Development and Application of Building Circularity Assessment Tool Based on Building Information Modeling

Abstract

The transition to a circular economy in Taiwan’s building sector is constrained by the lack of standardized, quantitative assessment methods. To address this, this study establishes a novel, localized theoretical framework integrating the Material Circularity Index (MCI) and the Madaster system, implemented via an automated Building Information Modeling (BIM) computational tool. The framework structures assessment across three life cycle stages and four hierarchical levels. Its feasibility was validated through the Wafer Works Erlin Plant project. The results indicate that the BIM-based method effectively tracks material flows, demonstrating that structural design strategies and certified Green Building Materials significantly enhance circularity performance. This research provides a scalable, scientific instrument for quantitative evaluation, offering actionable insights to advance evidence-based sustainable design in the local construction industry.

1. Motivation and Purpose

The construction industry generates substantial construction and demolition waste across the entire building life cycle and exerts significant environmental pressure due to its reliance on a linear economic model. Although it accounts for approximately 30% of global natural resource consumption, it produces nearly 40% of the world’s solid waste [1], underscoring the urgent need for more resource-efficient strategies. The circular economy (CE), which advocates systemic regeneration through design-oriented approaches, is closely aligned with the United Nations Sustainable Development Goals. To effectively monitor and evaluate CE implementation in the built environment, “circularity” has emerged as a core indicator of performance. This study aims to establish a theoretical framework for building circularity assessment that combines scientific measurement with international methodologies while remaining adaptable to Taiwan’s construction context. The proposed framework develops operational calculation formulas and computational tools, emphasizing integration with Building Information Modeling (BIM) technology to enable dynamic, automated calculations. Feasibility will be examined through applications to actual construction projects, thereby bridging theoretical development with practical validation. By introducing a BIM-based, scientifically grounded assessment model, this study seeks to provide a robust tool for Taiwan’s construction industry to advance resource reuse, enhance material efficiency, and contribute to long-term carbon neutrality goals.

2. Literature Review

The Circularity Indicator (CI) has emerged as an important tool to assess, monitor, and communicate circular economy (CE) performance by quantifying the extent of resource recovery and the overall circularity of systems [2]. Its primary function is to support the transition from a linear economy to a circular economy by providing measurable data for decision-making and guiding the effective implementation of circular strategies. The seminal work Cradle to Cradle (2002) [3] challenged the cradle-to-grave industrial paradigm that threatened both human and environmental health. Subsequently, Towards a Circular Economy (2013) [4] emphasized abandoning the “take–make–discard” model in favor of renewable energy use, waste elimination, and design-oriented regeneration. Since then, research on CE and its applications has expanded significantly. For example, scientometric analysis of 1117 articles indexed in Web of Science demonstrates a rapid increase in publications since 2018, reflecting global policy emphasis and scholarly engagement [1]. (Figure 1)

A key milestone was the release of the Material Circularity Indicator (MCI) in 2015 by the Ellen MacArthur Foundation, which provided a foundation for the quantitative analysis of material cycles and inspired the development of differentiated indicators across industries. In the building sector, Rahla et al. [5] highlighted in 2019 the inherent complexity of assessing circularity in construction, citing challenges such as inconsistent definitions, data limitations, and the lack of standardized tools. More comprehensive frameworks for building circularity assessment were proposed in 2021, including those by Cottafava et al. [6] and Zhang et al. [7], which integrated material flows, embodied impacts, and design aspects into multi-level evaluation systems.

Parallel developments have been observed in Taiwan, where early studies focused primarily on material-level circularity but have increasingly advanced toward whole-building assessment. Since 2021, Taiwanese scholars have explored integrating CE principles into architectural planning [8], promoting circular material strategies [9], and developing tools that combine Building Information Modeling (BIM) and Geographic Information Systems (GIS) for urban-scale simulations [10]. More recently, efforts have focused on localizing the Building Circularity Indicator (BCI) to reflect Taiwan’s construction practices and regulatory environment [11,12,13]. These developments illustrate a growing recognition of the importance of context-specific frameworks and computational tools for advancing CE in the built environment (

Table 1. Literature summary and analysis.

