This paper presents a real-time, cost-effective navigation and localization framework tailored for quadruped robot-based indoor inspections. A 4D Building Information Model is utilized to generate a navigation map, supporting robotic pose initialization and path planning. The framework integrates a cost-effective, multi-sensor SLAM system that combines inertial-corrected 2D laser scans with fused laser and visual-inertial SLAM. Additionally, a deep-learning-based object recognition model is trained for multi-dimensional reality capture, enhancing comprehensive indoor element inspection. Validated on a quadruped robot equipped with an RGB-D camera, IMU, and 2D LiDAR in an academic setting, the framework achieved collision-free navigation, reduced localization drift by 71.77 % compared to traditional SLAM methods, and provided accurate large-scale point cloud reconstruction with 0.119-m precision. Furthermore, the object detection model attained mean average precision scores of 73.7 % for 2D detection and 62.9 % for 3D detection.

Assessing cradle-to-site embodied carbon (EC) emissions enables stakeholders to make carbon-reduction decisions early. Discrete event simulation (DES) is useful for analyzing cradle-to-site EC by simulating construction operations. However, developing a DES model for cradle-to-site EC assessment in construction projects is time-consuming and error-prone. Therefore, this paper proposes an automated openBIM-based DES modeling approach. It starts with developing an integrated ontology of EC assessment, building information modeling (BIM) elements, and DES modeling to identify data requirements. It is followed by a BIM data verification flow using open standards, including extending Industry Foundation Classes (IFC) files and checking data integrity in IFC. Lastly, a general IFC-to-XML conversion tool is developed to convert processed IFC inputs into XML files, enabling the automation of DES modeling for cradle-to-site EC assessment. This openBIM-based DES solution was demonstrated in an actual project building. The results indicate that our approach can significantly improve DES modeling efficiency.

With the digital transformation of the construction industry, the need to improve construction business process collaboration and automation is increasing. However, as construction projects usually involve many stakeholders with complex relationships and insufficient mutual trust, the existing technologies cannot fulfill the requirements of the construction industry. This paper explores the integration of blockchain, smart contracts, and process automation technologies into construction business processes, shedding light on both managerial and technical challenges. The study introduces a comprehensive technical framework meticulously designed to align with the intricate nature of construction practices while focusing on the resolution of legal complexities associated with smart contract applications and the facilitation of process collaboration and automation. The framework comprises three core modules: (1) action definition and extension to process models, (2) standardized mapping for automatic smart contract generation, and (3) smart contract visualization for reliable process collaboration and automation. This multifaceted approach caters to the specific needs of construction management, standardization, interoperability, and visualization. The framework's practicality is further evaluated through real-world testing within a construction payment case, effectively showcasing its efficacy and applicability in tangible business scenarios. While this paper represents a significant step forward in addressing construction business process collaboration and automation challenges, it acknowledges the necessity for ongoing research and development to refine and expand these innovative solutions to meet the evolving demands of construction management. Currently, there is a significant escalation in the severity of disputes within the construction industry. The adoption of blockchain technology allows for the redistribution of trust within a construction project, shifting reliance from individuals to the system itself for better collaboration and fewer disputes. Although blockchain can help foster a more secure and transparent environment, at the process level, an efficient workflow engine is needed to activate processes in this environment. Therefore, this study proposed an approach to generating smart contract codes based on construction business processes in a standardized way and further visually executing these codes for the processes with historical transactions stored in blockchain. This approach can reduce the effort of smart contract programming and improve the standardization and credibility of smart contract generation. It can also streamline the procedure from construction business process design to final execution via predefined and visual modules. Meanwhile, the generation prototype is open sourced to provide transparency and further enhance the approach. To indicate practical implications in the real world, this study provided a case of construction payment, but the solution is not limited to the payment scenario.

The construction industry is commonly recognized as one of the most significant contributors to global carbon emissions. Apart from carbon emissions from energy consumption during the building operation stage, embodied carbon, including construction materials and construction activities in the building construction stage, becomes more and more important for life cycle carbon reduction in the construction industry. However, the process of embodied carbon quantification is tedious and error-prone due to the difficulty of collecting massive carbon data. Although Building Information Modelling (BIM) has been applied in this field to extract material information for carbon quantification, the existing studies are still limited in building the semantic domain information related to embodied carbon. Therefore, ontology tools are used and integrated with BIM in this study to create a comprehensive approach in the field of embodied carbon. An ontology-based data model is proposed first to identify information requirements for embodied carbon quantification. After that, this study developed a BIM-based tool to (1) enrich BIM information, (2) map data attributes in the ontology data model to BIM models, and (3) automatically calculate embodied carbon results. A typical building from a construction project is used to validate the proposed approach, which illustrates both feasibility and calculation performance.

