1. Introduction
The importance of information and data management has been reevaluated due to the digital transformation of the architecture, engineering, and construction (AEC) industry. As a result of the design and construction process, a vast amount of data is created in various formats, structures, and levels of detail. Building information modeling (BIM) offers a model-based approach, in which the centralization of information is a basis for collaborative processes. Therefore, BIM is a powerful method for supporting the design, construction, and operation processes of buildings [
1,
2,
3]. As a result of standardization efforts, its application has become mandatory in various countries depending on the size or cost of the project [
4,
5]. However, despite the widespread adoption of the BIM methodology, in architectural practice, numerous documents must be submitted to authorities to obtain a building permit, where 2D documentation is still required.
The design documentation of a building generally consists of plans, technical specifications, and lists. Based on the regulation of the Hungarian Chamber of Architects [
6] the execution documentation of buildings consists of the main plans of the building (site plan, floor plans, sections, and facades), the architectural technical description, the bill of quantities, and all additional textual or design work that facilitates communication between the client and contractor, contributing to the quality construction of the building. Generally, the list of rooms, the consignment of fenestrations, details of joints, structural plans, and ceiling plans are also parts of the execution documentation, depending on the project type. The architectural technical description defines the goal of the project, the design program, the architectural concept, and the applied materials, structures, and fenestrations. It means that the layer structure of all slab, floor, roof, and wall structures, including the designation, quality, and dimensions of the materials constituting the composite structures, must either be included in the plans or referenced in the specification [
6].
Generally, these documentations are created manually, therefore the occurrence of design errors is unavoidable. According to Suther [
7], a design error is “a deviation from the plans and specifications”. Based on the study of Juszcyk et al. [
8], the most frequent errors in designs include the following:
The discrepancy between the technical description and drawings;
No detailed information about technology or materials;
Incorrect or incomplete descriptions of elements.
The multitude of error possibilities inherent in manual documentation is confirmed by a survey conducted by Kozik and Plebankiewicz [
9] in Poland on 268 bidding procedures. During the preparation of the bids, 19% of the questions raised were connected to the materials to be used, while 10% requested more precise information on the client’s requirements for materials and possibilities of applying substitutive materials. Besides the deficiencies in the technical description, also the changes during the project have a significant impact on the cost and schedule [
10]. There are many sources of construction changes, such as revised client requirements, the change in the scope of the project, incomplete/inconsistent drawings, design errors, changes in codes and regulations, unforeseen events and site conditions, delays in decision making, schedule pressure, etc. Furthermore, there is a high degree of uncertainty in the early design stages of a project, the imprecise and vague knowledge or the lack of design information is also one of the most common sources of construction changes [
11,
12]. Therefore, an effective change management system is essential to avoid contract disputes and project failure. Several researchers studied [
13,
14,
15] the applicable methods and technologies for change management and their impacts on the risk and cost management of construction projects. However, there are few practical examples in the literature for the effective management of changes in documentation. At the same time, the technical description includes several elements that also need modification with changes to the building model, which cannot be easily managed with the manual method commonly used in practice even today.
Changes often affect the applied materials and, therefore, also the composite structure specification. Here, the term composite structures refers to architectural or structural elements consisting of multiple layers of different materials and thicknesses, applied in the construction of individual building components, such as walls, floors, and roofs. The arrangement of these layers follows the construction sequence. In BIM authoring software (i.e., Archicad, Allplan, Revit, etc.), composite structures can be applied to 3D objects (walls, slabs, roofs, and shells); therefore, the thickness and material of the layers are provided by the model. Since the BIM model is the source of the quantity take-off, the appropriate definition of the composite structures is crucial. Generally, the architectural technical description provides detailed information on the composite structures, surpassing the extent of information provided by the BIM model. Each layer combination should be described in detail, including every relevant technical requirement, such as the structural, thermal, and acoustic performances, along with potential substitute products. This document can go up to 100 pages for a larger, more complex building. Usually, a separate, specialized designer is responsible for the design of the building materials used in the building. This designer is called a construction engineer. The construction engineer is typically a specialist architect who takes into account several aspects (i.e., building physics, energy consumption, feasibility, etc.) when designing layer combinations. The documentation of multi-layered structures is typically written in text format using a word program. However, this approach does not support the BIM environment that is gaining ground in the construction industry, since the manual inspection and modification of each layer are time-consuming, cost-intensive, and can increase the risk of human error [
16]. This issue is analogous to the challenges of implementing construction regulations in a BIM environment, as several studies [
17,
18] highlight the importance of converting textual information into a machine-readable format. C. Eastman et al. [
19], the developers of the fundamental principles of BIM, addressed the issue of automated rule-based building compliance checks using IFC models long before the method’s widespread implementation. This approach necessitates the conversion of regulations into a structured format, a topic that has been addressed by several researchers since then. Zhong et al. [
17] proposed a hybrid deep neural network for the automatic extraction of construction constraints. Peng and Liu [
20] applied natural language processing technology to transform the specifications of drawings into a machine-understandable knowledge graph pattern using BIM technology. However, data extraction from textual documents remains a challenging task, requiring heavy feature engineering expertise, which also pertains to the use of composite structures’ specifications in the BIM environment.