Author	Title	Abstract	Keywords
Rahla, K M. et al. 2019 [5]	Obstacles and barriers for measuring building’s circularity	The development of circular economy (CE) assessment tools for buildings encounters several major obstacles: (1) the proliferation of CE definitions, which creates inconsistencies in interpretation and application; (2) the inherent complexity of buildings, encompassing diverse materials, components, and life-cycle stages; (3) the prevalence of irrelevant, outdated, or arbitrarily defined indicators that undermine reliability; (4) the absence of adequate tools and databases for systematic data collection and management; (5) the neglect of social dimensions, resulting in incomplete assessments; and (6) ambiguities in weighting and scoring methods, which limit comparability and transparency. Overcoming these challenges is essential for establishing robust, comprehensive, and widely applicable CE assessment methodologies in the built environment.	Circular economy, Assessment tool
Cottafava, D. et al. 2021 [6]	Circularity indicator for residential buildings: Addressing the gap between embodied impacts and design aspects	This study proposes enhanced assessment methods for evaluating circularity in buildings, with a particular focus on sustainability challenges in the European Union (EU) built environment, especially regarding resource consumption and waste generation. Conventional circularity indicators primarily address raw material use, waste output, and product life span; however, they lack an integrated perspective that simultaneously considers material impacts at the macro level, supply chain processes at the meso level, and design strategies at the micro level. To address this gap, two novel indicators are introduced: (1) the Building Circularity Index (BCI) and (2) the Predicted Building Circularity Index (PBCI). Both indicators integrate material circularity, embodied energy, embodied carbon, and design for disassembly criteria, thereby providing a more comprehensive framework for assessing circular performance in the built environment.	Circular economy; Circularity indicator; Design for disassembly; Embodied carbon
Zhang, N. et al. 2021 [7]	Building Circularity Assessment in the Architecture, Engineering, and Construction Industry: A New Framework	This study introduces a new framework for assessing building circularity that integrates three key dimensions: (1) a material flow model, (2) a material passport, and (3) a building circularity calculation method. Within this framework, five indicators are proposed to capture critical aspects of circularity: (1) origin of input materials, (2) origin of materials in output, (3) efficiency of recycling processes, (4) realization of functional units, and (5) lifespan. By combining these dimensions and indicators, the framework provides a comprehensive foundation for advancing the implementation of circular economy principles in the architecture, engineering, and construction industry.	Building circularity assessment; material flow model; Material passport;
Gomis, K. et al. 2023 [1]	Scientometric Analysis of the Global Scientific Literature on Circularity Indicators in the Construction and Built Environment Sector	This study employs scientometric analysis to examine the academic literature on the circular economy (CE) and related indicators. Data were collected from the Web of Science database, covering the period from 1970 to the third quarter of 2022, resulting in a sample of 1117 articles. The analysis was conducted using VOSviewer software (version 1.6.17). The findings reveal a substantial increase in publications since 2018, largely driven by the United Nations Sustainable Development Goals (SDGs) and policy initiatives. Moreover, research themes have evolved over time, shifting from a predominant focus on technological and model-oriented approaches toward strategy development and the identification of barriers to CE implementation.	Circularity indicators; sustainable cities and communities; Built environment; VOSviewer
Anastasiades, K., et al. 2023 [14]	Circular Construction Indicator: Assessing Circularity in the Design, Construction, and End-of-Life Phase	This study proposes a Circular Construction Indicator (CCI) framework that encompasses three major stages of the construction process: (1) the design phase, (2) the construction phase, and (3) the end-of-life (EoL) phase. The framework evaluates the four principles of the circular economy (4R: reduce, reuse, recycle, and recovery). During the design phase, material scarcity is explicitly considered, and a structural assessment of material efficiency is conducted. A multi-level indicator system is introduced, covering the element, component, system, and construction levels. At the EoL stage, a time–quality degradation function is incorporated to predict material reusability. Collectively, this framework provides a comprehensive approach for integrating circular economy principles into the construction sector.	Circular economy; Circularity indicator; Construction phases; 4 Rs
Khadim, N. et al. 2023 [15]	Whole building circularity indicator: A circular economy assessment framework for promoting circularity and sustainability in buildings and construction	The Whole Building Circularity Index (WBCI) is developed by integrating the strengths of existing methodologies, including the VERBERNE Building Circularity Index (VBCI), the Material Circularity Index (MCI), and Flex 4.0, among others. Designed from a building life cycle perspective, the WBCI accounts for material flows from their point of origin through disposal or waste treatment. This comprehensive framework incorporates a broad range of key performance indicators and operates across multiple levels—material, element, system, and whole building. In this way, the WBCI enables the identification of best-performing circular economy strategies, thereby supporting more effective evaluation and implementation of circularity in the built environment.	Building circularity indicators, Circular economy, Circularity assessment, Sustainable buildings,
Incelli, F. et al. 2023 [16]	Circularity Indicators as a Design Tool for Design and Construction Strategies in Architecture	The fragmentation of circular design knowledge and the absence of a unified methodology remain major barriers to the adoption of circular practices in the built environment. This study underscores the importance of integrating structural connectivity and circularity strategies during the conceptual design phase and advocates for embedding circularity at all scales beyond the material microscale. In particular, it highlights the need for the early adoption of a cyclical scoring system for Design for Disassembly (DfD). Such a system should enable the evaluation of three fundamental DfD principles: (1) structural adaptability, (2) component modularity, and (3) physical interchangeability of parts. By addressing these aspects, the study provides a pathway for advancing systematic and scalable approaches to circular design.	design for disassembly; Building circularity indicator
Xie, S.X. et al. 2021 [10]	Combining BIM and GIS information to simulate the circularity and carbon emissions of building complexes	The purpose of this study is to enhance the assessment of urban sustainability by integrating building-level and city-scale data. To achieve this, architectural and urban information are combined through Building Information Modeling (BIM) and Geographic Information Systems (GIS). Based on this integration, an assessment tool is developed to simulate energy consumption, material circulation, and carbon emissions of building clusters within cities. The proposed approach provides a systematic method for evaluating the environmental impacts of the built environment and offers decision-makers a valuable tool to support the planning and implementation of circular economy and low-carbon urban strategies.	BIM, GIS, material circularity, low-carbon cities, circularity index, urban building energy simulation
H.-Ping Tserng, et al. 2021 [11]	The Key Strategies to Implement Circular Economy in Building Projects—A Case Study of Taiwan	The building industry exerts a substantial impact on global resource consumption and waste generation, underscoring the importance of adopting circular economy (CE) principles. This study compares Dutch and Taiwanese CE pilot projects through case studies and semi-structured interviews with Taiwanese stakeholders. Thirty key CE practices were identified and categorized according to the 5R principles—Rethink, Reduce, Reuse, Repair, and Recycle—as well as project phases. The results indicate that Dutch projects apply comprehensive strategies, such as design for disassembly and modular construction, whereas Taiwanese initiatives remain limited in scope and implementation. Based on these findings, recommendations are proposed to align CE practices with local project phases, thereby providing stakeholders with practical guidance to advance sustainable transformation in Taiwan’s building sector.	circular economy in construction, strategic implementation, 5R principles
Zhang, Y.C. et al. 2021 [12]	A preliminary discussion on establishing an assessment and certification system for circular architecture and construction in Taiwan (Part I)	Building on the Material Circularity Index proposed by the Ellen MacArthur Foundation and considering the specific characteristics and needs of Taiwan’s architecture and construction industry, this study develops an assessment and certification system for circular buildings in Taiwan. The framework emphasizes the establishment of differentiated circular strategies and objectives across the three main stages of the building life cycle: construction, use, and demolition. This approach provides a structured pathway to guide the implementation of circular economy principles in the Taiwanese built environment.	Material circularity index, circular building assessment system
Wang and Huang 2022 [13]	A study on the material circularity evaluation of components for circular building design	This study addresses the specific context of the domestic construction industry and establishes a streamlined formula to evaluate the circularity of building design components. The proposed method not only considers the Fraction of recycled materials incorporated into building products but also integrates domestic certification systems, including green building material labels (recycled and ecological), environmental labels, and resource recycling green product certifications. Building materials already certified as recycled in the domestic market are used as reference points. In practice, the framework enables designers to assess material selection by focusing on three major categories—structure, decoration, and landscape—where recycled materials are frequently applied. The fraction of recycled materials within these categories serves as the primary metric for evaluating the circularity of building component materials.	Building materials recycling rate, building materials bank, recycling rate