Alleviating cybersecurity risks associated with centralized AI training and implementation is a burgeoning challenge in the construction industry. This paper addresses two primary questions: (1) What is the knowledge of AI security vulnerability in construction, and (2) How can AI be decentralized using blockchain? To this end, this paper proposes a blockchain-AI integrated framework (BAII), enabling AI to be trained, verified, and applied on a decentralized blockchain. The framework has been successfully validated in an excavator pose recognition scenario, demonstrating acceptable latency and high performance with 95 % accuracy, 94 % precision, and 96 % recall. This research is pivotal for construction managers and IT security professionals, enhancing the reliability and safety of AI applications in construction. The decentralized AI (DAI) approach can also inspire further research into motivating constructors to contribute to AI modeling and training through incentive mechanisms in the blockchain.

Blockchain technology is gaining increasing attention in BIM-based collaboration to enhance BIM security (e.g., traceability, integrity, and immutability). Due to the block size limitation, most existing BIM-blockchain interactions focus on recording BIM metadata (or attributes) on the blockchain. However, verifying the correctness or compliance of the input metadata is often overlooked, resulting in the sharing of incorrect versions, disputes over data ownership, and corrupted documents. Two research gaps have been identified: (1) a lack of domain knowledge for metadata compliance checking in BIM collaborative design and (2) an absence of methods to perform compliance checking when interacting with blockchain. Therefore, this paper proposes a blockchain-enabled common data environment (BECDE) framework that leverages a knowledge graph (KG) and smart contract technology. This framework makes three contributions to the body of knowledge: (1) It explores the mechanism of integrating KG with smart contracts and the CDE workflow to enable compliance checking in a distributed blockchain environment. Within this framework, two essential technical elements—compliance checking rules (CCRs) and “smarter” smart contracts (SSCs)—are identified. (2) It establishes the KG of the ISO 19650 standards to generate CCRs and develops Semantic Web Rule Language (SWRL) algorithms to convert the natural-language-based CCRs into blockchain-readable rules. (3) It develops SSC algorithms by incorporating CCRs to automate checking BIM metadata compliance before appending them to the blockchain. The BECDE framework is validated in three actual project BIM design scenarios, with results showing that (1) the SSCs outperform existing BIM smart contracts by improving the quality of input data within the blockchain and (2) the computing performances of the SSCs—with latency at the millisecond level and throughput around 250 transactions per second—meet the requirements of BIM-based collaboration. By integrating domain knowledge into a blockchain, the BECDE framework facilitates a trustworthy BIM environment where project members can rely on both data security and quality.

Conventional management mechanisms for construction waste recycling and reuse (CWRR) often cause considerable information asymmetry, inadequate government supervision, and imperfect incentive mechanisms, resulting in frequent illegal dumping and landfilling of construction waste and relatively low recycling rates. To address these issues, we introduce blockchain technology to CWRR. The design science research methodology was adopted to identify the main steps in functional requirement identification and blockchain framework development for CWRR. To explain how blockchain can improve the CWRR process, a conceptual model for the functional requirements of the proposed framework was constructed using qualitative analysis. A blockchain-driven framework was developed to overcome practical barriers in the CWRR industry. Based on scenario simulation results, the proposed framework had execution and transaction costs of $4.735 and $1.276, respectively, and latency performance at the millisecond level. The results indicate that (1) based on specific problems systematically identified from CWRR practices, the proposed framework can address practical barriers in the CWRR industry more directly; (2) the CWRR industry can use blockchain technology to achieve information sharing, comprehensive government supervision, and effective incentive mechanisms and (3) the blockchain-driven framework has high efficacy and can promote efficient CWRR and high-quality development of CWRR industry chain. This management model is conducive to forming a collaborative CWRR industry chain that can lead to broader adoption of blockchain technology across industries.

As one of the biggest resource consumers and carbon emitters, the construction industry plays a crucial role in global carbon reduction. Carbon certification or labelling schemes are efficient ways to assess and report the carbon footprints of construction materials and products (CMPs), providing the foundation for carbon management at the CMP level. However, existing carbon management for CMP certification relies heavily on traditional centralized data management tools, which suffer from data non-transparency and manipulation problems, making carbon footprints unreliable and hard to track. Therefore, benefiting from the immutability and traceability of blockchain, this paper introduces a distributed solution for transparent and secure carbon management towards CMP certification. Contributions lie in three aspects: (1) a Green Product Chain (GPChain) framework is proposed based on blockchain. This framework provides a distributed and transparent carbon data-sharing environment, enabling reliability and traceability during certification. (2) A blockchain data model is developed considering the privacy of carbon data for CMP certification. Besides, a privacy-preserving carbon data-sharing strategy is designed for pre-processing different sensitive data before being transferred to the blockchain. (3) GPChain smart contracts are developed to granularly control user interactions with blockchain and automatically generate distributed carbon footprint records. Results show that (1) GPChain's feasibility of supporting carbon management for GMP certification and (2) the acceptable performance of GPChain smart contracts during operations.