ISO 19650-1 introduces the Common Data Environment (CDE) as a technical solution to data management [
1,
21]. The CDE provides a central platform for the participants by collecting, managing, and sharing information. In practice, usually, cloud-based software solutions are applied, for instance, Trimble Connect, BIMcloud, Autodesk BIM 360, Allplan BIMplus, or Plannerly. These platforms are capable of managing different formats, like IFC (Industry Foundation Classes), the native formats of the authoring software, or simple text documents. Although this flexibility can be advantageous, it may be used as a document management system resulting in ill-structured or poorly coordinated data in some cases [
22]. Regarding the current documentation management practice, the focus is mainly shifted to the utilization of cloud-based platforms for file organization [
23,
24]. Nevertheless, these platforms, in the absence of a real-time connection to the model, primarily operate as conventional document management systems and do not embody the concept of a common data environment. Several researchers [
25,
26] are focusing on the challenges of integrating BIM and data from the Internet of Things (IoT), which could bring a paradigm shift to the construction industry by improving efficiency and transparency in an unprecedented manner. However, without standards or guidelines for information integration and data management, organizing large and heterogeneous data sets into a usable format is both costly and time-consuming. Consequently, poorly designed and implemented information integration and management systems can impede the future development of IoT and BIM-enabled smart environments [
27].
Information management is therefore very important in the AEC industry, and the spread of the BIM method also reinforces this. However, there are few articles dealing with the information content related to building materials [
28], despite the fact that it also affects the character and operation of the building. This topic is mainly found in areas dealing with sustainability, LCA, and various simulations, probably because these are the directions where the data on the characteristics of building materials affect the entire calculation and it takes a lot of time at the beginning for the designer to enter all the data into the software [
29]. However, structural designers also work further on these, for example in the form of composite loads, and design based on them. In this area, the weight load of materials is typically negligible compared to other loads, so the practice is to round up and combine load areas. This process usually needs to be iterated many times, and it is a relatively simple, repetitive task. It can be performed by an intern, whose salary is typically lower, so it is not necessarily worth developing for this. The data are also used during mechanical design and building physics design. It also affects fire protection, influences construction work, and so on [
30].
The practice of designing building materials also varies from country to country; in some places, separate composite documentation is prepared (e.g., Hungary) or a key note is prepared (e.g., England and Australia), in some places a building physics designer prepares the description of the characteristics affecting building physics, and the rest is designed by the architect (e.g., Switzerland). So not only is the documentation process different, but also who designs it [
31]. This is why it is difficult to develop a general solution.
This study presents and compares three different methods for creating the composite structures’ specification. Alongside the description of the traditional text format specification, a database-like and a web-based approach are introduced in this study. These developments facilitate the selection of building materials according to the technical requirements, as well as the formulation of the composite structures’ specification. The conditions and required time of application of these methods, and their possibilities for integration into the BIM environment, were examined through tests conducted by students within the framework of an academic course and a construction engineer with wide-ranging expertise in the field.