).

According to the literature, various building circularity index (BCI) models have been developed internationally. These models are generally derived from the Material Circularity Index (MCI), incorporating the strategic factors of the circular economy (R-strategies) to establish building circularity assessment methods. Their development is often supported by life cycle assessment (LCA), which defines system boundaries, building levels, and integrates design for disassembly (DfD) considerations into circularity calculations. Nevertheless, the models exhibit differences in strategies and implementation, reflecting variations in research objectives, data collection methods, local building characteristics, and contextual constraints. A summary of these models is provided as follows:

2.1. Development of Circularity Indicators

The Circularity Indicator (CI) has evolved from the Material Circularity Indicator (MCI) proposed by the Ellen MacArthur Foundation to more complex, building-specific models. While MCI provided a foundation for quantifying material flows (linear vs. circular), it primarily focused on product manufacturing. Subsequent frameworks like Madaster and CB’23 adapted these principles to the built environment by incorporating material passports and varying waste scenarios. However, differences remain in how these models handle “recycling efficiency” and specific R-strategies (Reuse, Repair, Recycle). For instance, while MCI includes refurbished materials, CB’23 focuses strictly on input/output classifications [7]. These inconsistencies highlight the need for a unified framework adaptable to local contexts.

2.2. System Boundaries and Life Cycle Assessment Context

Unlike traditional Life Cycle Assessment (LCA) which encompasses comprehensive environmental impacts, Building Circularity Indicators (BCI) specifically target material resource flows. Recent studies, such as Khadim’s BCI, argue for excluding raw material extraction (A1–A2) and operational energy/water use (B6–B7) from circularity scores, treating them as separate sustainability metrics. However, neglecting the construction and assembly phase (A5)—which accounts for significant waste—remains a limitation in some models like the Virgin Material Circularity Indicator. Therefore, a robust assessment must explicitly integrate the construction phase to capture assembly efficiency and waste reduction potential [15]. The system boundary of the Whole Building Circularity Index (WBCI) is illustrated by the blue thick box, marked on the building sustainability assessment standard EN 15978:2011 [17], in Figure 2.

