1. Introduction
The Architecture, Engineering, and Construction (AEC) industry has undergone a remarkable evolution from dependence on two-dimensional (2D) Computer-Aided Design (CAD) building plans to the digitalisation and automation of design, construction, and operational processes through Building Information Modelling (BIM). Advances in BIM technology have stimulated a wide range of approaches to automating the code compliance checking process. Conventionally, designers and local authorities rely on 2D building plans to manually check the compliance of these plans with relevant building regulations. As the complexity of BIM models has increased, this procedure has become more time-consuming and could result in ambiguity and inconsistency in design assessments [
1]. The highly subjective nature of building regulations could further lead to inefficiency in the manual checking process [
2]. The automation of this process involves computer-programmed analysis of the building objects and attributes based on a set of regulations to produce a compliance report. An automated code compliance checking system promotes greater accuracy, consistency, and comprehensiveness in the design process compared to the manual checking procedure.
The essential components of an automated code compliance checking system are the rules and building objects [
3]. The building regulations should first be interpreted, followed by the identification of necessary building objects for the checking process. The relationship between these components should be determined to demonstrate the checking process. Given the complex nature of building regulations, a wide range of studies has explored approaches to interpreting the reasoning behind them. Early studies in the 1990s encouraged the development of expert systems in the CAD environment [
4,
5,
6,
7]. The emergence of BIM technology in the early 2000s propelled the development of automated systems to support the BIM-based environment. The CORENET e-PlanCheck system in Singapore [
8], Solibri Model Checker (SMC) in Finland [
9], DesignCheck in Australia [
10], SMARTcodes and spatial program validation in the United States [
3,
11], and Statsbygg’s design checking in Norway [
12] are among the prominent systems of the early 2000s. These automated systems were built through hard-coding techniques, also known as the ‘Black Box’ method. Despite its ability to eliminate errors during the rule execution process, this method hinders the involvement and accessibility of users to assess, modify, and extend the rules in the database [
3,
13,
14,
15].
Consequently, the application of a ‘White Box’ method has become prevalent in recent studies. This method provides greater transparency of the rule interpretation and execution process for users [
13,
15]. Examples of the White Box method are the semantic mark-up RASE (Requirement, Applicability, Selection, and Exception) methodology [
16], natural language processing (NLP) techniques [
17], visual programming language (VPL) techniques [
18], and an ontological approach through semantic web technologies [
19]. Despite the wide variety of approaches, challenges remain in the actual implementation of the automated system. Although the NLP and ontological approaches have a high level of success in translating complex rules, they have been argued to be impractical for AEC domain experts because of their complexity [
18,
20]. Parallel to the development of these approaches, logic-based approaches have been explored to extract the semantics of rules without requiring any programming skills [
15]. However, they include a preprocessing rule interpretation procedure and cannot directly transform the rules into computer representation. Alternatively, the VPL technique allows direct integration and greater accessibility for users to review and modify existing rules, as well as create new rules [
13,
21]. Despite the strength of VPL, the logic-based approaches remain relevant to avoid logical errors [
22].
For the identification of necessary building objects, existing studies favour the representation in BIM models of the Industry Foundation Classes (IFC) format, to promote better data interoperability. However, the modelling requirements for IFC data are known to be complex and require proficiency in the EXPRESS language [
23,
24]. This procedure tends to misclassify some IFC data, which could lead to data losses and errors [
23,
25,
26,
27].
The challenges to the automated code compliance checking field of study thus hinder the actual implementation in the real world. The challenges and limitations presented in past studies revealed the research gap in this field, in which the practicality for users were not prioritised during the development of an automated system [
28]. In conjunction with this, AEC experts should be involved in developing the rule database, rather than solely software developers [
15]. The separation of the rule interpretation process and the rule execution process could also provide greater accessibility, enabling users to maintain the rules during their use of the system. Using BIM models in native file format could also increase users’ accessibility. Thus, this study aims to develop an automated code compliance checking system through a user-friendly approach that includes a semi-automated rule translation process and the utilisation of BIM models in native file format, specifically the Revit file format.
The remainder of the study is organised as follows. In the next section, the background literature is reviewed to identify the strengths and limitations of the existing approaches and suggest a way forward. A framework containing the methods in developing the system is presented in
Section 3.
