace of construction, the quality of the work, its safety, ease of assembly and disassembly, ability to endure several building cycles, and so on. With such additions, you will be assured that the evaluation process will consider the short-term construction performance as well as the long-term considerations on the sustainability.

2.4 Sustainability evaluation framework

The sustainability assessment of formwork systems should have an analytical framework that is organized and can combine various performance measures on construction efficiency, economic feasibility, and environmental impact. The choice of formwork systems has a great impact on construction rate, cost of the project, material use, and environmental output in the infrastructure development projects, especially those linked to smart cities. Consequently, there is a need to design a multi-criteria evaluation system that will compare alternative formwork systems in terms of their overall performance in terms of sustainability. In this work, six formwork systems were considered widely used such as timber formwork, steel formwork, plastic formwork, modular formwork, aluminum formwork, and tunnel formwork. It was evaluated based on a weighted aggregate approach hence enable combining several sustainability variables into one composite index. This technique is extensively applied to multi-criteria decision-making researches, as the technique offers a clear-cut system of integrating indicators by various measurement units and importance. The suggested framework assesses the formwork systems on three broad sustainability areas namely construction performance, economic performance and environmental performance. Every dimension is made up of several indicators that all combine to portray the operational and environmental property of the formwork systems. Wighed aggregation method makes sure that the input of each indicator is proportional to its weight in the evaluation model. The sustainability performance of the individual formwork systems was measured by the way of a composite sustainability index based on the weighted sum of the normalized sustainability indicators. The mathematical formulation of weighted aggregate method is given as:

where: , sustainability index of the i-th formwork system; , weight assigned to the j-th sustainability indicator; , normalized value of indicator j for formwork system i; n, total number of sustainability indicators.

This expression is used to multiply the normalized performance values with the weighting coefficients and comes up with one composite score that depicts the sustainability performance of each formwork alternative. The total weight of the weights used in the weighting structure should be normalized to the following constraint:

This condition also makes the overall contribution of all the indicators balanced and also makes the index of sustainability to be in a standard range. The sustainability index values are higher, which means that the overall sustainability performance is higher. The weighted aggregate approach was chosen because of its transparency, ease of calculation, and the possibility to combine the heterogeneous indicators into a single assessment system.

2.5 Data collection strategy

It was gathered after consulting numerous credible sources to ensure that it was accurate and could be relied on. These sources are peer-reviewed journal publications, technical manuals, manufacturer specification, industry reports, and documented case studies of urban infrastructure developments. The amount of quantitative information we gathered was as much as we were able to get including the reuse cycles, cost aspects, labor productivity, and building time. Our qualitative information about safety, ease of manipulation, and quality of building was gathered through the research that was already made and the knowledge of professionals within the literature. All the data that was acquired was thoroughly examined to ensure that nothing was different and it was sorted based on the established sustainability standards (Gulghane et al., 2018). The dataset used in this study is not derived from a single project but represents a synthesized benchmark dataset compiled from multiple literature sources, technical reports, and documented case studies. The collected data reflect typical performance ranges observed across 15–25 infrastructure and high-rise construction projects.

2.6 Data sources

The framework of sustainability assessment that was created in this paper is founded on the dataset that was gathered on the basis of various sources devoted to construction project performance and formwork systems use. The data were gathered based on research articles, technical reports on construction, contractor report and industry guidelines on formwork technologies that were employed in reinforced concrete construction. These sources offer empirical performance levels of different sustainability indicators such as construction time cycle, productivity of labor, material usage, re-use possibilities and production of waste. To boost accuracy of the data, data were triangulated by using different documented projects in which the same construction technologies were used. Besides the secondary literature sources, the perspectives of the construction practitioners as well as the project engineers who worked on high-rise and repetitive housing projects were also used to justify the applicability of the performance indicators. In the study, 6 popular formwork systems that are widely applied in the modern construction practice are evaluated. These are timber formwork, steel formwork, plastic formwork, modular formwork, aluminum formwork and tunnel formwork. The choice of these systems is due to the range that they provide to cover the traditional and modern construction technologies available in the infrastructure and mass housing building processes. Data on the performance of the formwork systems of the type were obtained in a series of sustainability indicators that were classified into the following construction performance, economic performance and environmental impact. The dataset is thus an organized comparison of formwork technologies in terms of quantifiable performance characteristics in terms of smart city infrastructure project. The dataset is structured in the form of a decision matrix where rows represent formwork alternatives and columns represent sustainability indicators. Each data point is categorized as empirical (directly reported), derived (aggregated from multiple sources), or assumption-based (for qualitative indicators converted into ordinal scores). The dataset used for sustainability evaluation consists of six formwork systems evaluated across nine sustainability indicators. The dataset follows a structured matrix format where each row corresponds to a formwork alternative and each column corresponds to a sustainability indicator.

Each indicator value is derived using one of the following approaches:

• Empirical data from published studies and reports

• Averaged values from multiple documented case studies

• Standardized scoring for qualitative parameters

This structured dataset enables reproducibility of the normalization and aggregation process.

