*4.2. Main Building Trades and Interfaces in Hospital Construction*

This section focuses on the various building trades and disciplines that need to be taken into account in hospital construction to avoid collisions and interface issues, according to the experts. Besides the typical collisions of the building trades of heating, ventilation and air conditioning (HVAC), as well as sanitary services and electricity, the experts have reported on many other interfaces in hospital buildings, which occur in view of high safety requirements of fire protection and hospital hygiene. Furthermore, medical and laboratory technology represent another challenge in terms of early and precise planning. In this context, it is important to ensure that reserves are planned so that dimensions and ports suffice in the event of change or replacement in equipment. Electrical engineering is one of the largest building trades involved, which requires precise planning of cable routing in coordination with the technical building equipment. A list of the most important disciplines is shown in Figure 3.

Based on the evaluation of the interviews, the main interfaces of measures in hospital construction are summarised in Figure 4, as follows.

#### *4.3. Impact of Interfaces Using the Example of Doors*

According to the experts, decisive components with high coordination efforts are the doors located in the corridors. Due to the requirements of the necessary functionality in running a hospital, these are an essential element and example of the undisturbed operational flow. Doors have high demands on fire protection and access restrictions and need to be planned and executed by different trades. For electrically operated doors, this includes the door itself, the supply line, as well as the internal wiring for controlling the

door, provided by electrical engineering. An exemplary structure of an automated door system with access restriction is shown in Figure 5.

**Figure 3.** Integral technical planning in hospital construction (own illustration).


**Figure 4.** Evaluation of the main interfaces and collisions, which are marked with an "×" (own illustration).

Due to the large number of planners and trades involved, this is where most of the interfaces arise, and particular attention is needed during the planning phase. According to the experts, in conventional planning, some services, such as the supply line of the doors, are forgotten to be tendered, which is only noticed during execution. Consequently, a supplement is issued, which considerably increases the additional costs due to the large number of doors in a hospital.

Another difficulty is that doors are usually components with high fire protection relevance. Doors along escape routes must be able to be opened manually in the event of

fire, but they also protect against the spread of smoke in the building. Moreover, automatic opening is often required for hospital operations because patient transport in beds is part of everyday operations, especially in the corridors. Furthermore, it is necessary to consider functional areas, which may only be entered by personnel using access authorization. In this area, doors must be installed in a manner that allows them to be opened in the direction of the escape route at any time, even without the electrical presentation of authorization. In the event of fire, the doors must be able to be opened from both sides without the electrical presentation of authorization. For this reason, the wiring and the direction of installation must be considered during installation. Card readers for checking access authorization need to be installed in the immediate vicinity on the correct side and connected to the door.

**Figure 5.** Structure of an automated door system with access restriction. (Adapted with permission from [31]. 2020, Dormakaba Group.)

#### **5. Solution Approaches**

#### *5.1. Application of Digital Methods*

The implementation of digitalization in the projects of the interviewed experts varies. On the basis of the expert interviews conducted, assuming that interfaces can be reduced by means of digital planning, it was analyzed whether the options listed below can lead to a reduction in interface problems.

#### 5.1.1. Impact by Application of BIM

The BIM method is considered a pioneer of digital planning. In terms of hospital construction and the many different and complex interfaces, BIM is a suitable tool for reducing interface problems. If applied consistently, a BIM model contains all project information and keeps the data centrally in a browser- or cloud-based project space, a so-called Common Data Environment (CDE). The information attached to the individual building components simplifies the calculation of quantities and costs, e.g., by determining the number of necessary fire compartments directly from the model. This is a significant advantage, especially in hospital construction, due to the complex requirements for ventilation technology. It also simplifies the exchange in data between the stakeholders and ensures that everyone is on the same planning level to minimize the number of design errors due to a lack of communication. As a result, problematic interfaces and collisions can be identified and rectified in the early stages of planning. In a further part of this article, it is described how earlier handling of planning errors has a lower impact on costs than if it would be remedied at a later stage of planning (Figure 6).

**Figure 6.** Effort of traditional planning and planning with BIM, according to the MacLeamy curve (own illustration based on [32] (p. 32)).

