Over recent years, technologies related to the construction industry have evolved and become more complex. Given that buildings are constructed by combining several parts and products, construction is generally affected by developments in several technical and product fields. In particular, the developments in fundamental technologies, such as arithmetic processing and communication technologies, represented by computers and the Internet, respectively, influence a wide range of building construction methods in a complicated manner, given that these approaches are used to produce several building-related products and parts.

The 2020 pandemic has highlighted the need to update several aspects of the building industry, such as building demands, planning ideas, and construction processes, including the supply chains. In particular, owing to the difficulties faced by people in moving across countries and the increase in remote work and video conferencing, the perceptions of physical distance have changed. Consequently, although working physically at a workplace will continue, it is believed that processes such as design sharing and component production could be conducted through video conferencing systems. Furthermore, it is believed that virtual meetings are likely to increase in the future. Therefore, building construction process trends within and across areas are changing simultaneously.

Considering this, it is important to understand the characteristics of the building industry in all regions to recommend the future direction of construction systems while making the best use of the changing characteristics. However, each project is implemented considering various factors, such as the site conditions, surrounding environmental conditions, client requirements, and legal situations in the area, thereby making it impossible to develop unified standards across the industry.

Therefore, this study aims to develop a method to describe the characteristics of building construction in all regions by considering the characteristics of the building industry based on industrial analyses and by providing a new perspective on practical building industry analyses using the “architecture concept.” The architecture concept considers the design concepts that form the basis of an artificial system, and its fundamental principle is the system concept, commonly used in designing complex artifacts, including engineering products [1, 2]. Several industries have already been analyzed using this concept [3-6], based on the idea that the functions of a system, wherein the elements are connected, correspond to the structure of the system. It is fundamental that the process corresponds to the structure to create artificial objects, such as products and services, considering the purpose of realizing the functions of the target system using the designed structure. This concept encompasses several aspects created for buildings and spaces and is considered to have a high affinity toward the building industry [1]. Furthermore, several studies have been conducted to understand the characteristics of various industries with this concept [5-7].

Using this concept, one can consider the product and process architectures that target the structures and functions. This study mainly focuses on examining the product architecture to help understand the industrial characteristics of the building industry in each region. To this end, the product architecture is described and expressed clearly.

Architecture is created with different conditions such as site conditions and owner's requirements therefore it is quite difficult to compare all architectural projects simultaneously. Furthermore, architects and builders have their own ideas about design. Moreover, it cannot be denied that each region or country has its own tendencies toward specific architectural designs. Therefore, this study focuses on 'standard details' that clearly express the design thought tendencies of the designers in each region. This approach is rarely used in the research of the construction industry and can be academically considered a novel attempt.

Researchers from different fields have challenged the description of industry characteristics and conducted discussions to understand practical corporate activities and client situations. However, most previous studies using the architecture concept have targeted mass-produced products, such as automobiles, computers, and electronic components [6, 8-10].

Typically, the concept of architecture has two indexes: “modular–integral” and “open–closed” [5, 8]. The “modular–integral” index is based on the interface between elements [5]; that is, if the system is an “integrated architecture,” the design rules of the interface must be coordinated with each other and the system must be tuned to maximize its potential performance [8, 11]. Conversely, the “modular architecture” provides a standardized interface for linking different components and modules [7, 12]. Therefore, independent components can be combined to manufacture various systems, provided they are compatible with these standardized interfaces. Although modular architecture maintains the independence of each module and accelerates the evolution of the system, the standardization of interfaces between the modules limits the overall performance potential of the system [5, 13].