2. Research Method
The goal of this research is to add the design process of construction materials onto a BIM platform and to develop different methodologies to achieve this goal. Based on the literature review and practical experience gained in this field, a database-like and a web application method were developed for facilitating the design and documentation process of composite structures and providing structured data for the BIM method. The developed methods are tailored to the Hungarian field, however its underlying principles hold relevance for international utilization.
Handling and accessing construction material data are crucial for every discipline, as they fundamentally determine the building. Managing these data according to various aspects is important during both the design and construction phases. The approach to optimizing power networks through clustering and particle swarm optimization presented in Ourang Shiva’s and Ourang Armin’s paper could provide a methodological analogy for optimizing resource and data management in large-scale construction projects using BIM [
32]. In the long term, it would be worthwhile to examine targeted optimization following the efficient management of data based on our developed methods.
This paper presents a comparative analysis of the two newly developed methods along with the traditional Word-based method. The different methods have been applied one by one to several projects in order to evaluate them in terms of usability, convenience, interoperability between projects, accuracy, and linkability to the BIM model. First, the traditional method was analyzed, which led to the development of a database-like method as a proof of concept. This method was also tested in various projects. Based on the experiences from these tests, a dedicated web application was subsequently developed.
The comparison of the three methods was conducted through two independent experiments. The first one took place in a university environment, during the BIM management course at Széchenyi University, Faculty of Architecture, Civil Engineering, and Transport Sciences, in the first semester of 2023/2024. The aim of the course is that students work in small groups and design a given building on BIM bases. Two groups participated in the experiment, and from each group 3 students independently performed the 3 composite writing methods. All participating architecture students were in their final stage of study, in their 7th semester during the experiment. In the second experiment, the methods were implemented in a live design project for large public buildings design tasks between the years 2021 and 2023. Since, for real, expensive projects, it was not expected that one designer could produce the same design using three methods, the methods were applied to different but comparable projects and the designer was always the same. Thus, a peer review became available.
Figure 1 shows the flowchart of the research.
2.1. Traditional Method—Text Format
In the initial design phase, the construction engineer will provide instructions on the dimensional requirements of the building materials for the preparation of the sketches and draw up scale drawings of typical composite structures. These drawings are subsequently developed in detail, during which all the composite involved are precisely defined.
In the subsequent phases, the design progresses through several iterations, where the final material requirements are continuously refined. This process includes holding regular meetings, email exchanges, and producing sketches. The selection of materials is often based on information found on the Internet and consultation with manufacturers. The designer then looks through the various options, selects the materials that meets the requirements of the project, and writes out the technical requirements for it. Over the years and over the course of several projects, the construction engineer will collect a considerable amount of material and layer data. However, these materials are typically organized and scattered on the computer according to different projects. Copying materials and layers to current projects often depends on the designer’s memory, remembering which materials were used previously on which projects.
Traditional method refers to simple text-editing solutions used in computer-aided design. One of the most widespread solutions is Microsoft Word due to its high level of user-friendliness, direct compatibility possibilities, wide range of features, and easy accessibility. In this document, each composite structure has a code, which is also presented in the sections and connecting plans facilitating the identification of applied materials used in various locations of the building. The individual layers of the composite structures are arranged in accordance with the sequence of construction. The minimum information content of each layer includes thickness, the detailed material specification, and the potential substitute materials. The material specification must include the type of building material used and the requirements imposed on it. For instance, in the case of load-bearing elements, the strength of the structural material should be specified, while for insulating layers, thermal properties, such as the heat transfer coefficient, should be provided. For this reason, in practice, specific products are often referred to as examples, whose performance can be the basis when looking for equivalent substitutions.
Figure 2 shows such a documentation of composite structures.
The process of loading data into the BIM model is typically a manual solution. In practice, the construction designer creates the composite plans, and the architects incorporate them into the BIM software. In case of observations, they communicate via email, phone, or meetings. The construction designer processes the feedback, sends it to the architect, and this process repeats multiple times until the design is finalized. Due to the high degree of manual handling, data integrity is questionable, and the process contains many potential errors. This method is generally used for both small- and large-scale buildings, with the difference that there is usually no construction designer for smaller buildings; the architect handles that task.