BIM also offers enormous advantages for facility management. With a digital twin, an economical and effective operation in a hospital can be facilitated. The main advantage of a digital twin can be seen in the aspect of a central data source to which everyone involved has access. With the right management, all necessary data are always available and upto-date, so that the necessary information is available at all times in the event of repairs, maintenance, and servicing measures. However, continuous adaptation and updating of the model is necessary, already, in the operational phase. Moreover, a BIM model can only be used successfully under the condition of fixed collision rules and project-related definitions in close consultation with all stakeholders. This is performed through the elaboration of the so-called Employer's Information Requirements and the BIM Execution Planning, in which the exact procedure for using BIM in the project is described. However, these procedures are out of the scope of the present paper.

The implementation of the BIM method in Germany entails several obstacles, as revealed in the interviews. One significant problem is the lack of specifications that define the remuneration and costs of BIM services. It should also be considered that procurement costs are initially incurred for IT, as well as for the qualification of staff to use BIM. Accordingly, some hospital operators have been rather critical about the implementation of BIM so far. Furthermore, it was criticized that the actors involved in the planning process assume a higher than necessary planning effort. In contrast to the conventional method, there is no increased total planning effort with BIM, but efforts are shifted to earlier sub-phases before execution (see Figure 6). By shifting the effort into earlier project phases, the costs of unforeseen planning changes will be kept lower compared to later changes because the gradient of the cost of changes increases during the progress of the project.

Despite the positive influence of BIM on the coordination of construction projects, disruptions, such as delays due to delivery bottlenecks or unforeseen events, are still possible. Furthermore, the use of BIM creates new digital interfaces, which must also be coordinated in the already mentioned Employer's Information Requirements and the BIM Execution Planning. In the event of occurring planning errors, the stakeholders often refuse responsibility, which ultimately leads to legal disputes. These disputes can only be reduced by clarifying responsibilities at an early stage, e.g., by applying the BIM methodology.

#### 5.1.2. BIM Use Cases

In the further course of this chapter, further digital use cases are described in order to reduce interface errors, whereby BIM constitutes a prerequisite for application. By means of checking design variants, different technical concepts are examined at the beginning of the planning regarding the investment costs. Thereby, functional influences are focused and constitute the basis of the examination for selection of the most economical variant. This is carried out in the early planning stage to determine the demand and is expected to result in an increased degree of cost and schedule certainty, as well as faster commissioning. In addition, it is possible to efficiently design and optimize the routes between the functional areas using a variant check. Operational concepts of, for instance, fire protection officers or hospital hygienists, are to be examined individually by the various professional actors regarding their feasibility and economic efficiency. Furthermore, the functional plans and designs need to be checked for compliance with current regulations in order to identify collisions or planning errors before the start of construction works.

So far, according to the interviewees, a major part of the variant checks is still carried out based on two-dimensional plans. Due to the high number of plans and concepts, as well as the complex planning requirements, it can be assumed that errors may be overlooked, despite a variant check, leading to collisions during execution. A possibility for improvement is the application of the BIM methodology, which ensures that there is only one model with all designs and information to check.

Another possibility to detect planning errors is to carry out simulations during the planning phase. The most common type of simulation involves energy considerations, e.g., to specify heating and cooling cycles. Simulations can also improve the efficiency of the planning of ventilation systems. By visualizing the architectural geometries, pipe routing can be planned and checked for economic efficiency. Another advantage of testing different geometries stands out in fire protection planning. In this way, smoke development in the event of a fire can be simulated and contained with suitable measures. If a preliminary check takes place by means of simulations, it is possible to simulate routes of insertion for medical equipment, as well as of technical systems to eliminate possible complications during planning and to adjust the dimensions. In this context, the simulative preliminary test of the so-called "active principle test", which is relevant in Germany under building regulations, is referred to. It is used to test the interaction of different technical systems in the event of a hazard.

However, up until now, simulations are often carried out with conventional software due to a lack of a BIM implementation strategy. By using the BIM methodology, there are further possibilities, in addition to the advantages mentioned above, to improve planning and construction site work processes and to represent them in an enhanced degree of detail. Virtual reality (VR) can be used to create computer-generated, interactive environments that can be displayed in real time with terminal devices, such as VR glasses, tablets, or smartphones at no great financial expense. The combination of an existing three-dimensional model with VR enables variant considerations, preliminary tests, and collisions to be displayed and checked more clearly. Special attention is paid to the flow of logistical processes. In this way, fire protection concepts, escape routes, traffic routes, or even logistical effects of construction measures can be visualized and adapted in advance.