2.7 B dataset development procedure

The dataset used in this study was developed through a structured benchmarking approach based on multiple secondary data sources. Initially, published studies related to formwork performance, lifecycle assessment, construction productivity, and sustainability evaluation were screened from peer-reviewed journals, conference proceedings, technical reports, and manufacturer documentation. A total of approximately 22 documented studies and construction reports related to reinforced concrete construction and formwork technologies were reviewed. From these sources, quantitative and qualitative performance indicators associated with six formwork systems were extracted and categorized. Quantitative indicators such as construction cycle time, reuse cycles, material consumption, lifecycle cost, and waste generation were compiled using reported ranges and average values. Qualitative indicators such as ease of assembly and operational complexity were converted into normalized ordinal scores using a standardized rating framework. To improve consistency and reduce outlier influence, representative benchmark values were obtained through averaging and cross-validation across multiple literature sources. The resulting dataset forms a comparative decision matrix used for normalization, weighting, and sustainability evaluation.

The benchmark dataset represents synthesized performance information derived from approximately 15–25 reported construction applications involving residential towers, repetitive housing systems, and smart infrastructure developments where advanced formwork technologies such as aluminum and tunnel systems were implemented.

2.8 Data normalization and scoring

Normalization was performed in a manner that there is a meaningful comparison of different formwork systems. It was significant since the number of types of data formats and measuring units was so great. A linear normalization procedure transformed quantitative data into scores lacking any dimension. This was done to ensure that high ratings were always associated with high performance with regard to sustainability. A qualitative markers data were converted into numbers by a standardized ordinal scoring system. Among the methods that are widely identified by research in the context of sustainability evaluation in the field of civil engineering, there is one that allows integrating qualitative and quantitative indicators in a common evaluation framework (Gulghane, 2022). The strategy supports the integration of the two sets of indicators.

The sustainability indicators used in the research are measured using various unit and scales. As an example, time of construction cycle is determined in days, cost in monetary units, productivity in units of square meters/day and environmental impact in units of carbon emission or waste. Unless the values are brought to the same standard, it is not possible to directly aggregate these indicators. Hence, the original values of data were transformed by a minmax normalization technique resulting in dimensionless scores that lie between 0 and 1. Normalization was carried out using the following equation to give higher value to an indicator with high values (benefit criteria):

where: , normalized value of indicator j for alternative i; , actual value of indicator j for alternative i; , maximum value of indicator j among all alternatives; , minimum value of indicator j among all alternatives.

To normalize (indicators with lower value being good performance criteria) the following equation was used:

In this normalization process, all the values of the indicators are transformed to similar scores ranging between 0 and 1. A higher value will mean a higher sustainability performance.

The normalization process was performed using Equations (3) and (4) to convert the original criterion values into dimensionless values ranging from 0 to 1, ensuring comparability among different criteria.

2.9 Weight assignment of sustainability indicators

The short-term objectives of the project and the plans of the city concerning the smart city will ascertain the importance of each sustainability indicator. The weights of the indicators in the study were arrived at after long literature review on the topic of sustainable building practices, and the key requirements of a smart city infrastructure where expedited building, less waste, and efficient life cycle management were the key requirements. The conditions that needed to be associated with the environment and the functionality of the buildings were weighted considerably heavier as they have a significant impact on the duration of the city life (Gulghane et al., 2023a). The weighting approach attempted to make things less personal but yet maintaining the balance among the various things that influence sustainability. The weighting mechanism developed is very factual when making decisions pertaining to the urban development projects of such magnitude. Under a multi-criteria assessment system, various indicators do not play equal roles in the total sustainability rating. Thus, weighting coefficients were introduced to demonstrate the significance of importance of each sustainability indicator. The importance of the weighting structure used in the present study represents the priorities that can be usually seen in the infrastructure construction projects. The indicators were classified into three dimensions of sustainability and these are construction performance, economic performance as well as environmental performance. The role of construction indicators was relatively more important, as the efficiency of construction has a direct influence on the project duration and labor productivity. Economic indicators can be considered as financial viability of formwork systems and environmental indicators reflect ecological effects of using materials and waste production. The weighting coefficients were established by expert judgment and study of the past research studies on sustainable construction practices. The given weights meet the normalization requirement given in Equation 2, meaning that the total investment of all indicators is equal to one.

The choice of sustainability indicators is a very important aspect in the evaluation process since the correctness and pertinence of the final outcomes will be determined by the suitability of the selected indicators. In current paper, the selection of the sustainability indicators was made according to their relevance to the construction operations, quantitative data availability, and the possibility to express the three major aspects of sustainability namely; construction performance, economic feasibility and environmental impact. Construction performance indicators are the performance efficiency of the formwork systems. These measures reflect variables like construction cycle period, labor performance, re-use, and recovery and ease of assembling and de-assembling. These will have a direct impact on construction rates and time and these are very important factors when developing infrastructure. Economic indicators are the financial implications of the use of various form work systems. They are initial procurement cost, lifecycle cost, maintenance cost, and labor cost on installation and dismantling activities. Environmental indicators are those environmental effects of the materials and processes of the formwork systems. Such indicators encompass the material usage, wastes produced in the process of construction, carbon emissions as embodied, and the ability of the formwork materials to be recycled. These signs are indications of the growing focus on the consumption of resources and the lack of environmental impact in the development of infrastructure, which is sustainable. To improve methodological rigor, the weighting scheme was developed using a semi-systematic approach. Initially, sustainability indicators were ranked based on their frequency of importance and relevance reported in prior literature on construction sustainability and smart city infrastructure. These rankings were then normalized to derive relative weights. This approach reduces subjectivity and ensures that the weighting structure reflects established research trends and practical project priorities. To improve methodological rigor and reduce subjectivity in weight assignment, the Analytic Hierarchy Process (AHP) was incorporated into the weighting framework. Pairwise comparisons were performed for the three primary sustainability dimensions: construction performance, environmental performance, and economic performance.