Section 4 demonstrates the implementation and validation of the framework in a case study, and
Section 5 presents the discussion of the results. The conclusion is set out in the final section.
3. Methods
Based on the knowledge gaps, this paper attempts to answer two key research questions: (1) What is a viable approach to accommodate the involvement of relevant experts in interpreting building regulations? (2) What is a practical approach for users in integrating and maintaining the rules in a BIM-based environment? In consideration with the research questions, the aim of this study is to develop an automated BIM-based code compliance checking system through a user-friendly approach. To accomplish this aim, this study aims to achieve the following objectives:
To structure the representation of rules and BIM properties for an automated code compliance checking system through a user-friendly approach.
To develop and validate a prototype of a BIM-based Automated System for Malaysian Code Compliance Checking (BIMSMACC).
A critical realist stance was adopted to critique the existing phenomena and convert them into change or improvement. This stance is aligned with design science research (DSR), which aims to improve the existing knowledge by creating artefacts [
80]. The DSR methodology was applied in this study to address the research questions through a problem-based approach [
81]. Abductive reasoning was applied to draw the current problems and proposed approaches from the literature and establish suggestions for improvement. Inductive reasoning was then applied to construct the artefacts through a qualitative approach. The artefacts, in the form of a framework and prototype, were demonstrated and validated. Iteration occurred between the stages to refine the artefacts.
Figure 1 illustrates the framework in developing the automated BIM-based code compliance checking system for fire safety regulations. The framework has four components: rule interpretation, building model preparation, rule execution, and rule reporting. These components are similar to the development stages proposed in a previous study [
3]. In the rule interpretation stage, the applicable fire safety regulations in Malaysia are formalised through a logic-based approach. This is followed by the building model preparation stage to identify the necessary BIM properties. The rule execution and reporting stage then simulates the code compliance checking process, where experts are involved in validating the system.
A total of 256 clauses from Part VII (Fire Requirements) and Part VIII (Fire Alarms, Fire Detection, Fire Extinguishment, and Fire Fighting Access) in the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012 were selected for the rule interpretation. The authors formalised the building regulations through a classification technique and semantic mark-up RASE methodology. The classification technique was employed to maintain the integrity and structure of the building regulations. Generally, previous studies introduced different classification techniques: (1) the categorisation of clauses into declarative, informative, or remaining clauses [
82]; (2) the classification of clauses into Class 1, Class 2, Class 3, or Class 4 [
83]; (3) the classification of clauses into Content, Provisory, Dependent, or Ambiguous concepts [
84]. The first classification technique [
85] was adopted as it includes provision for the clauses that are unsuitable for the automated code compliance checking process.
The semantic mark-up RASE methodology was then applied for declarative and informative clauses. This process decomposed the semantics of building regulations according to four operators: Requirement (<r>), Applicability (<a>), Selection (<s>), and Exception (<e>). The definition of each operator will be discussed in
Section 4. This approach was adopted in this paper and compared with other logic-based approaches such as decision tables and knowledge-based approach. Based on these three approaches, the semantic mark-up RASE methodology was the most promising method in the rule translation process as a substantial number of studies [
42,
43,
44,
74,
75] had tested it in their respective regulations.
Interview sessions with three fire safety experts were also conducted to assist in interpreting the informative clauses. These interview sessions encouraged the involvement of AEC professionals in interpreting the clauses, as suggested in previous studies [
3,
15]. In selecting the experts, purposeful sampling was conducted in which the samples were selected based on the knowledge and experience of relevant experts on fire safety design. The first expert was a Branch Chief of the Fire Safety Certification Branch, Fire and Rescue Department of Malaysia (JBPM) with an experience span of 33 years. The other two experts were fire engineers which are abreast with the emerging technologies and performance-based design related to fire safety in buildings.
Next, in the building model preparation stage, the authors identified the necessary BIM properties in native file format, specifically in Revit. A 17-storey institutional building BIM model was created in Revit for this purpose. Revit is popular among designers as it has a shallow learning curve and a user-friendly interface [
1,
86,
87]. In Malaysia, Revit has been the preferred BIM authoring software application since 2013, and the official platform for the Public Works Department (PWD) to create a library of families [
88,
89]. An organisation under the Construction Industry Development Board (CIDB), the myBIM centre, also uses Revit for their BIM training [
90]; the centre currently offers BIM training to AEC professionals to encourage BIM adoption in Malaysia. The identification of necessary BIM properties in the framework is based on the families and parameters in Revit. The necessary families are derived from <a> and <e> marked-up phrases while the parameters are derived from <r> and <e> marked-up phrases. The BIM properties act as input for the rule execution stage.