This method does not require special software or extra computing power. The computing requirements of BIM software are sufficient to run the text editor tool as well. As the project size increases, the process of planning building materials also proportionally increases because there are no process-accelerating solutions; each composite structure must be handled individually.
From a data security perspective, since the documents are typically stored on the designer’s computer or server, it is essential to ensure firewall protection for these devices. Data exchange is usually carried out via email, followed by loading into the modeling software. Since it is a manual process, it is crucial to double-check and prioritize verification, possibly involving another colleague to better identify any discrepancies.
2.2. Database-Like Method
The first step was to validate the theory, so that arranged composite structure specification is the key to BIM applicability. It is necessary to associate data with the model elements. Excel was the most obvious solution for this, as it is widely used. This interface enables the systematic documentation of composite structures in a structured, editable format. With this method, the goal was to be able to provide the core functionality that the traditional method represents/contains in an organized format.
The utilization of Excel is particularly noteworthy due to its widespread accessibility, spreadsheet data management capabilities, programmability, and other inherent features. Excel’s functions, table capability, conditional formatting, cell storage, and programming capabilities made it possible to implement all the necessary functions in a structured environment and programmed buttons make it easier and faster to use. Furthermore, this method was chosen because, with the help of the VBA programming language, custom functions can be created and assigned to buttons, effectively adding extra functionality to the software. Additionally, by locking cells and worksheets, it can be regulated where designers can enter values, ensuring that they do not interfere with the automated processes. Using functions also allows for data management, such as automatically summing composite thicknesses.
The database [
30,
33] is divided into three primary groups, delineated across three worksheet categories: building materials (highlighted in orange), material layer specification interface (highlighted in blue), and assistant sheets (highlighted in green) (
Figure 3). Throughout the program, the fundamental principle was set so that cells with a blue background are free for editing, and “administrator” permission is required for the modification of others. Excel’s non-editable cells, programmed buttons, and password protection ensure errors are reduced and guarantee the file’s proper functionality.
The construction engineer has the autonomy to thematically organize construction products on material store worksheets (orange background). Materials added to these auxiliary sheets can be used on the main composite structure specification (blue background) worksheet, so that the appropriate materials can be selected for each composite structure from lists, without having to type in the name of the material, its properties, etc. In the top right-hand corner are the buttons, meticulously programmed in VBA, which are essential for the operation. Controlled by these buttons, several functions are made available, including the ability to create, copy, and delete a composite structure unit. In addition, users can create and delete new line items, manage lists, and navigate the interface—among these, the navigation feature stands out as a popular tool, similar to the menu used by Word enthusiasts to navigate through the highlighted search text.
The structured environment allows the linking of all building material and composite structure data to the BIM model, if the composite code is included in the model element. In this case, the data can be easily linked using the listing function of the BIM software (Archicad, Revit, etc.) [
30,
33].
During the permitting and construction processes, the formatted text document is preferred as it is more readable and the usual look helps in understanding the designed material concepts. The database format allows the data to be used in various reporting programs (Power BIM, Stimulsoft, etc.), which can easily format the data to the look and feel desired by the designer.
The process of loading data into the BIM model can be automated because the method’s core principle is structured data. These structured data sets can be connected to the BIM model. Modeling software typically can generate lists of building materials and export model element characteristics to Excel. By linking these with the composite Excel created by the designer (e.g., using a VLOOKUP function), the characteristics of the building materials can be assigned to the model-based Excel, then reloaded into the model, thus minimizing the possibility of errors.
Observation and design iterations occur similarly through various format discussions, and the modified composite data can be loaded into the model using the previously mentioned method. This approach generally works for both small- and large-scale buildings, but it is particularly advantageous for larger projects. This is because data importation can be automated, eliminating the need for manually entering building material data into the model. As the project size increases, the time required for managing building materials information decreases because the process can be automated, requiring only security checks to ensure that all information has been correctly transferred. This method does not require special software or extra computing power. The computing requirements of BIM software are sufficient to run the text editor tool as well.
From a data security perspective, it is similar to traditional methods. Since it is a desktop application, attention must be paid to the protection of the computer. The essence of the database-like solution is that composite data can be automatically loaded into the model. For this, the data must be in the same structure, which is ensured by the “programmed” Excel format, preventing the designer from entering data in any other way. The linking function must be precise during loading, and we recommend occasional spot checks to ensure the process runs accurately.