The pairwise comparison process was guided by the relative importance of indicators reported in previous sustainability assessment studies, lifecycle construction management principles, and smart city infrastructure priorities. The normalized eigenvector method was used to derive final criterion weights. The resulting weights indicate that construction performance (0.42) is the most influential criterion, followed by environmental performance (0.33) and economic performance (0.25). The consistency ratio (CR) was calculated as 0.06, which is below the acceptable threshold of 0.10, confirming acceptable consistency in the pairwise judgments (see Table 1).

2.10 Criteria selection and weight assignment

Each criterion and sub-criterion is assigned weights that are premised on the synthesis of literature and practical applicability of the smart city infrastructure projects. The major dimensions of sustainability considered in the construction are construction performance, environmental impact, and economic efficiency, with each of them being measured by specific indicators. The parameters of the greatest weight are cycle time reduction and material use, and lifecycle costs since they can influence project efficiency, environmental sustainability, and long-term economic feasibility to the largest extent. The weighting model maintains the equilibrium between all three pillars of sustainability without being overly focused on any of the dimensions. Moreover, sensitivity analysis was used to test the adopted weights to make sure that changes in weight distribution do not materially affect ranking of alternatives and hence validate the soundness and dependability of the evaluation framework.

2.11 Calculation of percentage improvement

The quantitative enhancements presented in this paper are the relative performance variation of the MIVAN system formwork and the conventional system formwork system against the sustainability indicators that are selected. Such improvements are also computed based on percentage change analysis which determines the percentage change in performance of one construction system against the baseline system.

The percentage improvement is calculated using the following relationship by each sustainability indicator:

where: Value MIVAN: This is the measure of the performance of the MIVAN formwork system on a specific indicator. Value- Conventional is the performance value of the conventional formwork system. This expression enables the research to estimate the percentage increase in efficiency that would be obtained by the use of the MIVAN construction technology. When the indicators are of the type where low values are a sign of better performance, e.g., construction time, material waste, or consumed resources, the percentage of improvement is calculated by inverting the numerator to ensure a similar interpretation of positive improvement.

Based on this computational process, the indicators of the construction cycle time, labor productivity, material utilization efficiency, and waste generation are compared between the two construction systems to get the percentages of improvement reported in the results section.

2.12 Comparative evaluation method

Our approach at examining formwork systems on more than a single criterion was using a weighted aggregation technique, a widely used approach to studying sustainability in civil engineering research. This is one of the ways you can integrate a large number of performance indicators into a single index. This facilitates the fair comparison of the various types of formwork systems. We then determined the performance of each formwork system on all tests of which we could identify its sustainability. Others were such issues as the environmental impact of the project, the financial good it was going to bring and the overall functionality. The standardization of the raw data of each indicator (Gulghane et al., 2025) removed the differences in sizes and ensured that all indicators were rated similarly. After normalizing the indicators, we gave them a weight depending on their usefulness in smart city infrastructure projects. We have multiplied the normalized values of each indicator with their weights to obtain the weighted performance scores of each formwork system. The weighted score of all categories was summed up to obtain the total sustainability performance index of each choice of formwork. The score helps you to determine the performance of something in regard to the environment (Gulghane et al., 2023b). It is the way people rate the system of the formwork in the overall manner. Using the evaluation method, you can clearly see the impact of every formwork system on various ways to make sure they are more eco-friendly. This assists individuals in coming to know what is good and bad about both systems (see Table 2).

2.13 Sensitivity analysis

The review involved a sensitivity analysis of the results to determine how robust and sound the results were, when comparing them. We varied the weights of certain formwork systems to determine how it varied their total environmental score. This was due to the fact that people would have manipulated the weights of the indicators depending on their personal feelings. This approach rearranged the sequence of certain steps in sustainability, whereas the steps that were significant remained the same. The modifications were rational and were in accordance with the already existing rules. The research considers the variation of the rankings of the formwork systems under varying weights to ensure that the result is accurate. It also examines things that bear a significant influence on the effectiveness of sustainability programs. Our concerns were more about such aspects as the volume of waste we leave, rate of growth, and frequency of replenishing a product. All these are significantly important toward smarter cities. The sensitivity analysis indicates that the assessment structure is robust as the results do not vary significantly with the variation of the weights. This is a crucial step in the decision-support systems that should be applied in real-life projects since it helps to make the research more realistic and the approaches applied easier to comprehend. A sensitivity analysis was conducted in order to determine the strength of the sustainability evaluation framework. Sensitivity analysis is used to study the impact of change of the weights of indicators on the end result sustainability ranking of formwork systems. In the present work, the weights applied to the sustainability indicators were manipulated within a given range and the normalization constraint that was set in Equation 2 was kept. Each of the weighting scenarios was re-calculated to obtain the sustainability indices based on the weighted aggregation model indicated in Equation 1: The sensitivity analysis results also reveal that the order of the most effective formwork systems is not going to change when indicator weights change moderately. This proves the validity of the suggested evaluation framework and proves that it is appropriate when it comes to making a decision in the construction of sustainable infrastructure. To quantitatively evaluate robustness, the stability of rankings was assessed using Spearman’s rank correlation coefficient between the base case and modified weighting scenarios. The correlation values consistently exceeded 0.90, indicating a strong agreement between rankings and confirming that the model is not highly sensitive to moderate variations in weights.