The rule execution stage then simulated the code compliance checking process. The authors developed pseudocodes as an initial step in establishing the relationship between the formalised rules and BIM properties. Past studies recommended the application of pseudocodes to support the encoding process and functionality of the automated system [
3,
15,
91]. A portion of the pseudocodes were then encoded through Dynamo, a visual programming tool in Revit, to develop a proof-of-concept prototype. The checking process and compliance results could then be run directly in Revit.
As the validation process is a major contribution of DSR [
82], thirteen experts were involved in validating the artefacts, to determine their completeness, accuracy, usability, and reliability. The validation process was conducted through interview sessions guided by structured questionnaires to gain feedback and constructive comments from the experts. Five experts—one representative from the fire authority, three fire engineers, and one architect—validated the framework. For the prototype, eight experts (three architects, two structural engineers, one mechanical engineer, and two civil engineers) were involved in the validation process. The experts were chosen for their qualifications, experience, and knowledge of the subject matter. In validating the elements in the system, several samples of formalised rules and BIM properties were presented to the experts. For the validation of prototype, its features and functions were first demonstrated to the experts. Next, the experts were invited to test the prototype through the Dynamo Player in Revit. Subsequently, in both validation processes, the experts provided feedback and filled out the questionnaires. Mean scores were calculated to analyse their answers.
4. Case Study (Implementation and Validation)
This section demonstrates the implementation of the proposed framework in developing a BIM-based Automated System for Malaysian Code Compliance Checking (BIMSMACC). The study formalised a total of 256 fire safety clauses; identified the necessary BIM properties; developed the pseudocodes; and lastly, created a proof-of-concept prototype.
4.1. Interpretation of Fire Safety Clauses
There are three stages in formalising the fire safety clauses: the categorisation process, the decomposition process, and the interpretation process through interview sessions.
4.1.1. Categorisation of Fire Safety Clauses
In formalizing the categorisation process,
Figure 2 was developed, where the authors initially identified the clauses that contain references to other clauses or regulations. This step was necessary due to the high occurrence of the interrelationship between clauses and dependence on the Schedules stipulated in the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012 as well as other regulations from the Malaysian Standards, British Standards, Australian Standards, and International Electronical Commission Standards. Following this procedure, all clauses, whether marked or not, were analysed in the first filter categorisation.
As presented in
Figure 1, the first filter categorisation identified clauses that contain straightforward rules such as geometrical or definite rules. These were extracted and categorised as declarative clauses. Other clauses were then channelled to the second filter categorisation to identify the informative clauses. Clauses that contain ambiguous terminology or arrangements—for instance, “where appropriate”, “suitable”, “adequate”, “as far as the practical”, or “furthermost point of the floor”—were grouped as informative clauses. In other instances, clauses that stated the requirement for special approval from the fire authority, which could lead to ambiguity, were also categorised as informative. Based on
Figure 1, Informative clauses also represented any clauses that provide options for designers, such as “either”, “where practical”, and “where impractical”. Clauses that were not suitable for the first and second filters were categorised as the remaining clauses. Through this categorisation process, a total of 166 declarative clauses, 53 informative clauses, and 37 remaining clauses were identified in the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012.
4.1.2. Decomposition of Semantics in Fire Safety Clauses
The declarative clauses were initially decomposed through the semantic markup RASE methodology, followed by the informative clauses. The <r> operator signified the rules in a clause and was associated with modal verbs. The modal verb “shall” was the most prevalent in the fire safety clauses to express necessity or prohibition in designing the building. For instance, by-law 167 paragraph 1 (
Figure 3) contains the modal verb “shall” to explain the requirements for storey exits. “Will” was also prevalent in other clauses, while “may” was frequently used in informative clauses to imply the design alternatives. The rules could also indicate prohibitions by having the word “no”.