2.3. The Role of Facility Management (FM) in Circularity

While the material flow model defines the potential circularity of components, the actual performance during the lengthy operational phase is heavily dependent on Facility Management (FM). The recent literature, particularly from the Australian context, has established a strong “FM-circularity nexus”. FM professionals play a decisive role in “closing the loop” by enforcing green procurement policies for replacement parts and implementing proactive maintenance strategies [18]. In the context of the Building Circularity Indicator (BCI), FM is the primary driver for maximizing the Utility Factor F(X) (as defined in Formula 6). By managing repair (B3), refurbishment (B5), and replacement (B4) cycles effectively, FM extends the actual service life (L) of building layers beyond the industry average (L_av), thereby directly influencing the comprehensive circularity score computed in this study’s framework.

2.4. Hierarchical Assessment and Design for Disassembly (DfD)

To address the complexity of buildings, scholars have moved towards a multi-level assessment approach, evaluating circularity across materials, elements, systems, and the whole building. This hierarchical structure relies heavily on design quality. Research indicates a causal link between early-stage design strategies—specifically Design for Disassembly (DfD)—and end-of-life circularity. By quantifying disassembly potential using factors such as connection type and accessibility, DfD serves as a crucial predictive indicator for material recovery, bridging the gap between design intent and actual circular performance [19,20,21].

2.5. Research Gaps and Synthesis

Despite the proliferation of circularity indicators, three critical gaps remain that hinder their effective adoption in Taiwan’s construction sector: 1. Lack of Contextual Localization: Prevalent international models (e.g., Madaster, MCI) are not adapted to Taiwan’s specific regulatory environment and material practices, such as the predominance of reinforced concrete. 2. Operational Complexity: The hierarchical nature of buildings—from materials to whole structures—makes manual calculation labor-intensive and error-prone. Current literature highlights a lack of standardized, automated tools to streamline this process. 3. Disconnection from Design Workflows: Most assessments function as static, post-design evaluations. There is a clear need for dynamic integration with BIM to enable real-time circularity feedback during the design and construction phases.

This study addresses these gaps by developing a BIM-based, automated assessment tool tailored to the Taiwanese context.

3. Theory and Methods

This study aims to establish a theoretical framework for calculating building circularity using scientifically rigorous and quantitative methods that align with international standards while being adaptable to Taiwan’s construction context. Building upon localized research on the Building Circularity Index (BCI) conducted by Wang and Huang (2022) [13] and Zhang et al. (2021; 2022) [12,22], the framework adopts the Material Circularity Indicator (MCI) as its conceptual foundation and enhances the assessment system developed by Madaster. The model defines three measurable life cycle stages—construction, use, and demolition—based on material flow analysis, and structures the evaluation into four hierarchical levels: materials, components, systems, and the entire building. At the building level, six major subsystems are further distinguished: site, structure, shell, services, space and interior finishes, and furniture. On this basis, a set of operational formulas and computational tools is developed to enable circularity calculations across scales. Particular emphasis is placed on integration with Building Information Modeling (BIM), which supports automated data processing and dynamic assessment. The framework thus provides both a theoretical foundation and a practical tool for evaluating building circularity in a way that is systematic, scalable, and compatible with evolving digital construction practices.

3.1. Calculation of Circularity in the Life Cycle Phases of Building Materials: Construction, Use, and Demolition

Figure 3 illustrates a circularity index evaluation system for buildings, adapted from the Material Circularity Index (MCI) proposed by the Ellen MacArthur Foundation. The MCI provides an analytical representation of material flows across the product life cycle [23], serving as a framework to evaluate material destinations and circularity performance. It defines three primary life cycle stages: manufacturing, use, and end-of-life. When applied to the construction industry, these correspond to the building life cycle stages of construction, use, and demolition, each associated with distinct circular strategies and objectives.

At the (1) construction phase, circularity is assessed by comparing the mass of virgin materials with the mass of recycled, reused, or renewable inputs. During the (2) use phase, the expected service life of a building or component is evaluated relative to the average performance and the lifespan of similar products. Finally, at the (3) demolition phase, emphasis is placed on demolition quality and the recovery potential of reusable and recyclable materials and components extracted during renovation or deconstruction [24].

I.

Construction Phase Circularity Index

The material circularity during the construction phase depends on whether the input building materials are recycled. The goal is to increase the fraction of recycled materials. The parameters include: the Fraction of recycled materials, the Fraction of rapidly renewable materials, and the fraction of reused components. Formula (1) [Based on MCI Input Factors F_R, F_RR, F_U] [23]

$${CI}_{construction}=F_R+F_{RR}+F_U$$

(1)

F_R: Fraction of recycled materials (% of product mass).

F_RR: Fraction of rapidly renewable materials (% of product mass).

F_U: Fraction of products and/or components that are reused (% of product mass).

II.