2.14 A comparative analysis using TOPSIS

To validate the robustness of the weighted aggregation method, a comparative analysis was performed using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The same normalized dataset and weighting structure were used to compute the relative closeness of each formwork system to the ideal solution. The TOPSIS results showed a ranking pattern consistent with the weighted aggregate method, particularly for the top-performing alternatives such as aluminum and tunnel formwork systems. Minor variations were observed among intermediate alternatives; however, no significant rank reversal occurred among the best and worst performing systems. This consistency confirms that the findings of the study are not dependent on a single evaluation method and demonstrates the robustness and reliability of the proposed sustainability assessment framework.

2.15 Validation and applicability of the framework

The validity of the proposed assessment procedure was evaluated by comparing its findings with the known performance standards reported in the previous studies of the modern formwork systems and the traditional methods of construction. It is indicated by the fact that the present findings are consistent with the prior studies that the procedure can be considered both valid and applicable to the real-life context. The findings are a strong reinforcement of the notion that the contemporary formwork methods simplify the reuse of materials, accelerate the construction, and significantly decrease the amount of waste in the form of materials. Assessment system involves real data in comparing the results with known construction characteristics to demonstrate how buildings perform in reality. The most amazing thing about the framework is that you have an opportunity to modify it according to your needs. You can even make it even more by altering the sustainability measures, weighting schemes and the priority of the assessment. Its effectiveness has been well-tested. The structure is adjustable to the requirements of each project, the manner buildings are constructed in other locations, and the objectives of sustainability that evolve over time. The framework is applicable in much of smart city infrastructure projects in the public and the private sector. These projects may be small such as apartment buildings or big such as big developments. The proposed approach would assist engineers, planners and policymakers to select the appropriate formwork systems and at the same time ensure that they construct the environmentally friendly way. This provides individuals planning sustainable buildings with valuable information which is useful to them. In addition, validation is supported through sensitivity analysis and benchmarking against multiple published studies rather than reliance on a single comparative reference, thereby improving robustness and generalizability. Validation of the proposed framework was performed through three complementary approaches. First, the sustainability rankings were benchmarked against trends consistently reported in previous studies on modern formwork systems. Second, comparative analysis using the TOPSIS method was conducted to verify ranking consistency across alternative MCDM techniques. Third, sensitivity analysis involving ±20% variation in indicator weights was performed to evaluate ranking stability. The results demonstrated strong agreement between methods and minimal ranking variation, thereby confirming the robustness and reliability of the proposed framework.

2.16 Computational framework for sustainability evaluation

The sustainability assessment procedure adopted a methodical calculation model that comprised of a number of consecutive processes. Firstly, the sustainability indicators to be used were identified through literature review and industry practices. Afterwards, the performance data on the six formwork systems were obtained through the technical reports, research publications and manufacturer specifications. The data gathered in the next phase were categorized into benefit criteria and cost criteria based upon the presence of higher or lower values of better performance. The minmax normalization equations above were then used to normalize the data values. Normalization was followed by application of weighting coefficients to each indicator to show the relative values of the indicators in the sustainability evaluation. The value of indicators (normalized) was multiplied with respective weights and was summed up by applying Equation 1 to achieve sustainability index of each formwork system. Lastly, the sustainability indices were computed and the formwork systems were ranked based on their sustainability overall performance. To ensure reproducibility, all normalization equations, weighting structures, indicator definitions, and benchmark dataset values are explicitly provided in the manuscript and Appendix A. The proposed framework can therefore be replicated or adapted for other infrastructure projects by modifying indicator weights or input performance values.

2.17 Operationalization of sustainability indicators

In order to have a systematic and reproducible appraisal, the sustainability dimensions determined in this study construction performance, environmental impact, and economic performance- are operationalized using measurable indicators. The cycle time, ease of assembly, and reusability represent the construction performance and are used as a representation of project efficiency and execution speed. The measures of material consumption, waste production and carbon impact are used to calculate environmental performance based on resource consumption and environmental cost. Initial cost, lifecycle cost and maintenance or replacement cost are the economic performance measures that assist in a thorough evaluation of financial feasibility; across the time span of the project. Each indicator is scaled to standard scale and weighted aggregated using weighted aggregation approach to make them comparable and consistent across the various formwork systems (see Table 3).

The proposed methodology is grounded in the principles of multi-criteria decision-making and lifecycle sustainability assessment, while emphasizing computational simplicity and practical applicability. This positions the framework as a bridge between theoretical evaluation models and implementation-oriented construction decision-making.

3 Results and discussion

The general sustainability performance graph indicates the combination of sustainability index of every formwork system. This is achieved through a weighted summation of the parameters of the environmental, economical, and construction performance. This index incorporates a high number of various performance metrics and summarized them into one figure thus it is more efficient when it comes to assessing sustainability. Formwork solutions are increasingly in accordance with the principles of sustainability as the infrastructure of smart cities is constructed. This is evidenced by the fact that the sustainability rating of wood and tunnel formwork is gradually increasing. Conventional formwork systems comprising of steel and wood receive lower composite scores owing to the fact that they are inefficient with materials, inefficient in the production process and re-usability. However, they are better today, as they are more resistant, flexible and of the same quality and thus the current systems of formwork are more efficient (see Figure 1).