Starting with fire protection concepts and the planning of escape routes, simulation, in combination with VR, can be useful. In the past, fire protection measures were only tested in their technical function in order to be able to exclude functional errors in the equipment. By visual inspection of the building, escape routes can be viewed in their entirety and checked regarding their stability in the event of a fire. The use of VR also provides a visualization of the development of fire and smoke, which makes necessary adjustments to the fire protection systems visible.

In addition, the traffic and transport routes must fulfill a multitude of constructional requirements. Due to the high number of these routes in a hospital, a manual check is unfeasible. Using a virtual passageway, routes, door widths, room heights, area requirements, lighting, and markings can be checked. Especially, door and corridor widths must be checked with regard to bed transport or accessibility. The introduction of new medical equipment can also be simulated at an early stage using VR, so that problems with insufficient door widths can be rectified before delivery. VR can be also used to visualize

the planning for laypersons so that hospital specialists can check whether all necessary connections and equipment have been taken into account.

Construction measures during ongoing hospital operations always have an impact on the supply and functioning of a hospital. To keep these effects to a minimum, construction measures are demarcated with dust protection walls. By using virtual simulations, the effects can be determined in advance so that measures can be taken to protect patients in advance. In summary, the use of VR aims to optimize processes and to eliminate planning errors and collisions, with minimal effort at the beginning of planning, to avoid delays, to reduce additional costs, and to enforce efficient and comprehensible workflows.

While VR completely replaces reality with virtual sensory impressions, AR aims at a computer-supported extension of reality perception, where the view of the real environment is supplemented with computer-generated superimpositions. By overlaying virtual and real points, visual information, the location of components, and the positioning of reference points on the building, construction experts and laypersons can use visualization to initiate potential changes. The application of AR is not specific to a project phase and can be implemented throughout the entire building life cycle. During the planning phase, the use of AR allows representatives of different trades to view the BIM model from different perspectives. Models can be analyzed more efficiently, and potential problems can be identified by showing and hiding single units. Furthermore, the superimposition of design models, such as a technical building equipment model, with reality, enables early detection of conflict points, which can be rectified before construction work begins.

It is further possible to check and record the current status of construction by overlaying planning models with scan models of the building object. In addition, changes and construction deviations can be checked and imported back into the model to obtain an as-built model at the end of execution. In addition, the use of AR offers the option of projecting plans onto building components, e.g., in order to be able to show pipe to avoid damage during construction. Additionally, it may prove to be useful to prevent execution errors due to the attachment of components or the preparation of breakthroughs with the help of the exact visual specification.

In addition to the advantages of AR in the planning and execution phase, the possibility of virtual representation of the as-built model serves to simplify maintenance, repairs, and servicing measures in the operational phase. By feeding back the manufacturer information of maintenance-relevant components into the BIM model during the construction phase, an automatic maintenance report of the objects can be created, which reduces the workload of facility management. Maintenance technicians can then be sent to the corresponding object and quickly identify it using indoor navigation via AR glasses. This creates huge potential for reducing maintenance working hours by linking virtual step-by-step instructions to the maintenance-relevant components. In the future, there is the possibility of being able to practice standardized work steps by combining them with artificial intelligence and, thus, reducing costs with the help of standardized and routinized processes.

The digital applications mentioned above serve the communication of the project participants across the entire life cycle. Using the virtual models, location-independent meetings with a view of the construction project can be realized. Thereby, cross-trade problems can be discussed rapidly without tedious coordination effort. In addition, the use of visual forms of representation is recommended regarding visits to authorities, as well as citizens' initiatives. By overlaying the construction status with relevant information from the BIM model, use cases can be viewed together on the construction site or in the office. Particularly, with regard to the public purchasers in hospital construction, as well as the many complex requirements and conditions, the possibility of an uncomplicated joint consideration of critical points is enforced. Furthermore, due to the many necessary agreements with the various parties involved and users from other disciplines, a virtual view of the planning represents a great benefit in order to view the interactions of emerging projects in their environment and to contribute to the design.

In summary, with digital methods, such as BIM, many interface problems, such as geometric collisions, can be minimized. However, interdisciplinary tasks for the execution of construction are, at this point, difficult to coordinate.