The <a> and <s> operators represent the objects in the clauses. The <a> operator was applied to mark the main object in a clause while other objects were marked with <s> operators. In identifying the main object in a clause, imperative sentences that convey instructions or prohibitions were analysed. Subjects of the imperative sentences were considered as the objects in a clause. Due to their complex composition, many clauses contain more than one subject. Hence, the most distinct technique in identifying the main objects was to analyse the title of the by-laws. Since most by-laws contain more than one paragraph, the title represents the theme of the clauses under the same by-law, such as by-law 167 paragraph 1 (
Figure 3). In other circumstances, the main object in a clause was identified by referring to other clauses of the same by-law. Objects other than the main object were then marked with the <s> operator.
Phrases were then marked with the <e> operator to signify the exception to the rules in the clause, such as in
Figure 3, and to identify the exceptions of <a> and <s> marked-up phrases. By-law 158 paragraph 1 in
Figure 4 provides an application of the <e> operator to mark the exceptions of <s> marked-up phrases. Keywords such as “except”, “unless”, and “other than” were used to determine the <e> marked-up phrases.
The clauses with marked-up phrases were then illustrated in a tabular manner, as shown in
Table 1 Each marked-up phrase was ascribed to a topic, comparator, and target value. For <e> marked-up phrases, the topics were determined based on their nature. If the <e> marked-up phrases were exceptions to <r> marked-up phrases, then the topics would be the rules imposed in <r> marked-up phrases. On the other hand, if the <e> marked-up phrases were exceptions to either <a> or <s> marked-up phrases, then the topics were determined based on the topics of <a> or <s> marked-up phrases.
Next, the comparators and target values were identified for each phrase, as shown in
Table 2. The “equal”, “not equal”, “more than”, and “less than” comparators were applied for <r> marked-up phrases while the “include” and “exclude” comparators were applied for <a>, <s>, and <e> marked-up phrases. Any marked-up phrases containing references to other clauses or regulations were identified in the table, as shown in
Table 1, which was similar to the procedure in the categorisation process. Any topics, comparators, and target values in informative clauses that were ambiguous or provided options for designers were also labelled to acquire further interpretation from relevant fire safety experts.
The topics, comparators, and target values were organised to restructure the fire safety clauses so as to validate the accuracy of the decomposition process. The restructured clauses were written in prose form, as displayed in
Figure 5.
4.1.3. Interpretation of Clauses by Fire Safety Experts
A total of 53 informative clauses were further interpreted through interview sessions with a Branch Chief of the Fire Safety Certification Branch, the Fire and Rescue Department of Malaysia and two fire engineers. These interview sessions encouraged the involvement of AEC professionals in interpreting the clauses, as suggested in previous studies [
3,
15]. Four topics were directed to the fire safety experts: (1) exits and travel paths, (2) building elements, (3) ventilation systems, and (4) active fire protection systems. The fire engineers were responsible for interpreting clauses related to the design considerations, while the fire authority interpreted any clauses stating a requirement for special approval.
The fire engineers stated that determining travel distances without technological tools could be very subjective and prone to error. Thus, they believed that the interpretation of the furthermost point of the floor should not be derived from human judgement but instead from a computer application. Nevertheless, one of the respondents indicated that fire risk analysis is still relevant to determine the optimum travel paths. As stated by the fire engineers, the travel paths and building layout could influence the determination of the most practical distance between storey exits while also referring to other international regulations. Based on the fire safety clauses, the storey exits should be readily accessible at all times. The fire engineers interpreted that the doors should be situated within travel distance limits and unlocked during a fire incident. Thus, the locking mechanism of storey exits could be incorporated into the checking process. The fire safety clauses also mentioned the flexibility of designing horizontal exits in buildings. The fire engineers believed that the lack of clarity in this clause could potentially lead to evacuation problems. In this case, they suggested the use of a performance-based design to determine the availability of horizontal exits.
The informative clauses also provide options for designers in arranging the firestops and flame barriers for structural elements. As interpreted by the fire engineers, the placement of firestops and flame barriers are subject to fire risk analysis but should achieve the minimum fire resistance period requirement of the structural elements. For other design considerations that require special approval from the fire authority, such as protection for lift shaft openings, roof construction, and gangway layout, the Branch Chief officer stated that the fire authority would allow flexibility for designers to produce the appropriate fire safety solutions. Thus, this shows that although the fire authority has superior power in approving building designs, the responsibility and technical competence of designers to conduct a comprehensive compliance check are much higher than that of the fire authority.