Figure 1

To further validate the robustness of the proposed weighted aggregation method, a comparative analysis was conducted using the TOPSIS method. The sustainability rankings obtained from both methods exhibit a high degree of consistency, particularly for the top-performing systems such as tunnel and aluminum formwork. Minor variations are observed among intermediate alternatives; however, no significant rank reversal occurs. This confirms that the results are not dependent on a single evaluation technique and enhances the reliability of the proposed framework. The superior performance of aluminum and tunnel formwork systems can be attributed to their high reusability, standardized modular design, and compatibility with mechanized construction processes. Unlike timber formwork, which deteriorates rapidly and requires frequent replacement, these systems enable a large number of reuse cycles, significantly reducing per-cycle material consumption and lifecycle cost. Additionally, the integration of wall and slab casting in tunnel formwork minimizes construction joints and accelerates project timelines, which directly enhances both construction and economic performance. This demonstrates that sustainability improvements are primarily driven by efficiency in material utilization and process optimization rather than only material type. The superior sustainability performance of aluminum and tunnel formwork systems can be attributed to their high reusability, standardized modular configuration, and compatibility with industrialized construction practices. Unlike conventional timber systems, which experience rapid deterioration and require frequent replacement, advanced formwork systems support a significantly higher number of reuse cycles, thereby reducing per-cycle material consumption and lifecycle cost. In addition, tunnel and aluminum systems facilitate faster construction through integrated wall–slab casting and reduced on-site assembly complexity. These findings indicate that sustainability improvements are primarily driven by process efficiency, material optimization, and lifecycle performance rather than material selection alone.

As illustrated in Figure 2, both evaluation methods produce nearly identical ranking patterns, with tunnel and aluminum formwork consistently achieving the highest sustainability scores. The alignment between the two methods demonstrates that the proposed weighted aggregation approach provides reliable results comparable to established multi-criteria decision-making techniques. This strengthens confidence in the applicability of the framework for real-world decision-making in smart city infrastructure projects.

Figure 2

As this graph indicates, when the technology of formwork systems is improved, the sustainability outcomes are better, particularly in large, repetitive projects, which require being constructed in a short period of time. Replacement of old formwork system with newer one is a definite trend. This indicates that sustainability performance is associated with better technology. Timber formwork is not the most sustainable one as it wastes numerous materials, can be reused only a few times, and becomes more dependent on the people. There are few disadvantages associated with steel formwork like it requires huge amounts of energy and it is difficult to manipulate, however, it improves regarding its longevity and reuse. The best in terms of sustainability is aluminum and tunnel formwork systems. This is due to the fact that they perform excellently in all aspects. Both of the systems appear to be effective in smart city infrastructural projects where one has to construct a significant number of housing units with identical designs and structural elements. This is the reason why they are so alike making it appear that they are both suitable to sustainable building. This is a trend to demonstrate that cost is not the only thing we have to consider when we select formwork, but the entire picture of sustainability. The improved environmental performance of advanced formwork systems is strongly associated with enhanced durability and reuse potential. Timber formwork systems generate higher material waste and require repeated replacement, leading to greater resource consumption over the project lifecycle. In contrast, aluminum, modular, and tunnel formwork systems reduce overall environmental burden through extended service life and lower waste generation. However, it is important to recognize that materials such as aluminum and steel possess relatively high embodied energy during manufacturing. Consequently, the sustainability advantages of these systems become more significant in projects involving repetitive construction cycles and large-scale implementation (see Figure 3).

Figure 3

The environmental sustainability performance measures included in the graph due to their direct correlation with the resource consumption and environmental impact are material efficiency, recycling rates and trash production. During the construction, formwork material type, system durability and design efficiency influence the environmental performance. This is shown by the graph. The results underscore the role of reducing the usage of raw materials and constructing waste through several occurrences of use in the process of having environmental sustainability in the formwork systems. The frequency of material replacement and disposal is highly reduced because of the designed design and extended service of modern formwork systems which makes the systems to be rated highly in terms of environmental mannerisms. Conversely, traditional formwork techniques lead to further wastage and indirect environmental impairment because they use materials with a short lifespan or those that are utilized once. The graph indicates the significance of making the right choice when adopting the formwork to reduce the effects of the smart city infrastructure projects to the environment. The observed improvement in environmental performance from timber to advanced formwork systems is primarily due to differences in material durability and reuse potential. Timber formwork contributes to higher environmental burden due to single-use or low reuse cycles and associated waste generation. In contrast, aluminum and modular systems significantly reduce environmental impact through extended service life and recyclability. However, it is important to note that materials such as steel and aluminum have higher embodied energy during production, which may offset some environmental benefits in projects with limited reuse cycles. This highlights that environmental sustainability is highly dependent on project scale and repetition level, rather than material choice alone.

It is also evident that there is an incremental and unwavering upward trend in the environmental performance between the use of lumber and other advanced forms of formwork. Timber formwork is the least environmentally-graded due to its short lifetime, susceptibility to damage, and it has high wastage. Steel formwork is a bit more improved since it has a higher possibility of being recycled, although it is still a threat to the environment due to the energy used to manufacture and transport. The top performers of these characteristics, with their high reusability and little rate of material loss, are aluminum and tunnel formwork, which is then succeeded by plastic, modular, and aluminum systems. The trend line is going up, indicating that the main factor that is making the formwork systems to be eco-friendly is reusability. This discovery is of specific importance in smart city projects where high-reuse formwork technologies have proven to be particularly beneficial because of massive repeated building. A significant trade-off identified in the analysis relates to the relationship between initial investment and long-term lifecycle performance. Advanced systems such as aluminum and tunnel formwork require substantially higher initial capital investment compared to conventional timber systems. Nevertheless, these systems achieve lower lifecycle cost through higher reuse cycles, reduced labor dependency, shorter construction duration, and lower maintenance requirements. This demonstrates that sustainability-oriented decision-making should not rely solely on initial construction cost, particularly in large-scale smart infrastructure projects where operational efficiency and reuse potential play a critical role (see Figure 4).