#### *5.2. Development of a Task and Trade Control Matrix*

Due to the high level of complexity and the large number of stakeholders, but also for user-specific coordination adapted to the building, there is a need for technical and contextual coordination. Based on the findings from the expert interviews, a trade control matrix is considered a suitable tool, especially for hospital construction. Within the framework of the present study, a first draft of such a matrix was developed, which is illustrated compactly with reference to relevant information.

Up until now, control matrices have only been used for safety-related functions and their functional correlation, e.g., as a basis for the active principle test of technical equipment. The intention is to assist specialist planners, building owners, and operators, as well as executing companies, in keeping an overview and being able to present hazard scenarios. At the beginning of the planning process, a risk analysis is performed to determine possible and probable hazards in terms of their use and environment. The risk assessment must be continuously reviewed and updated throughout the entire life cycle of a building.

For the purpose of this paper, the principle of safety control matrix is transferred to the entire construction project and its stakeholders for an optimization of planning and execution. Thereby, the control matrix should be applied and updated by all stakeholders in each project phase. The associated advantages are demonstrated through clear definition of the interfaces and the corresponding responsibilities, which facilitate coordination and reduce errors in planning and execution. The precise demarcation of interfaces clarifies who is responsible for and involved in which part of the construction measures from the beginning. Nevertheless, should errors occur, those responsible can be clearly identified on the basis of the task control matrix. Another advantage of using a task and trade control matrix becomes apparent in construction supervision. Site managers and project controllers obtain an improved overview, with all the necessary information compactly summarized and organized. Furthermore, executing companies obtain more insight into their areas of responsibility and can schedule their work more easily.

A task and trade control matrix was created with specification of the building trades involved in hospital construction (compare Figure 7). In this context, it should be noted that only the main building trades are listed in this figure for simplification. As participants vary in every project, they need to be adapted specifically. In addition, heating, ventilation, and air conditioning are grouped together for a simplified illustration; likewise, the executing trades in building construction have been kept general and are to be adapted to the corresponding building component.

By specifying the trades involved and naming the subcontractors and their contact persons, an overview of the distribution of tasks and responsibilities can be created. Specifying the location of the components helps to further enable a direct assignment of the corresponding component. In this way, the division of tasks for a construction service can be applied to a large number of identical components. The matrix merely needs to be multiplied and related to its respective component. Subordinately, the construction work can be divided into its sub-services, so that an exemplary checklist for an automated door system with access restriction is created based on the fundamental requirements elaborated through the literature research and the expert interviews (see Figure 7).


**Figure 7.** Exemplary task and trade control matrix using the example of an automated door system with access restriction (own illustration).

Ultimately, the approach of a task and trade control matrix pursues the intention of developing a standardized processes for construction services and creating generally applicable interface catalogues that can be used for future construction projects. Using this task and trade control matrix, interfaces can be delineated at an early stage, thus reducing possible planning errors. By linking it to a construction schedule, supplements, disputes, and the resulting extensions to construction times to complete construction measures are reduced. In addition, it is possible to link the component-specific task and trade control matrix directly to the respective objects in the BIM model in order to visualize the state of execution. By programming the matrix of a component, it can be linked to the same component of the object and catalogued in the BIM model and identified by its location. By selecting the location of the respective component in the matrix, the correct object is highlighted in the model. The query about the status of the construction is then made based on the matrix and can be displayed in the BIM model. Thereby, a laborious search for the appropriate component in the model can be avoided, and the status of the construction work can be queried individually for each component.

Lastly, the virtual representation in the BIM model makes subtasks clearer. If this option is further combined with the possibility of VR / AR, the components can be viewed directly on the construction site or in the office. Thereby, responsibilities can be better represented and more easily documented in meetings with the stakeholders. Additionally, transparency is created regarding the construction work and its subtasks, by which the stakeholders have both a written description of the work and a visual image from every perspective. As a result, ambiguities can be minimized, and execution errors can be avoided.

#### **6. Conclusions**

The planning and execution of hospital buildings is highly complex due to the numerous requirements described. Using BIM in connection with a CDE, communication can be improved and become more transparent, which is indispensable for complex construction projects. More efficient results can be achieved through a regulated flow of information regarding the timeline and content. As a prerequisite for the application of BIM, all stakeholders need to possess the necessary software programmes and have the appropriate software knowledge and basic knowledge of the BIM application. Furthermore, the project participants should use an exchangeable format, such as Industry Foundation Classes (IFC), to fully exploit the potential for communication. Accordingly, the openBIM approach is explicitly recommended for handling.