For the arrangement of ventilation systems, ambiguities arose in the informative clauses over their design in protected lobbies and atria as well as the use of natural draught smoke vents. For the functional requirements of the pressurisation system in protected lobbies, the fire authority suggested applying Malaysian Standard 1472 (MS 1472). With the emergence of many pressurisation system products, the Branch Chief officer added that the fire authority could adapt to any new system that meets the requirements. Pressurisation systems were also strongly encouraged by the fire engineers in the staircase enclosures below ground floor level. For natural draught smoke vents, the fire engineers explained that these should be designed according to the smoke layer height, the size of the smoke reservoir, and the building’s function and geometry. Designers could refer to MS1780 for this purpose. The Branch Chief officer stressed that any closed-design smoke vents should open automatically with the activation of the fire alarm system and be subjected to the fire authority’s approval. Ambiguities also occurred in the requirements for designing ventilation ducts. In this case, the fire engineers interpreted that the arrangement of these ducts and their components largely depends on their analysis of the building.
As stipulated in the fire safety clauses, any active fire protection systems must be approved by the fire authority. Thus, as interpreted by the Branch Chief officer, the requirements in informative clauses should be followed based on the suitability of the building. For instance, the provision for additional fire hydrants depends on the building’s geometry, type, dimensions, and gradient of accessway. The protection method for the storage of fire hazardous material should also be based on the type of fire hazard in the building spaces. The Branch Chief officer explained that the components of fire protection systems, such as the material of cables and the capacity of the systems, should be suggested by the designers. All respondents believed that every building is unique and the design solution for one building may not apply to another building. They further stated that there is no rule of thumb regarding compliance with informative clauses in the fire safety regulations. The findings from these interview sessions were used as a basis for the target values in the rule execution process. In this case, designers and the fire authority could override the compliance results for informative clauses.
4.2. Identification of BIM Properties
The fire safety clauses were first arranged according to the building elements and spaces in defining the necessary BIM properties. Next, the marked-up phrases for each clause were extracted and integrated with BIM properties. As previously discussed, the <a> and <s> marked-up phrases represented the objects. Thus, these phrases were integrated with the families in Revit.
Table 2 provides examples. A total of 54 families in Revit were identified as necessary for the fire regulation compliance checking process. In ensuring standardisation in naming the families, the OmniClass™ classification system was used, and the numbers and descriptions of OmniClass™ (
Table 2) were added as parameters to the families. For example, the fire hose reels were represented by OmniClass Numbers 23–29 25 15 17.
The <r> and <e> marked-up phrases were then utilised to identify the necessary parameters in Revit, both built-in and new. Most dimension parameters such as width, length, and area; constraint parameters such as level, base constraint, and top offset; and material parameters were already embedded in Revit and used for the identification process.
Table 3 presents examples of the identification process for the wall family, and
Figure 6 shows the properties of the wall family in Revit. A similar identification process was applied to all families in Revit.
During the rule interpretation stage, the rules were analysed according to building type and space. For example, the compliance rules for dwellings differ from those for factories. The requirements for an occupied space and a circulation space also contain different sets of compliance rules. Therefore, the building types and building spaces were assigned specific names. Two classification systems were developed through Autodesk Classification Manager for the Revit
® add-in. This tool provides a classification system database file for users to create parameters with a set of predetermined values in Revit.
Figure 7 illustrates the uploaded database that could be applied to assign specific values to the parameters.
4.3. Encoding Process/Proof-of-Concept Prototype
Before encoding the rules into Revit, pseudocodes were developed to represent the algorithm for BIMSMACC. Two types of pseudocode modules were created: Search Modules and Checking Modules. Eleven Search Modules were created to process arrays in the schedules provided in the fire safety regulations, while nineteen Checking Modules were created to demonstrate the rule execution and reporting procedure. The Search Modules could be used to search for and select the appropriate requirements according to the building purpose groups, building spaces, and building elements. The Checking Modules were divided according to the building elements. In developing the modules, the topics, comparators, and target values from the marked-up phrases were utilised to influence the compliance results as either ‘PASS’ or ‘FAIL’.