Modularity can be classified as open-type or closed-type [8, 12]. “Open architecture” is a type of modular architecture with an industry-standard interface that enables the collection of parts and modules across enterprise and product boundaries. Modular architecture simplifies interface design information. The open-closed index is an important parameter, especially for designers of products with mass production. Several researchers have studied the modularity and integrality of such mass production systems [6, 13-15]. One important advantage of system modularity is that the commonality of components can allow for the use of various products from multiple markets [5, 16]. Although a clear distinction exists between structure modularity and process modularity [17], many previous studies have focused on modularity as a structure based upon static views [13, 18, 19]; by contrast, process modularization has not received much attention. In many industries, designing a standardized interface for a process is not considered important. The advantage of process modularization is that the designer can design a product within a module [6]. Consequently, several companies are attempting to modularize the structure of their products for competitive advantage [20, 21]. However, every company requires a significant amount of knowledge and information to ensure component compatibility and to implement mutual coordination [22].

Previous studies have discussed the relationship between the modularity of the creator's organization and the product structure when a product is created, also known as the mirroring hypothesis [23]. Based on this hypothesis, products with modular structural architectures are devised by organizational capabilities, which tend to be modular design ideas [18, 24, 25]. Each organization may design a product with a modular structure based on specific conditions. Therefore, it is essential to study the cause of the modularization of the structural architecture of the products [20]. If the manufacturing organization is modular, the structural modules of the product can be made compatible by establishing an interface in the structural architecture of the product [26]. Furthermore, restructuring the organizational units can potentially create highly effective inter-organizational interfaces and facilitate effective collaboration [25, 27]. However, previous studies have been unsuccessful in clearly explaining this mechanism because they did not entirely focus on the ability of organizational unit structures and interfaces to facilitate the modularization of the systems being created. Moreover, the dynamic relationships are unclear, making it difficult to understand the overall creative mechanism.

Sharing knowledge between organizations can be facilitated by providing and receiving information regarding specific tasks. In such cases, knowledge sharing between multiple organizations involves collaboration to develop creative processes and product concepts [28], given that this can significantly impact product and new technology development and also problem solving [29]. Furthermore, it can promote knowledge sharing through communication between the designers and engineers of other organizations [30, 31].

The relationship between the characteristics of organizational ability and knowledge sharing has attracted wide attention [32, 33]. In many cases, sharing of critical knowledge can be understood as the process of creating different types of relevant information [34]. Some studies have stated that organizational ability can be achieved by sharing [32] and transferring knowledge and design information [33, 35]. Organizational capabilities are based on the constantly changing internal and external environments, and these capabilities must be continuously upgraded [36, 37].

Inter-organizational interfaces, which are important for knowledge sharing in multiple organizations, are recognized as mutually coordinated platforms [38-40]. However, previous studies have not been able to adequately identify the appropriate combination of elements necessary for creating an effective inter-organizational interface. Therefore, it is important that the factors and mechanisms effective in creating efficient organizational interfaces are analyzed for knowledge sharing as these factors and mechanisms have a significant impact on the organizational structure and the modularity of the system thus created.

A good understanding of the modularization process of a system can improve the understanding of the characteristics of the system, considering that it affects the degree of modularization [7, 17]. However, it is difficult to understand the modularization process entirely as it includes technical aspects, along with the organizational aspects, such as the interaction between organizations and information sharing by multiple organizations [41, 42].

In addition, there have been only a few technical discussions on modular construction projects [43-45]. Modular construction can potentially decrease project complexity and the time and cost associated with engineering development while also increasing construction productivity. The characteristics of the project and individual technologies have also been discussed. Specifically, previous studies have discussed the technical possibilities from the perspective of mass customization [46] and practical consideration of interfaces [47]; most of these studies aimed to reduce the complexity of the construction industry. However, studies discussing the characteristics of the industry or region have not been reported thus far.

Therefore, this study presents concepts for understanding the regional characteristics of the construction industry. The complexity of the construction industry, the large number of parts, and the breadth of the related technical areas suggest that careful consideration of structure is required, as compared to other industries. Moreover, each project was conducted under specific conditions, including regional conditions. Through our study, we believe one can acquire a deeper understanding of the regional characteristics of the construction industry while focusing on other issues. The technical characteristics of the construction organization in each region have been described, given that the characteristics and availabilities of the organization affect the product architecture. A better understanding of the unique product architecture pattern of each region can result in a better understanding of the aspects of the technical characteristics of each region. Moreover, although the production process is important, it is difficult to completely clarify the process based on previous studies. Therefore, this study focuses directly on understanding the characteristics of the completed structural system instead of the process.