Environmental, social, and governance (ESG) considerations are increasingly becoming imperative and obligatory across various industries. The ESG performance within the architecture, engineering, and construction (AEC) industry is under heightened market scrutiny. However, current ESG management in construction is still in its infancy due to two limitations: (1) a deficiency in ESG knowledge, such as indicators pertinent to construction activities, and (2) a lack of data security in ESG management, culminating in inefficient and unreliable environmental management practices. Therefore, this paper employs the Design Science Research Method (DSRM) to introduce a Blockchain-ESG Integrated (BESGI) framework, facilitating traceable ESG data management within construction projects. This framework presents three significant contributions. First, it identifies ten AEC-ESG indicators by analyzing ESG methods. Second, it proposes a mapping approach for AEC-ESG indicators to construction projects for key ESG information access and data source identification. Third, it develops a blockchain-based data management mechanism for traceable ESG data management in the BESGI framework. It validates and evaluates the framework in a construction project in Hong Kong. The results show that the framework is usable and can save labor costs by 20.15% compared to traditional ESG management. This study offers a secure data management solution for ESG analysis of construction projects.

Integrating building information modeling (BIM) with emerging blockchain technology has gained considerable attention in addressing design collaboration problems like poor data security, weak traceability, and low transparency in off-site construction. However, blockchain implementations in off-site construction design, especially with openBIM standards, currently lack standardized workflow management and methods for ensuring data completeness within the blockchain environment. To bridge these gaps, this paper presents a novel blockchain-enabled platform-as-a-service (PaaS), specifically tailored for off-site construction to enhance interoperability and collaborative design efficiency using openBIM standards. The proposed PaaS offers two significant intellectual contributions: (1) a data contract system that manages openBIM workflow standardization and (2) a data escrow system that ensures the completeness and integrity of openBIM data. The data contract system utilizes an innovative asynchronous smart contract algorithm to streamline workflow checks, while the data escrow system introduces a new blockchain-driven data-checking strategy to ensure openBIM completeness at the data level. Besides, a PaaS architecture is developed to clarify the interaction logic between these two systems. The PaaS is validated and evaluated in openBIM-based design collaborations from a real-world project, with results indicating improvements: a 38% time-saving in design issue coordination and a 32% reduction in design data delivery time. Furthermore, the platform received favorable feedback from project participants, validating the approach and confirming the PaaS as a valuable tool for enhancing design collaboration in off-site construction.

Purpose This study aimed to improve the financing credit evaluation for small and medium-sized real estate enterprises (SMREEs). A financing credit evaluation model was proposed, and a blockchain-driven financing credit evaluation framework was designed to improve the transparency, credibility and applicability of the financing credit evaluation process. Design/methodology/approach The design science research methodology was adopted to identify the main steps in constructing the financing credit model and blockchain-driven framework. The fuzzy analytic hierarchy process (FAHP)–entropy weighting method (EWM)–set pair analysis (SPA) method was used to design a financing credit evaluation model. Moreover, the proposed framework was validated using data acquired from actual cases. Findings The results indicate that: (1) the proposed blockchain-driven financing credit evaluation framework can effectively realize a transparent evaluation process compared to the traditional financing credit evaluation system. (2) The proposed model has high effectiveness and can achieve efficient credit ranking, reflect SMREEs' credit status and help improve credit rating. Originality/value This study proposes a financing credit evaluation model of SMREEs based on the FAHP–EWM–SPA method. All credit rating data and evaluation process data are immediately stored in the proposed blockchain framework, and the immutable and traceable nature of blockchain enhances trust between nodes, improving the reliability of the financing credit evaluation process and results. In addition, this study partially fulfills the lack of investigations on blockchain adoption for SMREEs' financing credit.

