Keywords

1 Introduction

The construction industry is directly related to the needs and dynamics of society development, but its rapid growth is also accompanied by negative consequences. The construction sector is responsible for significant energy consumption during stages such as building material production, construction, and building operation, as well as depletion of natural resources and other concerns during end-of-life processes. One of the primary concerns during this phase is Construction and Demolition Waste (CDW). Statistically, within the European Union, CDW represents on average more than 37.5% of the total amount of waste produced [1]. For instance, according to [2], disposal and landfilling of the mineral fraction, which accounts for the largest share of total CDW, is still the predominant form of management in some countries, particularly in Central and Eastern Europe, such as Bulgaria (more than 70%), Slovakia (almost 50%) and others. For Norway, this number varies between 40% of mineral CDW disposed of and almost 20% used for backfilling.

The increasing amount of waste generated during construction and demolition has heightened public concerns about the industry’s environmental impact, which raises questions about the use of sustainable practices such as implementing Circular Economy (CE) and focusing on effective CDW management solutions. CE principles require a rethinking of linear approaches to waste management and a paradigm shift. A novel CE concept is based on a business model system that aims to replace the conventional “end-of-life” concept to slow and narrow material flows and close the loop [3]. Implementing these principles leads to preventing resource wastage, prolonging the lifecycle of buildings and their components, and increasing waste recycling, including the CDW. In fact, the need to increase reuse and recycling CDW rates is driven not only by environmental impact considerations but also by the potential economic benefits and conservation of limited resources [4]. As the current rates of reuse and recycling of CDW are lagging behind the growing waste production, the implementation of CE could significantly reduce the landfilling of CDW and eliminate the amount of CDW in general [5].

Designing new buildings and planning for end-of-life scenarios using a combination of CE principles and digital tools such as Building Information Modeling (BIM) modeling helps to reduce future CDW coming from existing buildings and use it more effectively [6]. BIM technology has concentrated the interest of researchers studying CDW management and tens of studies can be detected internationally, with their number constantly increasing. In this study, the most recent research covering the ways BIM modeling can promote CDW effective and sustainable management along with CE practices is recorded and presented. The benefits, but also the challenges accompanying BIM’s implementation are gathered, while the various BIM-based tools developed by various researchers are thoroughly examined.

2 BIMs Implementation on CDW Management

CDW production is expected to rapidly increase in the following years, especially in the European Union (EU) where the building stock is old, with a great portion of it dated at the beginning of the 20th century [7]. BIM as a storage medium of multiple and extensive building properties can enhance CDW management and promote CE principles.

2.1 Analysis of BIM Properties

Most countries have established policies and regulations towards a CE, while among them several targeting CDW reduction and recovery. Nevertheless, according to a study conducted in North America and considering the existing regulations in that area, their effectiveness varies among the various building types [8]. Different building characteristics are not properly considered by the existing regulations, preventing optimum results. Meanwhile, the existing CDW tools present limitations, such as they are completely design-detached, and lack interoperability capabilities, while their environment does not promote stakeholders’ collaboration [9]. Urban Mining (UM) is indisputably connected to CE practices, with Material Flow Analysis (MFA) being one of its critical processes [10]. Material Intensity Coefficients (MICs) definition is a rather challenging process since their values are related to the geographical area, the local conditions, and the researchers’ approach. The aforementioned parameters limit the promotion and effectiveness of CE practices; thus the research interest has focused on BIM technology.

BIM-based CDW management techniques can be implemented even from an early-design stage of a building. Up to 15% extra waste is considered to be produced during the construction stage and is related to construction errors [11]. Nevertheless, BIM modeling can prevent these errors efficiently by eliminating design flaws. This is mainly related to the visualization and the high level of details that a BIM model contains, to which all involved stakeholders have access and can contribute to the optimization of the design phase [12]. According to construction industry experts from the UK, BIM modeling has several advantages when used for CDW management, as it allows the continuous assessment of the CDW amount and the management techniques throughout a building’s lifespan, it provides precise data about building’s materials, and components and if it is combined with other advanced technologies the whole CDW management process can be further optimized [9]. Other benefits from BIM implementation are the detailed planning and management of the construction materials’ delivery and the construction site, the design for deconstruction, the promotion of prefabrication, and the ability to plan and control everything 3D [13, 14].