Furthermore, the use of BIM as the basis for processing of integral building planning enables recognition and elimination of interfaces and collisions at an early stage. Due to model-based data, BIM also provides the opportunity to carry out simulations, such as the spread of fire and smoke or the evacuation of a building, to perform necessary changes early on. After all, the later interface problems are identified, the greater the impact, since the cost of change increases exponentially over the course of the project. Planning errors can be identified through automated model-based checks with BIM. However, for the identification of interdisciplinary interface errors in construction, the use of a task and trade control matrix is recommended, in which the interfaces and responsibilities are demarcated, leading to a decrease in the potential for interface errors. The intention is to link BIM models to the matrices, so that they can be assigned to the respective objects in the digital model. Although the solutions presented in this report were created based on hospital construction, they can be transferred to any other building type. Especially complex projects can benefit from this approach, as the described challenges and risks are particularly important to clearly define the interfaces. Nevertheless, an adaptation of the tasks and trades in the matrix is necessary for different building types and for each project. Furthermore, it is important to mention that the developed solution approach in this present study has not been piloted. In future, the application of the task and trade control matrix in connection

with BIM needs to be examined in a pilot project, and the results need to be reflected and, if necessary, adapted. The benefits and effort are to be analyzed.

Notably, the German regulations are not yet adapted to the application of the BIM methodology. Since the introduction of the BIM method cannot be simplified by adapting a single set of rules, a considerable amount of adaptation of the legal framework in the construction industry is required. Besides the fee schedule, public procurement law, and contract design, the question of liability needs to be clarified. Especially, in hospital construction, many legal regulations must be taken into account, which are interrelated. An additional complicating factor in Germany is that many requirements must be observed and laid down in different laws and regulations, and, thus, they differ partly in the various regions of Germany. Therefore, based on the results of this work, the need for a specialized digital directive in hospital construction for national application is expressed. This should simplify the construction process regarding the merging of hospital construction guidelines and ancillary rights and present them more clearly.

To ensure the optimization of construction projects in hospitals by using BIM, strategic change management must be established in the construction departments of the hospitals in order to qualify the staff accordingly. To spread and promote the use of BIM in hospital construction and to maximally exploit the advantages of BIM, clear recommendations for the use of BIM should be formulated. Accordingly, an application-oriented guideline for the step-by-step implementation of BIM in hospital construction projects is required. The guideline should describe an adequate BIM strategy with potential use cases based on the complex requirements and framework conditions in healthcare construction. To successfully advance digitalization in the construction industry, it is vital to adapt and further develop various digital supplementary tools, e.g., for model-based simulation or the application of VR and AR. In regard to the entire life cycle of buildings, relevant data from the as-built model must be linked to the facility management software environment by digital tools. Considering that existing buildings are not designed with BIM and that there is no digital twin, difficulties emerge in the planning of reconstruction. Due to outdated or missing plans, construction measures are difficult to arrange without collisions and plan changes occurring during construction. In this respect, the elaborated solution-approaches are not always applicable to conversion measures. Further research is needed to determine the economic impact and worth of digitally scanning existing buildings for the operation phase. Thereby, it can be decided whether and in which cases digital methods are useful for renovations and extensions of existing buildings. A comparison of the economic aspects in relation to the effort involved can help to balance the disadvantages and benefits.

**Author Contributions:** Conceptualization, S.H., D.G. and S.K.; methodology, S.H., D.G. and S.K.; validation, S.H., D.G. and K.K.-A.; formal analysis, S.H., D.G. and S.K.; investigation, S.H. and S.K.; resources, D.G. and S.K.; data curation, S.H., D.G. and S.K.; writing—original draft preparation, S.H. and S.K.; writing—review and editing, S.H. and K.K.-A.; visualization, S.K.; supervision, K.K.-A.; project administration, S.H.; funding acquisition, K.K.-A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research paper was written as part of the project KlinikBIM. This project was funded by the German Federal Institute for Research on Building, Urban Affairs and Spatial Development on behalf of the German Federal Ministry of the Interior, for Building and Home Affairs with funds from the Zukunft Bau research promotion.

**Data Availability Statement:** The transcribed interviews are not publicly available due to privacy restrictions.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


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