All modules contain sub-modules to divide the task systematically. A Checking Module known as PC.00 was regarded as the mainline module for the compliance checking procedure, with subordinate modules such as PC.01, PC.02, and PC.03. These subordinate modules also contain further subordinate modules, such as PC.06.01 and PC.06.02 as subordinate modules of PC.06. The Search Modules are utilised in the Checking Modules to select appropriate requirements from the schedules in fire safety regulations. The BIM properties acted as the global data for all modules, and variables were drawn from these data to influence the compliance checking results. Desk checking was then conducted for all pseudocode modules to ensure the accuracy of the algorithms’ logic. Two programmers validated the pseudocodes through desk checking, and these experts confirmed that the pseudocodes were logically designed.
In encoding the rules in Revit, a prototype was developed through Dynamo to demonstrate a portion of the rule execution and reporting process for BIMSMACC. The pseudocodes acted as guidelines in developing the Dynamo scripts. The scope of this prototype was limited to fire doors and staircases in the BIM model. The compliance checking process in the prototype was driven by the manipulation of families and parameters in the BIM model. Seven families were manipulated for the prototype: project information, floor plan, room, wall, stairs, runs, and door families. Besides utilising the previously identified parameters, new parameters were purposely created to display the compliance results.
A total of eight Dynamo scripts were created where users can run the scripts through the Dynamo Player in Revit, as shown in
Figure 8. The reset scripts were created for validation purposes, where the values of relevant parameters could be reset to iterate the prototype testing. A user could run the ‘01 Check Individual Fire Door’ script to demonstrate the automated compliance checking process for fire doors. The script would check the fire resistance period (FRP) and standard specifications of a door family. The script would first prompt the user to select the door and then assess the type of door through its OmniClass Number. If the user selects a fire door, the script will extract the door’s fire resistance period and compare it with the required fire resistance period of the building, wall host, or building spaces. For compliance checking of the fire door’s specifications, the script will compare the value of the Standard Specifications parameter of the door family with the required standard. The compliance results will then be reflected in the Dynamo Player, the properties pane of the door, and the 3D view.
Figure 9 and
Figure 10 provide examples of a non-compliant fire door.
Three scripts were developed for the compliance checking process of staircases to avoid a large number of nodes in a single script. First, a user can run the ‘02 Assign Room Occupancy’ script to calculate the number of occupants for each building space. Next, the user can run the ‘03 Get Highest Total Occupancy of Floor’ script to obtain the highest total occupancy of that floor level. Subsequently, the user can run the ‘04 Check Width of Staircase’ script. The width of individual staircases will be checked by extracting the actual run width of the staircase and comparing it with the requirements. The script would also check the total exit width of staircases. The script would acquire a set of data representing a schedule in fire safety regulations to determine the exit capacity of staircases. By utilising the highest total occupancy of floor level and the exit capacity, the script would then calculate the required exit width. The value would be applied to check the total exit width of staircases. The demonstration of compliance results for staircases is shown in
Figure 11.
4.4. Validation of Framework and Prototype
The validation of the framework was conducted to evaluate the experts’ level of agreement on the importance, completeness, and reliability of the framework. The validation results indicate high mean ratings ranging from 4.09 to 4.37 out of 5.00, as shown in
Table 4. All experts believed that the framework has the potential to be implemented as an automated system as a tool to assist designers. One of the experts suggested that the implementation of the automated system could be more interactive, for instance, in a Virtual Reality environment; this would assist not only designers but also clients to visualise the checking process. Furthermore, another expert believed that this could also be used by the fire authority to check the minimum compliance before approving the building design.
All the experts also believed that all operators of the RASE methodology—that is, the <r>, <a>, <s>, and <e> operators—are equally important in interpreting the meaning of each clause. One expert considered the RASE methodology as a means of transforming the conventional form of the clauses into a digital library version; this would give designers a better understanding of the meaning of each clause. All experts stressed that although compliance could be checked automatically, there should be an allowance to alter the final compliance results based on fire safety experts’ judgement, especially for informative clauses.