Despite the benefits BIM modeling offers to CDW management, its actual implementation in the industry is still limited. In fact, according to a study conducted in Australia, less than half of the interviewed construction stakeholders use it in their projects [15]. Several parameters exist that hinder BIM’s wider implementation on CDW management. To begin with, the lack of regulatory framework and guidelines covering this field is one of the most deterrent parameters for the involved engineers, followed by the BIM’s software inability to exchange data on actual time with other End-of-Lifetime (EoL), CDW and Life Cycle Analysis (LCA) tools, while another parameter is the absence of available and credible Material and Component Banks (MCBs), leading to lack of knowledge about the material properties [12]. A study conducted in the UK revealed that there are five main reasons for the limited BIM implementation, which are the lack of experts in this field, the industry’s unwillingness to follow the new practices, the level of responsiveness of business models to these advanced techniques, and the lack of standardization from an early-design stage [16]. What is also pointed out in the various studies existing in this field, is that even if there have been many efforts to include BIM-based CDW management from an early-design stage, there are very limited studies on the technology’s implementation in existing buildings [13]. The main reason for this phenomenon is the lack of documentation and drawings for the majority of the existing buildings, which is challenging for the creation of a credible BIM model, so activities like scanning and point cloud creation are necessary for building the model, nevertheless they require expertise, and they are time-consuming [17].

Figure 1 presents, in brief, all the benefits and challenges that BIM-based CDW management has, as they were gathered from the literature and presented analytically in the previous paragraphs.

Fig. 1.
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Benefits and challenges of BIM-based models’ implementation in CDW management according to the international literature.

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2.2 Developed BIM-Based Tools

Several researchers have developed theoretical and/or practical frameworks to enhance the efficiency of CDW management practices making use of BIM technology. Analytically, a theoretical framework was presented in [18], targeting at reducing the produced CDW throughout a building’s lifespan and increasing the reuse and recycling rates. A cost-benefit analysis is also included in it, helping the involved stakeholders determine the optimum CDW management solution. The specific framework can be applied from an early design stage and is suitable also for renovation and demolition processes. Another framework addressing mainly existing buildings was developed in [19], where the building under examination is firstly scanned to build the BIM model, while in a following stage and depending on the treatment applied to each material and component, the demolition and the transportation processes can also be planned. By implementing this framework, reuse and recycling are promoted. In study [20], the researchers developed a framework for building a 3D BIM model for existing buildings, where images must be taken from the internal and the external side of the investigated building, with some overlapping between them. Then the BIM’s development is based on the photogrammetric point cloud. After creating the BIM model, the researchers have all the materials and components’ properties, so a precise CDW estimation is feasible, and combined with a cost-benefit analysis, the optimum demolition and CDW management planning can be determined.

Material Passports (MPs), as a database storing all the materials of a building and their properties, is an important CE tool. A BIM-based MP’s implementation in existing buildings was studied in [21], to assess the materials’ recyclability and the environmental impacts they have after the building’s demolition. Laser scanning was used by the researchers to create the point cloud and then develop the BIM model of the building, with the materials’ quantity and composition defined through demolition acquisition and UM processes. Based on an Austrian database related to new buildings, they calculated for each material the recyclability and environmental impacts. An interesting approach was also elaborated in [22], where the researchers included sustainability assessment indicators in the MP they developed. In more detail, shared parameters related to the indicators were created in Revit and then Dynamo Visual Programming was used to model the indicators so they can be calculated. The indicators that they integrated in the MP are the deconstructability score, the recovery score, and the environmental score. The MP was validated through a case study. Based on BIM models of various buildings, a web-based MCB was developed in [23]. In this database, to where all the involved stakeholders have access, all the information of a building’s materials is available and calculations of CDW, reusable and recyclable materials are constantly available. The whole process involves the extraction of a Dynamo script from Revit and using PHP and MYSQL the data can be stored in the MCB.