Circularity Index for the Use Phase

The material recycling rate in the use phase is intended to improve the efficiency of product use, with the goal of increasing product durability. The calculation of the cycle rate at this stage can be obtained by the ratio of the expected life of the product used to the average life of the building level to which it belongs, formula (2) [Derived from MCI Utility Factor F(X)] [23]. Crucially, this formula is adaptable to various building typologies. For instance, while industrial buildings may have shorter operational cycles, the L_av parameter can be adjusted to 60 years or more for residential towers, allowing the same framework to accurately assess circularity across different sectors.

$${CI}_{use}={\displaystyle \frac{L}{L_{av}}}$$

(2)

L: Potential life of the product (in years).

L_av: Industry average lifespan of building layers (in years).

III.

Demolition Phase Circularity Index

The demolition phase addresses the removal and processing of materials at the end of a building’s service life, with the objective of maximizing material circularity. Its primary aim is to promote the reuse of components and the recycling of materials, thereby reducing reliance on incineration and landfill disposal. To derive circularity indicators for this phase, it is essential to evaluate the potential reuse scenarios for each material and product. The assessment distinguishes between three pathways: (1) material recycling, (2) component or product reuse, and (3) final waste disposal through landfill or incineration. In addition, the efficiency of the recycling process is incorporated into the calculation, accounting for secondary waste generated during dismantling and processing. The corresponding indicator is expressed as Formula (3) [Based on MCI Output Factors C_R, E_C, C_U] [23,24], which integrates the proportions of recyclable and reusable materials with the efficiency of recycling processes.

$${CI}_{end of life}=C_R\times E_C+C_U$$

(3)

C_R: Fraction of material that can potentially be recycled at the end of its useful life (% of product mass).

E_C: Efficiency of the recycling process during the dismantling and scrapping phase (%).

C_U: Fraction of components and products that can be reused at the end of their useful life (% of product mass).

3.2. Calculation of the Circularity of Each Building Unit: Materials, Elements, Systems, Buildings

According to Anastasiades [14] in 2023, architecture is divided into at least four levels: “materials”, “elements”, “systems” and “buildings”. For each hierarchical unit at a specific life stage, the product of the cyclical degree of the entity composed of the unit and its mass can be “summed up” and “divided” by the total mass of the unit to obtain the average value as the cyclical degree of the unit at that level at that specific stage Formulas (4) and (5).

$${CI}_{building layer}={\displaystyle \frac{\sum ({CI}_{product}\times M_{product})}{M_{building layer} }}$$

(4)

$${CI}_{building}={\displaystyle \frac{\sum ({CI }_{building layer}\times M_{building layer})}{M_{building} }}$$

(5)

3.3. Whole Building Circularity Index

When a building is considered as a single product, the overall circularity can be evaluated using the MCI [21]. The MCI assesses whether material flows follow a linear pattern and, based on this, infers the overall circulation rate of the product. For buildings, this approach enables a holistic assessment of circularity by integrating both material recovery potential and functional performance. The calculation incorporates two key factors: the Linear Flow Index (LFI), which represents the Fraction of non-recyclable and non-reusable material flows, and the Utility Factor (F(X)), which reflects the effective service life and functional utility of the building. The general expression of the Building Circularity Index is given as:

$$CI =1-LFI\times F\left(X\right)$$

(6)

• CI: Circularity index (unit %).
• LFI: Linear flow index (unit %).
• F(X): Utility factor (unit %).

where LFI (Linear Flow Index) measures the proportion of linear flow, calculated as:

$$LFI={\displaystyle \frac{V+W}{2M+\frac{W_F-W_C}{2}}}$$

(7)

where V is the mass of virgin raw material, W is the mass of unrecoverable waste, and M is the total mass of the product.

F(X) (Utility Factor): Reflects the product’s utility relative to the industry average, derived as:

$$F(X)={\displaystyle \frac{0.9}{X}}$$

(8)

$$X={\displaystyle \frac{L}{L_{av}}}$$

(9)

where L is the actual lifespan and L_av is the industry average lifespan.

3.4. Computing Architecture—Four Levels and Six Systems

Based on the preceding literature review and theoretical foundations, this study proposes a computational framework for assessing building circularity. The framework integrates four hierarchical levels—materials, components, systems, and buildings—together with six major subsystems: site, structure, shell, services, interior space and decoration, and furniture [24]. Circularity at each level and subsystem is calculated using the methodological formulas described above, thereby enabling a systematic and multi-scalar evaluation of material flows. This hierarchical taxonomy constitutes a universal ontology applicable to diverse building types, ranging from industrial plants to high-rise residential towers. Since all building typologies are composed of these fundamental levels, the evaluation logic remains consistent regardless of the specific function. The overall framework is illustrated in Figure 4.

4. Implementation

4.1. Implementation Process

Given that the stages of the building life cycle and the hierarchical complexity of buildings are substantially greater than those of typical products and their product–material relationships, a comprehensive assessment of building circularity—including both the overall structure and its constituent subsystems—requires the use of Building Information Modeling (BIM) and associated management tools. To this end, computational programming is employed to establish an automated BIM-based calculation process. The proposed implementation workflow is illustrated in Figure 5.