Based on the architecture concept mentioned in the previous section, we examined actual construction technologies as a case study. Initially, this study focused on multiple regions to understand their different characteristics in terms of distance and culture. In particular, only two regions, Europe and Asia, were analyzed at first, considering that this is new research in the construction field. Thereafter, we targeted areas that had less direct influence than other areas owing to their maturity in the technical aspects of construction. Furthermore, we considered the high technical maturity of other industrial areas based on international competition and the possibility that certain strengths and weaknesses have been established in each region [8, 48]. Lastly, we assumed that the construction industry of the target area tended to be independent of the other areas because of law, language or logistics, etc.

As it was necessary to ensure reproducibility and objectivity, we assumed that the same study could be performed for the building technology in any region. Thus, this study developed into a comparative study of the construction industry by considering only two regions; nevertheless, previous studies were also considered to enable the reproduction of the same study for the other industries in many regions [5, 6, 45, 49].

Herein, we conducted a case study in the UK and Japan while considering the above-mentioned points. The two regions are geographically separated by the sea, have a clear boundary with their surroundings in terms of regulations, are highly independent of their surroundings in terms of the flow of people and goods, and are technically mature. Therefore, surveys in these two areas were deemed suitable to meet the above-mentioned conditions.

However, all construction projects are planned under unique conditions (such as the purpose, main use, owner's requirements, and site conditions). Therefore, it is difficult to establish the characteristics of each region by comparing projects individually. Additionally, given that a building comprises several components, it is difficult to understand the overall trends immediately. In summary, each building is original and enormous and also comprises several elements, thus making it difficult to understand the technical nuances of the construction industry.

However, one can observe the flow of the construction design methods to understand the trends. During building design, there is a mechanism to deal with the size characteristics and a large number of elements. Many organizations in the same area share standard ideas concerning architecture. Therefore, it is important to develop an accurate budget and construction schedule when planning a project. However, being active in the same region makes it difficult to notice the diversity in thinking pertaining to other areas.

Therefore, this study focuses on the “standard details” established based on the region. Consequently, it may be possible to understand the characteristics of each region by comparing the composition of elements in the standard details in order to retain the interdependence of elements.

We compare the points at which elements of the building physically overlap and explore the standard details of particularly complex areas. Specifically, we focus on three primary sections, which are located around the foundation, opening, and parapet, where construction structures and finishes overlap frequently. These are the points of contact between the outer wall (vertical structure) and floor slab (horizontal structure), and they contain numerous complex elements. The foundation is in contact with the ground, the opening comprises many window frames and sealing components, and the periphery of the parapet is influenced by the parapet and waterproof layers. Considering that these three sections have multiple functions requiring advanced technologies, such as waterproofing and sound insulation, their production would necessitate additional technology, components, and processes, as compared to the other parts of the building. Therefore, in most projects, architects and designers study the standard details of these three highly complex sections mainly, and these parts of the actual building are built using these standard details.

This section describes the product architecture for the standard details of complex parts in the UK and Japan in order to clarify the design concepts considered for these parts. Subsequently, we examine the possibility of determining the technical characteristics of each region using this method.

4.1. Description of Product Architecture

This section describes the typology of interface design ideas based on the basic indicators, according to the standardization of the interface and the contacts of related components. Specifically, the following three design ideas, which are considered to be similar, were examined. The first focuses on the form, materials, and parts of the interface being standardized. The second examines the need for fine-tuning around the interface at the construction site. The third focuses on the standardization of the form and installation methods of the related components.

4.1.1. Standard Details of the Rise on Baseplate

Although the rise on a baseplate is one of the most complicated parts of construction technology, it is possible to identify clear differences between the Japanese and UK standard details (Figs. 1-3).