Many researchers focus on developing BIM plug-ins to extend their models’ abilities. For instance, a plug-in calculating the CDW amount produced in every phase of a building’s lifespan, according to the architectural, structural and mechanical BIM models, was presented in [24]. The data exported from the plug-in calculation can then be used by an LCA tool to assess the environmental impact. The researchers validated their tool with a case study, and they concluded that using the BIM model to manage CDW from an early design stage can promote design for deconstruction and reduce the CDW production in all stages. A BIM add-in, called WE-BIM Add-in, provides the construction stakeholders the ability to calculate the CDW production (types and quantity) from an early design stage so that solutions for reducing them can be adopted [25]. A BIM plug-in presented in [26] aims at increasing deconstruction and reducing CDW production, by categorizing all the elements of a building to be renovated or demolished and uploading the data in an online shop to which is connected. Based on the customers’ demands the elements’ dismantling is prioritized, while for the rest elements that received no interest a conventional demolition procedure can be followed. Furthermore, a BIM-based tool targeting effective demolition waste management was developed, which can be implemented from the design stage [27]. The demolition waste amount is calculated from the data provided by the BIM model, its optimum treatment can be defined by making use of Geographic Information System (GIS) technology, and by using an LCA tool the environmental impacts can be also assessed.

Cost optimization in CDW management can be achieved easier through BIM implementation, as the involved stakeholders have a clear view of the whole process even from an early design stage. For instance, in [28], they developed a system where data from the building’s BIM model are extracted into the Microsoft Access database, and a detailed CDW calculation is feasible. Then a cost-optimization can be conducted regarding the most convenient companies to be involved in the demolition and transportation processes along with the detailed planning of these procedures. In study [29], the researchers concluded that a BIM-based CDW management adaptation is cost-beneficial, as in the case study they examined the management cost reduced by up to 57% compared to the conventional CDW management practices, with the percentage increasing even more when taking into account the profit from selling reusable and recyclable materials.

Continuing with BIM-based CDW tools, a BIM-based CDW information system was developed based on the 3R principle and a Reversed Logistics (RL) network defines the CDW management procedure, and the environmental costs are calculated through mathematical formulas [30]. Selected Greenhouse Gass Emissions (GHG) can be also evaluated both for recyclable and landfilled waste [31]. Finally, the addition of the time dimension in CDW management is also feasible with BIM modeling. According to a study calculating the potential on-site reuse and off-site recycling for concrete and drywall waste, tons of waste can be avoided due to the ability of 4D BIM to repeat the calculations for every component taking into account the actual construction sequence [32].

Table 1 displays all the aforementioned BIM-based CDW management tools, presenting their type, the tools used for their development, their main target and whether they were applied in a case study.

Table 1. Different types of BIM-based CDW management tools.
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3 Discussion/Conclusions

CDW production and its environmental impacts is a major issue that the construction industry is facing nowadays. CE closed-loop principles promise sustainable and efficient management; however, the current CDW management tools and the way national guidelines and regulations are formed, hinder full CE benefits. In this direction, EU promotes the integration of advanced technologies, like BIM modeling, in CDW practices to optimize their efficiency and achieve sustainability goals. In this review study, BIM-based CDW management properties and tools were presented and categorized briefly.

BIM technology provides the construction stakeholders with lots of benefits. BIM-based CDW management tools have been developed by several researchers and the results they present are satisfying and promising for further performance enhancement. CDW production seems to be reduced as clashes and construction errors can be detected even from an early design stage and eliminated. CDW calculation is also feasible throughout a building’s lifespan and detailed planning for all the CDW management stages can reduce costs and time.

Nevertheless, there are still some issues related to BIM technology that are challenging for proper CDW management. Interoperability between existing BIM software and CDW management or LCA or EoL tools is still not feasible, so more complicated and time-consuming solutions need to be implemented to overcome this problem. One of the most important issues on the credibility of the whole BIM-based CDW management relies on the accuracy and the detail of the BIM model. This inserts a level of uncertainty in existing buildings, as in most cases there is not enough documentation and drawings that can provide the necessary data for a proper BIM model development. To overcome this issue, many engineers and designers use statistical and local data, but the level of the model’s uncertainty in this case is relatively high. Other practices, like laser scanning and audits, are also adopted, but these techniques require expertise and are also time-consuming. This is the main reason why there is still a very limited number of studies for existing buildings.

To conclude, BIM-based CDW management is undoubtedly the future of CDW management, but there is still a need for further research since the field is in an immature stage.