This study employs the “Wafer Works Erlin Plant New Construction Project,” undertaken by Liming Construction Co., Ltd. (Taichung, Taiwan) [25], as the case study. As the project is currently in the construction phase, the assessment is conducted through simulation based on the construction plan, design drawings, and model information. The site is located at Lot No. 0358-3, Zhongke Section, Erlin Township, Changhua County, and comprises a newly built technology factory for Wafer Works Corporation (Taoyuan, Taiwan) [26]. The total site area is 50,842 m², and the current phase includes seven buildings, each consisting of four floors above ground and one basement level. The planned structures include the CUB building, FAB building, chemical warehouse, gas building, waste warehouse, and Guardhouses A and B. For analysis, this study focuses on the CUB building (reinforced concrete, RC structure) and the chemical warehouse (steel-reinforced concrete, SRC structure).

In this study, the parameters required for the evaluation formulas were incorporated into the component fields of the project model. Using existing information exchange standards, circularity assessment data sheets were exported from Revit. These outputs were subsequently subjected to manual verification and tabulation, ensuring the completeness of the assessment dataset for all material entities within the project (Figure 6).

Within Revit, Dynamo provides a visual programming interface that operates through a drag-and-drop system of nodes. These nodes are broadly categorized into eight types. For example, List nodes are employed to manipulate data lists by grouping, sorting, or extracting specific items, while Math nodes perform numerical operations such as addition, subtraction, multiplication, division, square roots, and absolute values. In this research, the data sheets generated from the refined model served as input, and a customized automated calculation script was developed in Dynamo. The workflow began with designing the overall data processing sequence according to the required formulas, clarifying the logic of data extraction, processing, and computation. Subsequently, appropriate node types were selected for each segment of the logic and connected to form a complete automated pipeline. The resulting script functions as a reusable “assessment tool” that not only performs the necessary calculations but also visualizes the reasoning process and analytical outcomes of the study.

4.2. Material Circularity Data Collection

Based on the construction contract drawings of the Wafer Works Erlin Plant New Construction Project, this study identified the materials used in the structural system by reviewing the “General Notes for Reinforced Concrete (RC) Structures” and the “General Notes for Steel (SC) Structures.” According to the drawings, the structural system components were categorized into two major groups: RC and SC. Other systems and elements, such as composite sandwich panels, doors, and windows, were excluded from the assessment. This exclusion is due to the current insufficiency of supply chain data transparency; specifically, the lack of Material Passports or supplier declarations regarding raw material sources. Consequently, this study limits its scope to the structural system (RC and SRC) where verifiable data from construction drawings and mix designs was available.

To obtain analytical data for the RC components, a “Ready-Mixed Concrete Mix Design Sheet” was requested from the site construction office. For instance, in the case of Type I Portland cement, no blast furnace slag was added, resulting in a circularity value of zero for the cement portion. For concrete with a design strength of 140 kg/cm², it was estimated that each cubic meter contained 96 kg of recycled slag aggregate. The recycled fraction was therefore calculated as F_R = 96 ÷ 2305 = 0.0416 (4.16%), where M (product mass) is 2305 kg per cubic meter, and V (the mass of virgin raw materials used in production) was assumed to be equal to M due to direct mixing. The service life of the product (L) and the industry average life (L_av) were both assumed to be 60 years, in accordance with the LCBA building industry life cycle database, as no specific manufacturer data were provided.

Similarly, this study sequentially estimated the values for concrete with design strengths of 280 kg/cm² (meeting the Green Building Material standard for hydraulic concrete) and 350 kg/cm².

In addition, according to the product manual of China Steel Corporation (Kaohsiung, Taiwan) [27], the main components of structural steel include carbon, manganese, phosphorus, sulfur, silicon, and niobium, with primary raw materials consisting of iron ore, coal, and stone. As the manual does not specify the proportion of scrap steel used, this study instead referred to the “Green Manufacturing Process” description on the official CSC website [28] for analysis. Based on this source, the production of 1000 kg of steel billets requires 1580 kg of iron ore, 717 kg of coal, 300 kg of stone, 111 kg of scrap steel, 16 kg of alloy steel, and 11 kg of refractory materials, for a total input of 2735 kg. From these data, the following values were derived: (1) M (product mass, kg) = 1000 kg; (2) V (mass of virgin raw materials required for production, kg) = 2735 kg; and (3) F_R (fraction of recycled materials, %) = 111 ÷ 1000 = 11%. This provides part of the dataset required for assessment. Furthermore, according to the World Steel Association (2023) [28], the global steel recycling rate in the construction industry is estimated to be at least 85%. Although official statistics for construction steel recycling in Taiwan are currently unavailable, this global figure serves as a scientifically grounded reference. Given the high residual economic value of structural steel, local demolition practices—regardless of the specific technique used—almost invariably separate and sell steel to scrap dealers rather than landfilling it. Therefore, the 85% rate represents a conservative lower bound adaptable to the local context. It is also noteworthy that the proposed BIM framework allows this parameter to be dynamically updated within the Dynamo script as specific Taiwanese data becomes available. Accordingly, the end-of-life recoverable fraction (C_R) was set at 85%. Accordingly, the end-of-life recoverable fraction (C_R) was set at 85%. Integrating these findings, the evaluation data for the SC items were compiled and incorporated into the relevant components of the structural system in the Revit project (

Table 2. RC and SC project evaluation data summary.