2.3. Web Application Method
After utilizing the manual word-processing method and the database-like format to provide structured data, the web-based, custom software approach seemed to be the next step. Neither solution was originally designed for writing composite structure documentation, so both methods encountered practical difficulties. The text format could not be automated and the data could not be further processed. The database-like method was not transparent, navigation was difficult, and the functions could break, requiring an administrator to fix them. If an error occurred, in the case of the text format, the designer knew which software was being used and could fix it. For example, if multiple construction designers worked on a documentation and one accidentally moved a text section and saved the file without noticing, it could be corrected using the cut-and-paste function, although it required manually finding where each part belonged.
In the case of the database-like method, if something was wrong, the colleague who created the Excel sheet was needed. Practically, this was because they knew the passwords and had a comprehensive understanding of the many functions and VBA code, so they had to be contacted to make corrections. However, if there was another colleague who was very proficient with Excel, the passwords could be shared with them to ensure that more than one person could understand and manage the developed composite writer Excel. An example issue might be that, due to many modifications, cell references were misaligned, and the layer thickness summing function did not add all the necessary numbers. In such cases, the creator needed to review the functions and modification buttons to correct the misalignment.
With the web-based solution, functions can be developed to meet specific needs, dedicated to the purpose of composite writing. The interface can also be designed to support the visualization and management of composite structures. The web application, due to Internet connection, allows users to always have the availability of project composite structures, to view or even edit it from any device and provides the possibility to design and operate the application as optimal. With a well-defined specification and thorough testing, it is unlikely that additional requirements will arise as the process is the same for each project.
When developing a web application, it is crucial to place a strong emphasis on data security from the very beginning, as it typically involves sensitive information. The following solutions have been implemented to ensure that project data are protected from unauthorized access:
SSL Encryption: Requests between the website and users’ browsers are encrypted using SSL. This ensures that the data cannot be intercepted or modified during transmission.
Password Hashing: User passwords are stored using secure, unique hashing methods, making it difficult to decipher the passwords, even in the event of a data breach.
Firewall: Multi-layered firewalls are used to protect against external attacks.
Backup: Regular data backups are performed and stored in a secure location, ensuring that data can be quickly restored in the event of a loss.
Role-based Access Control: Access to data is strictly regulated and only authorized personnel can access them.
The first step was to define the minimum viable product (MVP) [
35]. This is one of the first milestones in software development, the aim of which is to create a product that is ready to be presented to users and customers for their feedback and suggestions. In this case, the goal was to provide all the features that work in Word and Excel solutions but in a user-friendly way. The MVP includes the following core functionalities:
Project-based combination document writing;
Creation of layer combination (code, name, material name, and detail);
Material library;
Layer combination library.
Figure 4 shows the logic operation. Standalone layer combinations can be assigned to a project, which can be built from 0, or can be imported from the layer combination library, which becomes part of the project this way and can be edited. It is also possible to save combinations to the layer combination library, which can be used later in other projects, speeding up the workflow. The combinations are built from materials, which can be freely added to the desired combination unit or saved to the material library, from where they can be included and used in the project in the same way as the layer combination library content.
After the MVP and the logical operation were set up, the interface was designed and programmed. TSPC BIM Ltd. supported the implementation of the app by providing financial and development expertise. The interface of the developed app is shown in
Figure 5. As a project, it is possible to define who has access to the data by means of permissions, thus ensuring data security. After signing in, the user is immediately taken to the project layer combination editor interface, where the combinations can immediately be seen and edited. The Create a new Layer Combination button is used to add a new combination, and after entering the code and name, the addition of materials can begin. Combination units can be edited by selecting any of the combinations from the combination list on the left.
The project layer combination maker interface provides the following functions:
Create a new layer combination;
Add from a layer combination library;
Publish in Excel format;
Layer combination name;
Delete layer combination;
Add library material;
Add material;
Layer combination editor (thickness, name, and material specification).