Figure 4

In addition to evaluating formwork systems based on their initial capital investment rate, other economic indicators of the lifetime economic performance, including productivity, labor efficiency, and cost per use are also evaluated, based on the economic performance graph. This strategy is compatible with sustainable building principles, which focus on long-term value creation rather than minimization of the costs in the short term. The graph indicates that the modern formwork is more economical in terms of construction since it is faster and can be utilized in repeated construction though at a higher cost in the initial stage. Conventional formwork such as lumber is not so economy-friendly as they require numerous labor to construct, require frequent replacement, and are rather expensive. Modern systems, however, are simpler to maintain since they construct and dismantle more quickly, require less labor and also, perform better. The graph indicates that in selecting formwork in smart city infrastructure projects, it is better to examine the entire lifecycle cost.

The economic performance has a distinct increasing trend in the replacement of older to newer formwork systems. Timber formwork also scores moderately due to its cost of acquisition which is cheap and high labor intensity. Its lifespan economy is however significantly lower due to its limited reuse capabilities. Durability and low productivity gains are some of the factors which lead to superior economic performance of steel and plastic formwork. Good economic sustainability of modular, aluminum, and tunnel formwork systems is based on high production rate, reduced labor requirement, and reduced building cycles. This is particularly so when it comes to smart cities projects that require strict deadlines and structures to be rebuilt (numerous times) that require modern formwork systems as the high initial costs are easily offset by the high lifetime economic benefits. This is an indication that the entire project lifespan must be taken into account during the evaluation of economic sustainability in the construction industry. A critical observation from the economic analysis is the trade-off between high initial investment and long-term cost efficiency. Advanced formwork systems such as aluminum and tunnel formwork require significantly higher upfront costs compared to timber systems. However, their high reuse potential, reduced labor requirements, and faster construction cycles result in lower lifecycle costs. This indicates that decision-making based solely on initial cost can lead to suboptimal outcomes, particularly in large-scale smart city projects. The findings reinforce the importance of adopting a lifecycle cost perspective in evaluating construction technologies. The enhanced construction performance of modern formwork systems is primarily associated with standardization, prefabrication, and reduced dependency on manual craftsmanship. Tunnel and aluminum systems utilize modular prefabricated components that improve dimensional accuracy and minimize on-site variability. This results in shorter construction cycles, improved safety conditions, and reduced probability of construction errors. In contrast, conventional formwork systems require significant manual adjustments and exhibit greater variability in construction quality and productivity (see Figure 5).

Figure 5

The construction performance graph depicts indicators of the operations of the project in terms of speed of work, safety, ease of handling and the quality of work. These requirements are far more critical in the case of the smart city infrastructure projects, where the quality control, safety of workers and deadlines are all very critical. The technology of modern formwork has made construction to be very efficient and reliable as you see in the graph. The modern formwork systems are effective all through the construction process since they utilize the standardized components, are manufactured to precise requirements and suit mechanized construction techniques. These characteristics make the construction cycles more efficient, provide surfaces with a more glossy look, and help to preserve work safety. Conventional formwork operations, however, are lengthy and possess numerous quality control issues since they rely on individuals and their capabilities.

Among all the factors that influence sustainability, construction performance has enhanced the best. The worst option would be timber formwork since it is of low quality, requires skilled labor, and is more time-consuming in installation. Steel formwork makes them more consistent, though it is heavy and difficult to move, which might complicate the safety and efficiency of things. The three types of formwork, which include modular, aluminum, and tunnel, are very suitable in the construction of sites. However, it is the easiest method of constructing walls and slabs and is quick and frequent when it comes to constructing a tunnel formwork. The fact that the demand has increased so rapidly indicates that the two most essential elements that the development of smart city infrastructures should be sustainable are speed of construction and the degree of quality control involved. These findings indicate the relevance of CPIs to a holistic evaluation of sustainability. The superior construction performance of modern formwork systems is largely driven by standardization and reduced dependency on skilled labor. Systems such as tunnel and aluminum formwork are designed for repetitive use with prefabricated components, which minimizes on-site variability and human error. This leads to faster cycle times, improved safety conditions, and higher quality finishes. In contrast, traditional formwork systems rely heavily on manual labor and site-specific adjustments, which increases variability, construction time, and potential safety risks. Therefore, improvements in construction performance are closely linked to industrialization and process control in construction practices. The overall sustainability assessment demonstrates that high-performing systems achieve balanced optimization across environmental, economic, and operational dimensions rather than excelling in a single parameter. Although conventional timber systems may exhibit lower initial cost, their limited reuse potential and higher material wastage reduce their long-term sustainability performance. Conversely, aluminum and tunnel formwork systems maintain strong performance across multiple criteria, indicating that integrated lifecycle efficiency is a key determinant of sustainable construction technology selection (see Figure 6).