Data accountability (i.e., data integrity and traceability) concerns existing construction cost management plat -forms due to the risk of data manipulation in a centralized paradigm. Blockchain is a promising technology that provides immutable and traceable data storage with a decentralized architecture. However, the transparency of blockchain conflicts with the confidentiality nature of cost information. Therefore, this paper presents a novel framework based on blockchain and encryption to preserve both data accountability and confidentiality in construction cost management. The proposed new framework involves the development of a cost data model containing the required confidential cost information to facilitate partially transparent recordings on the blockchain. An access control model based on symmetric and asymmetric encryption as well as proxy re-encryption mechanisms is developed to prevent unauthorized access to sensitive cost data on the blockchain and transfer data access in dynamic construction projects (i.e., construction projects involving new members continuously). Subsequently, encryption-integrated smart contracts are developed for automatic and secure cost activities on the blockchain. The framework is validated with a desirable latency (at the millisecond level), throughput (at the hundred level), and storage cost (at the MB level) in three illustrative cost management scenarios. The results indicate that project members can have accountable and confidential cost data for dispute resolution and cost analysis, respectively, as well as efficient cost data access transfer.

Implementing blockchain benefits various construction management processes, such as securing payments, enabling traceable design process, and enhancing information transparency in supply chain. However, blockchain implementation in construction is still in its infancy due to weak functionality of smart contracts, which are self-enforceable programs allowing iteration between external data and blockchain. In the context of construction management that embraces complex and dynamic business processes, smart contracts are currently designed based on specific and isolated functional requirements without considering the connection and execution logic between these functions. It leads to inefficient collaboration and even execution errors, thereby corrupting data quality and even causing business failure. Therefore, this paper proposes a Blockchain-BPMN (Business Process Model and Notation) integrated (BBI) framework for construction management. The framework poses two contributions. First, a BPMN-driven method is developed to design smart contracts supporting executing linked and logically connected business activities. Second, an access control strategy is integrated into smart contracts to safeguard the accessibility of sensitive business data in a blockchain environment. The BBI framework is validated in an actual BIM design collaboration scenario, and results show its feasibility and computational performance are acceptable. Several aspects for improvement and future directions are discussed in the end

A crucial action of COVID-19 combat is the quick design and building of makeshift hospitals (MHs). Although adopting building information modeling (BIM) promotes the digitalization and communication of design collaboration, data security vulnerabilities (e.g., lacking traceability and transparency) are detected and have inevitably impeded the efficiency and productivity of the MH project. Such problems often lead to rework and unnecessary disputes, wasting valuable time on projects requiring ultra-fast construction speed. The emerging blockchain technology offers an immutable and traceable collaboration environment. However, limited studies have integrated blockchain in the BIM design process, especially design in emergency projects like MH. Therefore, this paper proposes a blockchain-enabled collaboration (BEC) framework for fast and secure BIM design. The framework is illustrated in an actual MH project in Hong Kong, and results show that: (1) it supports secure and automated BIM data exchange and (2) it saves 23 % of the time in a design coordination case

Versioning in Building Information Modeling (BIM) is essential for design collaboration. However, current version control systems risk data manipulation because they rely on centralized versioning architecture, which might result in rewriting, losing design traceability, and causing arguments. Blockchain technology offers a decentralized, immutable, and traceable database model, making it a possible solution for secure version management. Therefore, this study presents a blockchain-based framework with two key contributions. First, a distributed versioning environment is established, leveraging blockchain and common data environment (CDE). Second, a smart contract cluster (SCC) is developed to automate versioning operations in the blockchain. The proposed framework is evaluated and validated in design scenarios based on an actual project. Results show that the blockchain is a promising solution for efficient and secure BIM versioning.

Managing versions of data for building information modeling (BIM) data is critical for design collaboration, especially with multiple disciplines involved where each team has specific data requirements and design procedures. However, existing version control approaches are still inefficient for two limitations: (1) lacking an efficient data structure for managing version dependencies among multi-disciplinary BIM models and (2) risking data manipulation due to a centralized versioning architecture that may lead to reworking, losing design traceability and raising disputes. Blockchain technology is an emerging and promising solution for version management as it provides a decentralized, immutable, and traceable database paradigm. Hence, this paper proposes a blockchain-aided solution for secure and efficient BIM versioning with three major innovations. Firstly, a two-layer container common data environment (TLCCDE) model integrating blockchain and Interplanetary File System (IPFS) is developed to illustrate an overall logic for BIM versioning in a distributed environment. Secondly, a smart contract swarm (SCS) is developed to automate versioning actions in the TLCCDE. Thirdly, a novel multi-branch structure (MBS) with efficient algorithms is designed to simultaneously manage version change continuity, issue attachment, and dependency compliance. The proposed TLCCDE model is evaluated and validated in design scenarios based on a real-world project. Results show that: (1) the TLCCDE model is workable in BIM versioning; (2) TLCCDE computing performance metrics, including SCS latency and throughput, as well as MBS latency and scalability, are all validated to be practical; and (3) the TLCCDE outperforms existing versioning approaches by augmenting dependency automation and versioning cybersecurity.