Fig. (1). Standard detail of the rise on a baseplate (Japan) [50].

Fig. (2). Product design thinking for the standard detail of the rise on a baseplate (Japan).

Fig. (3). Standard detail of the rise on a baseplate (UK) [51].

In the Japanese standard, all elements, including the small parts, are integral, especially for waterproofing (Fig. 2), considering that the baseplate has a slanted surface. However, the interface is not standardized. The interface part is constructed and customized according to the surrounding shape and material. In other words, each component is not standardized and is instead customized via fine-tuning based on the surrounding components. Most Japanese standard details are built using an integral design concept. By contrast, the UK standard detail only includes a few integral elements (Fig. 4).

4.1.2. Standard Detail of the External Wall Opening

Many technological construction elements exist around the opening in an external wall, particularly for window systems, which comprise several elements and parts (such as windows, casings, sills, and aprons) (Figs. 5 and 6). Therefore, the integral element types can be determined anywhere in the Japanese standard detail of this part, which encompasses high-level waterproofing systems (Fig. 7). However, there are only a few integral parts and elements in the UK standard detail (Fig. 8).

Fig. (4). Product design thinking for the standard detail of the rise on a baseplate (UK).

Fig. (5). Standard detail for the opening in an external wall (Japan) [50].

Fig. (6). Standard detail for the opening in an external wall (UK) [51].

Fig. (7). Product design thinking for the standard detail of the opening in an external wall (Japan).

Fig. (8). Product design thinking for the standard detail of the opening in an external wall (UK).

4.1.3. Standard Detail for Asphalt Roofing

The most complicated part of asphalt roofing is the edge of the asphalt sheet, surrounded by many elements (Figs. 9-11). In the Japanese standard detail, all upper-level elements are combined with the integration of the lower-level elements (Fig. 10). However, in the UK standard detail, all the elements are developed using a standard combination with the lower-level elements (Fig. 12).

4.2. Description of Product Architecture and Functional Architecture

It is possible to understand the relationship between the functional and physical structures of artifacts [5, 48], which indicates the characteristics of the design thinking for each system. Compared to integral systems, wherein one physical part serves several functions, the physical part of a typical modular system only has one function. Moreover, one function is associated with one physical part in a modular system and several physical parts in an integral system.

Fig. (9). Standard detail for asphalt roofing (Japan) [50].

Fig. (10). Product design thinking for the standard detail of asphalt roofing (Japan).

Fig. (11). Standard detail for asphalt roofing (UK) [51].

Fig. (12). Product design thinking for the standard detail of asphalt roofing (UK).

Ulrich presented an example using trailers, as shown in Figs. (13 and 14) [5]. Fig. (13) demonstrates a chart created using the modular design concept. The function and structure exhibit a one-to-one correspondence; that is, each module has only has one function. In this case, the development, design, and production of each module were performed on a module-by-module basis thus it is difficult to find functional integration.

Fig. (14) shows an example of a chart created using the integral-type design concept, wherein the relationship between the functions and the structure is more complicated. Therefore, it is difficult to develop and design parts individually, as compared to designing the entire system. On the other hand, this approach is advantageous in terms of improving the overall performance. Consequently, the design concept can be understood by focusing on the relationship between the product and the functional architectures.

This section describes the product and functional architectures with reference to the description method. The description subjects are the three complex standard details, as mentioned in section 4.1, that express the technical characteristics of the UK and Japan systems.

Fig. (13). Example of the mapping of functional elements to physical components (modular type) [5].

Fig. (14). Example of the mapping of functional elements to physical components (integral type) [5].

4.2.1. Standard Detail of the Rise on Baseplate

Product design thinking involves several complicated elements (Figs. 1 and 3), and it is important to understand the structure of the physical elements and functions.