Figure 6

To enable the comparison of the sustainability of the various formwork systems, we will use a composite radar graph to make comparisons across four significant axes: economic sustainability, environmental sustainability, construction performance, and overall sustainability index. The axis displays a normalized score ranging between 0 and 1, and it is easier to compare various formwork options. The enclosed space of every formwork system represents part of how much the system influences the environment. The smaller size results in poorer performance and therefore less balance. The radar map indicates that the traditional forms of work such as wood and steel occupy less regular and somewhat smaller spaces which indicates that their functionality is constrained in most aspects of sustainability. Aluminum and tunnel formwork are two examples of contemporary formwork systems that are notable due to the wide profile and the uniform distribution of the profiles and they work well on all the considered parameters. The radar visualization is very effective in demonstrating how complex sustainability evaluation is, and it is difficult to achieve that using only tables of data. This is an upward trend that has been seen since old-fashioned to modern formwork systems. Although timber formwork has average economic ratings in this case since it is cheap to purchase, it performs poorly in the environment and construction performance since it has a small radar area. In spite of modern developments in the economic and building field, steel formwork continues to be disadvantaged by environmental factors due to its high embodied energy and handling challenges. The plastic and modular formwork systems have a mid-range performance, which indicates that the systems under consideration are more efficient than the conventional systems in construction, waste generation, and reuse. As indicated in their radar profiles, they are in transition, where their conventional formwork technologies are being replaced with the ones that have been optimized fully. Radar graph comprises primarily of aluminum and tunnel formwork systems in terms of size and symmetry. This demonstrates that the number of trade-offs between the sustainability of the environmental, economic, and building metrics was minimal, and the sustainability performance was extremely high. Superiorly, as an illustration, one can consider tunnel formwork, which is highly environmental-friendliness and can be employed to construct big and repeated smart city infrastructure. It appears that both the aluminum and tunnel formwork technologies are the established and eco-friendly technologies to use in the modern city construction, as their profiles are very similar. It is additionally noted in the radar graph that the building performance and environmental sustainability are the most significant factors. The reason behind this is the fact that these axes depict more distinct differences as compared to others. This observation corresponds to the objectives of a smart city, which are the rapid construction, the optimal use of resources, and the maintenance of high quality. The radar analysis highlights that sustainability performance is not determined by a single parameter but by a balanced interaction of environmental, economic, and construction factors. While timber formwork performs moderately in terms of initial cost, its poor environmental and construction performance limits its overall sustainability. Conversely, aluminum and tunnel systems demonstrate a well-balanced profile, indicating minimal trade-offs between different sustainability dimensions. This suggests that future construction technologies should aim for integrated performance optimization rather than isolated improvements. The TOPSIS results indicate that tunnel and aluminum formwork systems exhibit the highest closeness to the ideal solution, with scores of 0.92 and 0.88, respectively. Traditional systems such as timber formwork show significantly lower performance (0.31), confirming their limited sustainability. The ranking pattern is consistent with the weighted aggregation method, demonstrating strong methodological agreement (see Figure 7).

Figure 7

The sensitivity analysis graph 7 proves the strength of the suggested sustainability evaluation model by analyzing the influence of the changes in the weights of indicators (± 20%). The findings have established significant model stability as it is clear that the aluminum system and tunnel formwork systems have always retained their first positions in terms of ranking by the various scenarios. The almost parallel trend lines indicate that the alteration of weighting assumptions does not have a major impact on the overall result. There are slight differences in the scores, but they do not result in rank reversal, particularly among the most performing systems. This proves the fact that the model is not too sensitive to subjective inputs and can be successfully used to make decisions. The soundness of the approach exhibited in this analysis validates the reliability of the weighted aggregate approach as an effective and reliable tool of sustainability evaluation.

The findings of this study are generally consistent with previous research that highlights the advantages of modern formwork systems in terms of productivity and lifecycle efficiency. For instance, prior studies have reported significant reductions in construction time and material waste when using aluminum and tunnel formwork systems. However, some studies emphasize the high embodied energy and cost of advanced materials, suggesting that their sustainability benefits are context-dependent. The present study supports this perspective by demonstrating that the advantages of modern formwork systems become more pronounced in large-scale and repetitive construction projects, which are typical of smart city developments. This highlights the importance of aligning technology selection with project characteristics. From a theoretical perspective, the findings reinforce the importance of integrating lifecycle thinking and operational efficiency into sustainability assessment models. The results demonstrate that sustainability performance is not solely dependent on material properties but is significantly influenced by process efficiency, reuse potential, and system standardization. This aligns with emerging trends in construction management research that emphasize industrialized construction and resource optimization. Furthermore, the study highlights the relevance of simplified decision-making frameworks in bridging the gap between theoretical sustainability models and practical implementation in smart city infrastructure projects.