	RC				SC
	The Engineering Strength 140 kg/cm2 Concrete	The Engineering Strength 280 kg/cm2 Concrete	The Engineering Strength 280 kg/cm2 Concrete (the Green Building Material Standard)	The Engineering Strength 350 kg/cm2 Concrete	A572 GR50 Steel
M: Product mass (kg)	2305 kg/M3	2324 kg/M3	2324 kg/M3	2324 kg/M3	7.85/M3
V: The mass of the source material used to make the product (kg)	2305 kg/M3	2324 kg/M3	2324 kg/M3	2324 kg/M3	2735 kg/M3
FR: Proportion of recycled materials	4.16%	6.54%	10.46%	7.74%	11%
FRR: Proportion of rapidly renewable materials	0%	0%	0%	0%	0%
FU: Proportion of products and/or components that are reused	0%	0%	0%	0%	0%
L: Potential life of the product	60 years	60 years	60 years	60 years	60 years
Lav: Industry average lifespan of building layers	60 years	60 years	60 years	60 years	60 years
CR: Proportion of material that can potentially be recycled at the end of its useful life	0%	0%	0%	0%	85%
EC: Efficiency of the recycling process during the dismantling and scrapping phase	75%	75%	75%	75%	75%
CU: Proportion of components and products that can be reused at the end of their useful life	0%	0%	0%	0%	0%
EF: Efficiency of the material recycling process (%)	75%	75%	75%	75%	75%

).

4.3. BIM-Based Automated Calculation

To operationalize the material parameters established in the previous section, this study employed Dynamo, a built-in Revit plug-in, to develop an automated workflow for circularity calculation and assessment (Figure 7). This visual script automates the computing logic, enabling dynamic and repeated evaluations in response to design changes without the need to export the model for external processing. Furthermore, by visualizing the reasoning process within the Revit environment, the tool enhances interoperability and effectively reduces the time costs associated with manual calculation.

Based on the CI values calculated for individual components, results were further aggregated to derive the total CI value at the structural system level. The automated evaluation workflow established in this study consists of the following steps:

• Modeling;
• Addition of component fields and input of corresponding parameters;
• Parameter extraction from components via Dynamo nodes;
• Automated calculation using scripts.

Through this process, a BIM-based method for assessing building circularity is implemented. If circular construction becomes a primary strategy for achieving sustainability in the future, this assessment method offers an effective means of quantifying the circularity performance of building projects.

4.4. Calculation Results of the Circularity of Each Item at the “Structural System” Level of the Project

This study primarily analyzed the structural systems and material circularity of two buildings: the CUB office building and the chemical warehouse.

This study analyzed the structural systems under two distinct scenarios to evaluate the impact of material selection:

• Baseline Scenario: Using the actual materials specified in the construction contract (e.g., standard RC with low recycled content).
• Improved Scenario: A hypothetical simulation where structural columns and beams are replaced with certified Green Building Materials (hydraulic concrete).

Analysis of CUB Office Building: Under the Baseline Scenario, The CUB office building, constructed with reinforced concrete (RC), exhibited an overall circularity of 12.64%. At the component level, the structural columns and beams using 280 kg/m² concrete achieved a circularity of 12.93%, while the slabs and RC walls using 140 kg/m² concrete recorded a circularity of 11.87%. To enhance circularity performance (Improved Scenario), the structural columns and beams were hypothetically replaced with hydraulic concrete that meets the Green Building Material standard. This modification increased the overall circularity to 13.92%, with the circularity of columns and beams rising markedly to 14.67%, while the slabs and RC walls remained unchanged at 11.87%.

Analysis of the chemical warehouse: By contrast, the chemical warehouse, constructed with steel-reinforced concrete (SRC), demonstrated a significantly higher overall circularity of 21.25%. The circularity varied across components: structural columns using 280 kg/m² concrete achieved 12.93%; RC combined with structural steel beams reached 16.22%; and slabs of the same material achieved the highest circularity at 32.01%. This score, significantly higher than that of pure RC elements, is primarily attributed to the composite nature of the SRC floor system, which typically incorporates steel decking. Since the assessment tool calculates circularity based on a mass-weighted average, and this study assumes a high end-of-life recovery rate (C_R = 85%) for steel due to its residual economic value, the significant steel content effectively offsets the lower circularity of the concrete portion. Meanwhile, RC walls constructed with 140 kg/m² concrete showed a circularity of 11.87%. (

Table 3. Calculation results of the project’s “structural system” level for each item’s cycle.