Based on the description of the product and function design thinking (Figs. 15 and 16), the difference between the Japanese and UK standard details can be determined. The Japanese system tends to be integral in terms of design thinking, whereas the UK system tends to be modular. For example, there are several complicated integrations involving waterproofing and insulation functions in the Japanese details, whereas the UK system simplifies the same.

4.2.2. Standard Detail of External Wall Opening

Although the external wall opening functions are complicated (Figs. 5 and 7), each function is important for the fundamental building quality, such as in terms of waterproofing, noise insulation, and lighting.

Figs. (17 and 18) present the descriptions of product and function design thinking for the external wall opening under the Japanese and UK systems, respectively. In the Japanese system, many elements are used to establish the functions. For example, the functions of pressure resistance and withstanding loads are based on many elements. By contrast, the relationship between the physical parts and functions is simple under the UK system. For example, in the UK system, casing and internal finishing are performed to improve the esthetic design, whereas, in the Japanese system, casing is an important element for noise insulation, pressure resistance, and waterproofing, among others.

Fig. (15). Mapping of functional elements to the physical components of the standard detail for the rise on a baseplate (Japan).

Fig. (16). Mapping of functional elements to the physical components of the standard detail for the rise on a baseplate (UK).

4.3.3. Standard Detail for Asphalt Roofing

Given that waterproofing is the main function of asphalt roofing, it is established by employing many elements and parts in both systems.

It is possible to identify different details around the edge of the membrane used in both systems (Figs. 19 and 20). Numerous elements are used to design details around the edge of an asphalt membrane in the Japanese system. However, the details are quite simple in the UK system, comprising only a few elements. The details of insulation are almost identical in both systems, although there are many physical elements in the Japanese system. The insulation quality of the Japanese system is better than that of the other system, although there are certain drawbacks concerning the cost and terms of construction.

Fig. (17). Mapping of functional elements to the physical components of the standard detail for the external wall opening (Japan).

Fig. (18). Mapping of functional elements to the physical components of the standard detail for the external wall opening (UK).

Fig. (19). Mapping of functional elements to the physical components of the standard detail for asphalt roofing (Japan).

Considering the rapid technological developments and global pandemics, it is necessary to understand the characteristics of the building industry in each region in order to recommend the future directions of the construction system such that regional characteristics are used optimally. However, the notion of a project's relativity does not help develop a discussion. Therefore, this study developed a method to describe the characteristics of building construction in each region.

The “architecture concept” was used as a tool to focus on the interdependence of the components to be created and analyze the design information created by designers and engineers in the UK and Japan. This concept clarified that the UK and Japan followed the modular and integral characteristics, respectively, for the fundamental design concept of construction.

By analyzing the trends of the unique fundamental design concepts in the two regions pertaining to building construction through case studies and discussions, we developed a perspective regarding the characteristics of each region. The main aim of this study was to develop a method to understand the characteristics of the construction industry in different regions. Specifically, this research proposed a method to describe product architecture and the relationship between the product and functional architectures of the construction industry using the architecture concept.

The results of this study showed that the characteristics of the construction industry, such as the complexity of individual production, diversity of participating industry areas, diversity of participating technology areas, and regionality of rules, can influence the design concept during product creation. However, this study only discussed the possibility of describing the present construction techniques in two regions. Hence, it is necessary to understand the important points. For example, if the fundamental conditions change (fundamental development of technology or potent alteration of regulation etc.), the modular design concept would be transformed to the integral design concept, thus influencing the architecture dynamics [55]. Due to their lack of understanding about modularization and the creation of interface rules, designers prefer to have integral-type design concepts at first. However, the modular concept should become mainstream as organizations seek to reduce the invested economic resources (such as development costs, development time, and production costs). As mentioned above, the construction industry has been established through the participation of many technical and industrial fields. Therefore, technological innovations and changes in other industries can significantly affect the technologies pertaining to the construction industry.

For such inter-regional and inter-industrial comparisons, increasing the number of research targets, including construction standard detail in other areas and design information in other industrial fields is essential in the future.