Blockchain technology has gained increasing attention in the construction sector. The process of developing a blockchain-based application that fits user requirements largely depends on the selection of a suitable consensus protocol, which acts as the centerpiece of blockchain architecture. In distributed networks, consensus protocols not only help maintain data consistency among all stakeholders, but also allow users to work together and stay secure. However, limited efforts have been delivered to analyze and compare existing consensus protocols under various construction scenarios, leading to uncertainties when applying blockchain technology in the construction domain. Therefore, this paper performs a critical review extracting literatures from (1) blockchain-based applications in the construction industry, and (2) existing blockchain consensus protocols. Additionally, a mixed method that integrates qualitative and quantitative analysis is proposed to evaluate the suitability of mainstream consensus protocols for various construction-related applications. Based on the selection criteria and efficiency requirements of consensus protocols generated, a recommendation strategy is also presented for consensus protocol selection under different construction scenarios. This study contributes to the following: (1) it helps construction stakeholders to understand the consensus process in a specific construction application case, and (2) it provides lucid reference guidance in developing a robust blockchain-based system underlying an appropriate consensus protocol.

Scheduling optimization of manufacturing prefabricated components is critical for construction in enhancing efficiency and productivity. However, problems of low formulation efficiency and low resource utilization still exist, impeding productivity and increasing costs. Although numerous efforts have been devoted to scheduling optimization, limited research has considered the parallel work of serial machines in production lines, leading to a deviation between actual situations and expectations. Therefore, a new optimization method is proposed with two major contributions. First, a Prefabricated Components Production Scheduling (PCPS) model considering the parallel work of serial machines is established, containing 3 new constraint conditions. a Position Algorithm (PA) is also designed to facilitate a constraint related to the locations of component groups. Second, a genetic algorithm-based method is designed to seek potential optimal scheduling schemes. The model is demonstrated and evaluated in an actual case. The results show that: (1) Optimal schedules calculated by the PCPS model can reduce penalty cost by 28.6% and total completion time by 14.9% compared to the case without considering the parallel work of serial machines. (2) Optimal schedules can effectively reduce penalty cost by 63.9% and total completion time by 34.4% compared to the empirical method of ascending order by the due date. The optimal schedules can provide a solution for more detailed and practical scheduling. For future improvement, other factors affecting productivity, such as operator proficiency, will be added to the model constraints.

AEC projects generate numerous versions of BIM models during the design and construction phases. This process is complicated by the sheer number of domains in large projects and the interlinkage of BIM deliverables (for example the structural BIM model follows the corresponding architectural BIM model). However, due to the generation of multiple versions and parallel design progress in different domains (especially in large projects), multi-domain delivery teams often fail to access and comply with the latest/required/approved design requirements during the progression of the design phase and complete issue addressing during the construction phase, which creates confusion, may lead to disputes. Moreover, due to the contractual nature of the parties involved data and process security is also very important. Therefore, this research presents blockchain-based secure coordination workflows for effective collaboration, parallel design progress, and issue management among BIM developers from multiple domains. Smart contract logic for facilitating dynamic dependency logic for coordinating linked multi-domain submission over the project timeline is presented. A method to ensure that issues are completely, and timely addressed, and related parties are held accountable for their actions or non-response is presented by integrating a BIM change identifier and blockchain in typical issue management workflows. The method considers collaborative design and issue management workflows for the secure, efficient, and complete design of BIM models. The method is validated using an ongoing large construction project in Hong Kong

Environmental, Social, and Governance (ESG) investing has become increasingly significant in the Architecture, Engineering, and Construction (AEC) industry. However, the AEC industry faces challenges such as non-uniform standards, complex information sources, and data security concerns when collecting and verifying ESG data. At the same time, as one of the key points of carbon emission in AEC projects, the ESG management of construction projects is still lacking. This paper proposed a blockchain-based ESG data management framework, which designed to address these challenges in the AEC industry. The framework and the smart contract and transaction data model applied in it realize data collection and information verification in construction projects. By leveraging blockchain technology's key features of transparency, immutability, and traceability, the framework ensures secure and efficient ESG data management. Additionally, the InterPlanetary File System (IPFS) technology enables access to original files for data verification and comparison, further enhancing authenticity. By integrating blockchain and IPFS technologies, our proposed solution enhances the reliability and traceability of ESG data in the construction projects, paving the way for more sustainable and transparent practices