	CUB Building		CUB Building (Recycled Green Building Materials)		Chemical Warehouse Building
	Element Circularity	Element Total Mass	Element Circularity	Element Total Mass	Element Circularity	Element Total Mass
Column	0.1293	12,225,813.26	0.1467	12,225,813.26	0.1293	864,547.98
Beam	0.1293	6,467,018.84	0.1467	6,467,018.84	0.1622	505,686.72
Floor	0.1187	5,542,725.57	0.1187	5,542,725.57	0.3202	1,309,553.15
Wall	0.1187	1,288,724.42	0.1187	1,288,724.42	0.1187	464,764.06
System Circularity	0.1264 = 12.64%		0.1392 = 13.92%		0.2125 = 21.25%

)

5. Conclusions

This study successfully developed and validated a Building Information Modeling (BIM)-based computational framework designed for the quantitative assessment of building circularity. This pivotal contribution addresses the critical lack of a unified and objective methodology for circularity evaluation in Taiwan. By synthesizing established international indicators and tailoring them to local construction practices, the framework facilitates a comprehensive quantitative assessment across three core life cycle stages—construction, use, and demolition—and four hierarchical levels, ranging from materials and components to the system and the whole building. The case study involving the Wafer Works Erlin Plant demonstrably affirmed the tool’s robust feasibility and efficacy in tracking circular performance and identifying crucial factors that constrain material reuse and recycling.

5.1. Key Findings and Academic Contributions

The empirical findings indicate that buildings predominantly adhering to linear material flows yield comparatively lower circularity scores, whereas the strategic adoption of certified Green Building Materials can elevate performance. Consequently, the developed framework provides a proof of concept for quantitative evaluation, offering actionable, data-driven insights to support sustainability outcomes throughout the building life cycle.

From both academic and practical perspectives, this research offers significant contributions:

• Standardization of Assessment: The BIM framework provides a robust scientific foundation for the future standardization of building circularity assessment in Taiwan. This is instrumental in driving the application of recycled and durable materials, and in encouraging the systemic adoption of Design for Disassembly (DfD) principles and digital workflows.
• Integration of Novel Materials: The research forwards the prospect of integrating low-carbon, recyclable, and reusable novel cementitious, low-thermal-conductivity materials (e.g., those developed from industrial by-products like ultra-fine and co-fired fly ash). These materials, applicable in non-structural elements, thermal insulation layers, or 3D-printed components, offer a promising pathway to substantially reducing the building’s operational energy consumption and embodied carbon footprint [29].
• Applicability to Broader Building Typologies: Although this study validated the framework using an industrial case study (Wafer Works Erlin Plant), the proposed model is fully applicable to other building types, including residential towers. The assessment logic relies on intrinsic material properties (mass and flow) rather than building function. Furthermore, the automated BIM tool is scalable; as long as the material parameters are defined, the script can process the repetitive structural elements typical of high-rise residential projects without modification. This universality addresses the industry-wide need for a standardized assessment tool.
• Research Limitations: While this study establishes a robust BIM-based framework, certain limitations should be noted to contextualize the findings. First, the case study validation was primarily focused on structural systems (RC and SRC); other subsystems, such as the building envelope and interior finishes, were excluded due to the unavailability of verifiable raw material source data. Second, the accuracy of the circularity index relies heavily on the quality of input data. In the absence of specific manufacturer data (e.g., material passports), this study relied on general industry assumptions for parameters such as product lifespans (e.g., 60 years), which may not fully reflect specific product performance. Additionally, although the calculation process is automated via Dynamo, the workflow currently still requires a stage of manual verification to ensure data completeness. Future research should aim to expand the localized database for non-structural elements and further streamline the automation process to minimize manual intervention. Furthermore, this study did not perform a direct quantitative benchmarking against external tools (e.g., Madaster, WBCI) or extensive sensitivity analysis. Such comparisons are currently constrained by two factors: (1) Inconsistent Baselines: Significant differences exist between international models and Taiwan’s local practices regarding data collection methods and building characteristics. (2) Lack of Standardization: Taiwan currently lacks a unified assessment standard to define boundary conditions. Without these, direct numerical comparison with international benchmarks could yield misleading discrepancies.

5.2. Summary and Future Outlook

In summation, through the synergistic coupling of technical evaluation and innovative material applications, this research provides a vital academic resource and practical instrument to support Taiwan’s critical transition toward circular construction. By effectively embedding the principles of a circular economy within the built environment, this study offers a tangible contribution to global efforts aimed at achieving the Sustainable Development Goals (SDGs). To achieve high-level comparisons and optimization analyses in the future, two key conditions must be met:

• Acquisition of Non-Structural Data: The industry must adopt Material Passports to provide the missing raw material data for doors, windows, and finishes, enabling whole-building assessment.
• Unification of Assessment Standards: Establishing a standardized local assessment system is essential to align baselines with international tools, allowing for valid differential analysis and sensitivity testing.