In the validation process, the prototype’s features and functions were first demonstrated to the experts. Next, the experts were invited to test the prototype through the Dynamo Player in Revit. Subsequently, they provided feedback and filled out the questionnaires. The prototype was validated based on its usability, accuracy, reliability, and improvement to existing practice. The mean ratings for the validation of the prototype were very high, between 4.79 to 4.96 out of 5.00 (
Table 4). High mean ratings for all criteria affirmed that the automated system proposed in this research has a shallow learning curve, is easy to use, is accessible, and is an improvement over the existing manual process. All agreed that the prototype is user-friendly as it operates in Revit without requiring any new software application. The suggestions and feedback were considered in outlining the contributions and limitations of this research, as well as the prospects for future research.
5. Discussions
Although this study adopted the methods introduced by other past studies, this paper emphasised on establishing and structuring the conditions of the methods as well as addressing any limitations that occurred. For the categorisation process, in the original work [
83], the filter system commenced with the first filter categorisation followed by the second filter categorisation. This study introduced a supplementary procedure before initiating the first filter categorisation where clauses containing references to other clauses or regulations should be identified, ensuring that the interrelationship between those rules remain intact. The dependence on other requirements was also acknowledged in another study [
85].
This study also established the conditions for declarative, informative, and remaining clauses. These conditions are presented in
Table 5 along with examples of excerpts from the clauses in the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012. The declarative clauses should be categorised by identifying clauses containing geometrical or definite rules such as the dimension of spacing for seatings and the availability of a fire protection system. For informative clauses, two conditions were established. First, this category should represent any clauses that contain ambiguous terminologies or arrangements. Keywords such as “where appropriate”, “suitable”, adequate”, “as far as practical”, “furthermost point of floor”, and “as may be required by fire authority” are indicators of ambiguity in the clauses. Second, the informative clauses should represent clauses that provide options for designers. For example, the keywords “either”, “or”, and “where practical” refer to the consideration of designers in deciding the best design solution. The remaining clauses should then be able to meet one of the three criteria: explaining the terminology used in other clauses, providing general provisions for other clauses, or providing specific calculation methods for other clauses.
For the decomposition of semantics in the clauses, previous work revealed three limitations of the RASE methodology: first, the relationship between individual rules was absent; second, the <a> and <s> operators created an unnecessary repetition; third, the marking-up process for <s> and <e> operators was redundant [
43]. These limitations were taken into consideration and the conditions were restructured in this study. The first limitation was addressed in the categorisation process, where any clause that contains reference to other requirements should be marked. For the second limitation, in the original work, the <s> operator was applied to mark any phrases containing definitions or alternative terms for <a> marked-up phrases [
16]. Another study argued that the identification of the <s> operator created redundancy as this operator had a similar function to the <a> operator [
43]. Although the redundancy was undeniable, this was not considered a limitation in this study. The identification of the <s> operator was necessary to maintain the originality of the clauses. Differentiating the <a> and <s> operators was challenging as most clauses contain sub-rules; thus, iteration occurred in refining their functions. Therefore, this study established that the <a> operator should be applied to mark the main object in a clause while other objects should be marked with the <s> operator. In the original work, the <e> operator was the opposite of the <a> operator. The definition of the <e> operator was further defined in this study, where it should also be an exception to the <r> and <s> operators. Although previous work identified the <e> operator as redundant, the identification of <e> marked-up phrases should be conducted to retain the interrelationships between the rules.
After the marking-up process, the clauses should be formalised in a tabular manner to identify the topic, comparator, and target value. The original work suggested selecting commonly used terms from a restricted AEC dictionary to determine the topics of the phrases [
16]. Although determining the topics was argued to be too repetitive [
43], it was considered relevant in this study. Since the terms for the topic might vary according to country, the topics should be determined based on clauses or regulations that contain definitions of common terminologies. For example, in the case of the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012, by-law 133 was used as a point of reference to determine the topics of the phrases. To standardise the identification of comparators, <r> marked-up phrases should apply “equal”, “not equal”, “more than”, and “less than” comparators while <a>, <s>, and <e> operators should apply “include” or “exclude” comparators. As implemented in the case studies, the topics, comparators, and target values should be organised to restructure the fire safety clauses. Any exceptions to the rules should also be included in the restructured clauses, improving the restructuring process introduced in the previous work [
41]. This inclusion is vital to preserve the relationship between the main rules and exceptions. In any case where the restructured clauses disclose any discrepancies with the original meaning of clauses, the whole decomposition process should be iterated until accuracy can be achieved.