4 Conclusion

This study compares the traditional and modern sustainable formwork methods of smart city infrastructural projects. This is a mathematical procedure that we employ to integrate environmental, economic, as well as construction performance criterion to assist you in selecting a formwork system. The findings indicate that formwork technology has a significant role to play in the construction of long lasting cities particularly in projects that are not long time, recurrent and resource efficient. The duration of the old and new formwork systems in the long run is tested more than the previous ones. There was an increment in steel formwork of 0.55 which translates to a longer durability and a reduced difficulty in the re-use of the formwork. Nevertheless, wood formwork received the least rating on its environmental friendliness (0.45). More advanced systems that are more sustainable comprise modular (≈0.72), aluminum (≈0.85), and tunnel formwork (≈0.88). This tunnel system takes up 90%–95% more time than the normal wood systems. The differences in the way the aluminum and tunnel formwork approaches operate testify to the fact that the two approaches are highly technical and can be employed as part of a smart city project. The findings demonstrate that being able to reuse and make less trash are the most significant factors to the environment. Wood formwork scores a negative score of bad (about 0.40) as it consumes a lot of materials and can only be used multiple times. There was an increase of 0.50 in steel formwork, 0.70 to 0.78 in plastic and modular systems. To ensure environmental sustainability, the materials of aluminum and tunnel formwork scored 0.88 and 0.90, respectively. It is superior to wood formwork by over 120% better. These findings support the concept of smart city sustainability by demonstrating that because of formwork solutions that can be re-used and re-purposed, the construction level of materials and waste is reduced. An economic performance study of lifetime performance indicates that there is no relationship between the price and quality of formwork. Timber formwork is cheap initially but it cannot last long (approximately by 0.50) as it requires frequent replacement, its manufacture is not easy and time consuming. The steel and plastic formwork only work 0.60%–0.65% of the time during the time of their life. Modular, aluminum and tunnel formwork systems have high ratings of economic sustainability (approximately 0.75–0.85). This implies that they are more effective and less expensive to operate. Newer formwork technologies consume 30%–40% less during their entire life as compared to older formwork technologies. This is positive to large scale smart city projects that will be long-term. We went through the systems and found out that the greatest concern of the long-term well-being of the building was the housebuilding quality. Timber formwork scores the lowest in the performance of construction (≈0.42) as it is hazardous, requires skilled labor, and it is not always evident how good it is. Although there was an improvement in steel formwork (0.58), complexity was difficult to cope with. Tunnel formwork receives the highest rating (approximately 0.80–0.92) of all systems, such as modular systems, aluminum, and so on. This is due to the fact that it produces walls and slabs in a single piece and within a very short time. The construction of the tunnel formwork is over 110% superior to the construction of wood, and this indicates the significance of the rapid, precise, and safe construction of infrastructure of smart cities. The sensitivity research indicated that evaluation was performed in the proper manner. More recent systems of formwork generally performed better than older ones, and loads of the indicators did not vary the hierarchy of systems much. The extent to which something can be reused, the rate at which it can be constructed and the amount of waste generated is all relevant to the extent to which something is sustainable. These are the initial steps that you should consider whenever making decisions concerning building environmentally friendly buildings.

Even though the current paper lacks single site case study, the input parameters and performance measures are calculated based on the commonly reported construction practices and confirmed by the comparative benchmarking. The recorded enhancements in the cycle time, material reuse, and cost of life are in line with the reported performance of the modern formwork systems in the large construction projects. Thus, the suggested framework gives a stable ground on which preliminary decisions could be made, and it can be easily customized to the evaluation of projects. A comparative evaluation using the TOPSIS method further validated the ranking results obtained from the weighted aggregation approach. The consistency between both methods strengthens confidence in the findings and indicates that the sustainability performance trends are method-independent. The theoretical contribution of this study lies in the development of a simplified yet robust sustainability evaluation framework that integrates environmental, economic, and construction performance dimensions. Unlike traditional MCDM approaches, the proposed model emphasizes transparency, computational efficiency, and practical applicability, making it suitable for real-world infrastructure decision-making. The study also contributes to construction management literature by demonstrating the importance of lifecycle-oriented evaluation and aligns with smart city development goals by promoting efficient and scalable construction technologies.

The researchers found out that aluminum- and tunnel formwork systems are eco-friendly, cheaper and more effective in building compared to wood and steel systems. Our trends also point strongly to the notion that in the infrastructure development projects of smart cities, evaluation frameworks that are based on sustainability and the entire lifecycle must be employed. Placing long-term sustainability over short term costs might enable engineers and policymakers to make the construction more efficient, less damaging to the environment, and more cost-effective. The assessment framework would assist us in making decisions, designing environmentally friendly buildings, and gaining new insights as to how to create smart city infrastructure. The study points out that the sustainable, efficient, and strong urban environment should be developed with the help of evidence-based policies and the widespread use of innovative and sophisticated formwork technologies.

4.1 Limitations and future research directions

While the proposed sustainability assessment framework provides a structured and practical approach for evaluating formwork systems, several limitations should be acknowledged. The study is based on a benchmark dataset derived from multiple literature sources, technical reports, and industry practices, rather than a single real-world case study. Although this approach enhances generalizability, it may not fully capture project-specific variations such as site conditions, labor availability, and regional cost differences. Future research could incorporate project-level empirical validation to improve contextual accuracy. The analysis relies on a combination of empirical, derived, and assumption-based data, particularly for qualitative indicators such as ease of assembly. While standardized scoring methods were applied, such transformations may introduce interpretation bias. Further studies may benefit from integrating field-based measurements or real-time construction data to enhance data precision. Although the weighting scheme was strengthened using the Analytic Hierarchy Process (AHP) and validated through sensitivity analysis, the assignment of weights inherently involves a degree of subjectivity. Variations in stakeholder priorities or project objectives may lead to different weighting structures and, consequently, different ranking outcomes. Future work could explore stakeholder-driven or dynamic weighting approaches to address this limitation. The proposed framework is primarily suited for large-scale and repetitive construction projects, such as those found in smart city infrastructure development. Its applicability to small-scale or highly customized construction projects may be limited, as the advantages of advanced formwork systems are more pronounced in high-repetition scenarios. Finally, the study focuses on a selected set of sustainability indicators and formwork systems. While these were chosen based on relevance and data availability, additional factors such as social sustainability, safety performance metrics, and digital construction integration (e.g., BIM-based planning) could further enhance the comprehensiveness of the assessment framework. Despite these limitations, the study provides a robust foundation for comparative sustainability evaluation and offers a flexible framework that can be refined and extended in future research.

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