The Combination Library (
Figure 6) contains all the composite structures that are frequently used or that are important to the designer and that are wanted to be used in other projects later. That is, the composite structures that have been saved in the library. In the combination library, composite structures are grouped by main categories (wall, floor, and roof). They can be edited, deleted, included in a project, or duplicated. Composite structures can be added to the library from a project or created directly in the library interface. All these data can also be searched using a dedicated search function.
The combination library interface provides the following functions:
The Material Library (
Figure 7) contains all the materials that are frequently used or that are important to the designer and that are wanted to use in other projects later. That is, the material that has been saved in the library. In the library, materials are grouped by main categories, like floor covering, insulation, separator layers, etc.). They can be edited, deleted, or duplicated. A material can be added to the library from a project or created directly in the library interface. All these data can also be searched using a dedicated search function.
The material library interface provides the following functions:
The process of loading into the BIM model is similar to the database-like solution since it can be achieved by exporting from the web app into an Excel format. The process and its characteristics are the same; the main difference is that the composite designer can create the composite documentation on a different platform with dedicated functions. The web-based application does not require extra computing power since the processing occurs through the web, not on the local computer. During the development of the web application, significant emphasis was placed on data security on the code side, with the main elements detailed earlier. Thus, regarding data integration, the same principles apply as with the database-like solution, meaning that careful function preparation and post-execution verification are necessary during the model and composite data integration.
5. Conclusions
This research aimed to integrate the design process of construction materials into a BIM platform by developing various methodologies. Based on the literature review and practical experience, a database-like method and a web application were created to facilitate the design and documentation of composite structures, providing structured data for BIM. The study compares these new methods with the traditional Word-based method, evaluating them on usability, convenience, interoperability, accuracy, and BIM linkability through two experiments. The first experiment involved architecture students at Széchenyi University, while the second applied the methods to live design projects for large public buildings from 2021 to 2023, ensuring consistency by having the same designer use each method on different but comparable projects.
In the student experiment, the traditional method required an average of 25–26 min per layer combination, while the database-like method required 14–20 min, and the web application method also required 25–26 min. The database-like method was found to be 44–46% faster than the traditional method. In terms of the expert assessment, the database-like method took approximately 1.2 min per composite structure, while the web application method took 6–9.6 min per combination. This shows that the database-like method was significantly faster by 84–87% compared to the web application method for the expert. Overall, the database-like method and the web application method demonstrated substantial improvements in efficiency and BIM compatibility over the traditional method, highlighting their potential for broader application in the construction industry.
Based on the student experiment, it can be stated that there was no significant time difference among the three methods, as the composite structures had to be completely constructed in each case, without any usable precedent or database. In contrast, the expert experiment showed that the Excel-based method was more time-efficient, attributable to the thorough knowledge of the software. Although the web application took more time to use than the Excel-based method in both the student and expert experiments, all participants agreed that with further development of the interface, creation of material libraries, and expansion of import options, an extremely user-friendly, BIM compatible tool could be established. Furthermore, by establishing a live connection between the application and BIM software, the building material management process could be significantly accelerated.
The importance of structured data is clear from the testing. The spread of BIM in the AEC field requires easy and immediate access to building data. For disciplines that build models, this need is easier to meet thanks to software solutions, but for those disciplines that “only” provide data (no model), this need is more difficult to meet. The easy accessibility and wide use of Excel and its versatility as a free tool make it a logical first step to link these disciplines into the BIM platform. Tests also show that it is possible to link material data to BIM models and also to generate the textual, official format in an automated way. However, Excel cannot provide a user-friendly, easy-to-use solution. A dedicated application designed to meet these needs is suitable. The development of the application allows the composite structure specification to be convenient and tailored to the needs of the construction designers, while at the same time being able to automatically interface with BIM. Custom product development is cost and time consuming, so an initial feature list, called MVP, was defined and was already suitable for testing. The completed application could then be tested and conclusions drawn. The essence of construction materials in a building is obvious, making it crucial for their data to be easily accessible. The developed solutions effectively support this need and facilitate smooth integration with the BIM environment. There remains significant potential for the further development of these methods, which could enhance efficiency during design and construction projects, ultimately contributing to more sustainable and efficient building practices.