In the case study, interview sessions were conducted to interpret the informative clauses. From the interview sessions, this study concluded that the informative clauses should be open-ended as these clauses highly depend on the judgement of designers and the relevant authorities. These judgements vary between construction projects, designers’ experience, and jurisdictions in different countries. Thus, an automated system that incorporates informative clauses should allow designers and relevant authorities to override the compliance results.
For the identification of BIM properties, the OmniClass™ classification system should be regarded as a reliable classification system in standardizing the naming of components or building elements. As implemented in the case studies, custom classification systems were built to define the building types and spaces that could be adopted in other regulations. This study provided a proof-of-concept prototype in Revit through Dynamo scripts. Through this method, designers could directly use the compliance results from the Dynamo scripts to rectify their BIM models. Alternatively, the result could be exported into a report by creating Schedules in Revit for doors and staircases. These Schedules could then be exported into Microsoft Excel. The flexibility for users to run the scripts either in Dynamo Player or the built-in Dynamo tool proved that this proposed automated system could accommodate high user accessibility to manage the rules. The development of scripts according to the pseudocode modules demonstrates the separation of rule management and rule execution. Although the proposed system was tested in Revit, the pseudocodes and scripts could be replicated in other BIM software applications.
6. Conclusions and Recommendations
This paper describes a user-friendly approach to developing an automated system for compliance checking in a BIM-based environment. The automated system was implemented on a total of 256 fire safety clauses applicable in Malaysia and validated by Malaysian fire safety experts.
The intellectual contribution of the study is threefold. First, the semi-automated translation process for building regulations addresses the issue of limited involvement from AEC experts in past studies. The overall rule translation process consists of five approaches: categorisation, decomposition through semantic mark-up RASE methodology, interviews with relevant AEC experts, development of pseudocodes, and the encoding process through Dynamo. The combination of these techniques presents the novelty of this study and eliminates the limitations found in existing studies as it encourages greater participation of AEC professionals, compared with software developers. Second, the identification of necessary BIM properties in native file format overcomes the challenges in preparing the model for IFC data. Through Revit file format representation, designers could simultaneously employ the automated system during the design process without having the burden of converting the BIM models into IFC representation. This approach makes it practicable for designers in using the system. Third, the study provides the necessary information to develop BIMSMACC consisting of the BIM properties, a set of pseudocodes, and a prototype in Revit. The BIM properties provide guidelines to designers in equipping their BIM models for compliance checking. The pseudocodes could be considered a digital representation of the fire safety clauses in the Selangor Uniform Building (Amendment) (No 2) By-Laws 2012; they act as a basis for automation of the compliance checking process in a BIM-based environment.
This paper focuses on the implementation of the proposed framework for the compliance checking of BIM models against the fire safety regulations in Malaysia. It was found that while the clauses could be semantically decomposed and interpreted, inputs from designers and the fire authority should not be dismissed in determining the final compliance results. The results are still subjected to the judgement of designers during the design process and to approval from the fire authority. Through the proof-of-concept prototype, this study highlights the main function of the proposed system as assisting the designers and not substituting the responsibilities of the fire engineers. Based on the validation by the experts, the proposed framework and prototype are accurate and reliable.
The limitation of this study includes the research scope, whereby the selected clauses were derived from the Selangor Uniform Building (Amendment) (No. 2) By-Laws 2012. Other regulations such as Malaysian Standards, British Standards, and internal policies by the fire authority were not included during the interpretation process. For the BIM model, the BIM properties defined for this study were limited to the application in Revit only. Another limitation is that due to the subjectivity in informative clauses, the compliance results should be subjected to the judgement of designers during the design process and the local authority’s approval. Thus, it is to be highlighted that the main purpose of this proposed system is to provide a tool in assisting designers and not to substitute the responsibilities of the fire engineers.
Future works include the extension of the prototype to become a comprehensive application that can accommodate all fire safety clauses in Malaysia. Other regulations such as Malaysian Standards and discretionary requirements from the fire authority can also be added to the system. The BIM properties defined in this study could be converted to the IFC data model to accommodate other BIM platforms. The framework could also be extended to other types of building regulations and not limited to the fire safety regulations only.