*1.1. Issue*

Due to the uniqueness of each building, the requirements for the realization of construction projects are highly complex nowadays. Therefore, construction projects require process optimization of the workflows already in the planning phase. This is necessary due to the scope and desired speed of realization of projects, as well as the number of stakeholders involved. Additional pressure on costs and deadlines, as well as unforeseen changes in conditions, increase the need for information and communication in construction projects. Otherwise, the quality of design and execution will be compromised [3] (p. 173).

**Citation:** Hartmann, S.; Gossmann, D.; Kalmuk, S.; Klemt-Albert, K. Optimizing Interfaces of Construction Processes by Digitalization Using the Example of Hospital Construction in Germany. *Buildings* **2023**, *13*, 1421. https:// doi.org/10.3390/buildings13061421

Academic Editors: Simon P. Philbin, Yongjian Ke and Jingxiao Zhang

Received: 20 March 2023 Revised: 20 May 2023 Accepted: 21 May 2023 Published: 30 May 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

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A significant problem in construction projects is further planning during construction. Planning is often overtaken by reality, and coordination between the stakeholders is often difficult to reconcile with the construction process. Coordinating the provision of construction services is an additional and special challenge in large-scale projects [4]. Furthermore, there are supply bottlenecks due to impending resource constraints or logistical difficulties caused by the pandemic. In the following, three worst-case scenarios from projects in Germany are described, which, due to significant design errors, have led to a drastic increase in costs and a considerable delay in project completion.

A large number of design and construction errors were discovered at the new Berlin airport, which opened with a delay of nine years. First, construction work had already been commissioned, although the necessary building licence for the construction had not been issued by the local authorities. Secondly, the planning phase had not been completed before the start of construction, so modifications had to be made during the construction phase. The subsequent changes caused high costs that had not been included in the calculations. Thirdly, the construction was characterized by considerable deficiencies in execution. A particular difficulty was the fire protection, which was affected by the technical problems of the fire alarm systems and incorrect installation of cabling. Some of the construction deficiencies could be traced back to inadequate or even missing construction supervision, which delayed consultations and impeded proper interface coordination [5]. In total, the planning and construction costs increased from an estimated 1.9 billion euros (EUR) to 5.9 billion euros (EUR) in 2020, when the airport was finalized [6].

The Elbphilharmonie, a concert hall in Hanover, built from 2007 to 2016, is another well-known construction project due to its increased costs. At the beginning of planning, the opening was envisaged in 2010, whereby the total costs were estimated at around 186 million euros (EUR) [7]. Due to a multitude of poorly coordinated contracts and interfaces between executing companies, the project duration was delayed by about 6 years and led to construction costs of 789 million euros (EUR) [8].

The project Stuttgart 21, entailing the rearrangement of a railway junction in the city of Stuttgart, represents another example of the effects of inadequate planning and coordination. The scheduled project completion, initially planned for the end of 2019 to thebeginning of 2020, has been postponed several times. Meanwhile, the opening of Stuttgart's main station is scheduled for December 2025, and other parts of the project are scheduled for even later [9]. The costs of the project increased from 2.6 billion euros (EUR) to 9.15 billion euros (EUR) [7]. The extent of the variations in costs of the described projects can be illustrated in Figure 1.

**Figure 1.** Planned and current costs of large-scale projects in Germany in 2017 (own illustration).

In Germany, the analyzed projects are classified in a special category for complex buildings, so-called "Sonderbauten", due to their size and type of use. Compared to residential and administrative buildings, projects in this category must fulfill particularly high requirements, e.g., in the area of fire protection. With increasing complexity of the regulatory and constructional requirements of a project, planning becomes more extensive with an increased risk of potential errors. As part of the critical infrastructure, hospitals in Germany also fall into the category of so-called "Sonderbauten" due to their special structural and regulatory requirements that need to be considered during planning and in further life cycle phases [10]. In addition, there is a multitude of use-specific requirements and stakeholders, such as doctors and the extra trade of medical technology.

The specific challenges in hospital construction can, for example, be presented by the construction project Centre for Operative Medicine 2 (ZOM II) in Düsseldorf. The project shows that hospital projects are prone to planning errors and associated execution deficiencies, mainly due to their high complexity. The ZOM II of the University Hospital Düsseldorf was mainly designed for surgically oriented hospitals. Five different clinics are integrated in ZOM II, including a neurosurgical clinic and an orthopaedic clinic. The clinics have a joint wing for surgeries with ten operating rooms. Furthermore, a central emergency department, a helicopter landing pad on the roof, as well as an intensive and intermediate care ward, are available [11]. For those patients who do not require intensive care, there are 288 beds in modern two-bed rooms [12]. Due to the organisation of these different subject-specific areas, the hospital requires distinct supply and logistics planning for the ongoing operational phase. The building of ZOM II was opened in 2014, with a delay of four years, and the additional costs amounted to about 180 million euros (EUR) [13]. University Hospital Düsseldorf has suffered a great loss due to the delayed commissioning. For example, equipment that had already been purchased could not be used and was already outdated at the time of commissioning. Additional burdens resulted from hiring new staff, which could not yet be employed due to the above-mentioned delays, but they, nevertheless, claimed their wages. The court proceedings, which have involved damages of 63 million euros (EUR), have not been concluded yet [14].

Effects of delays are particularly serious when construction work is carried out on existing buildings during the ongoing operational phase in hospitals. Construction delays can cause immense effects on the ongoing hospital operation and should be prevented to ensure the wellbeing and appropriate care of patients. In this context, the quality of the construction work should not be neglected under any circumstances, as otherwise harmful effects on the patient's health may occur (e.g., impure hospital hygiene). Furthermore, redundant protection of the functionality of vital equipment and devices in hospitals is necessary at all times to maintain supply in the event of technical malfunctions or emergencies.

It should be kept in mind that the medical field is in a constant process of change, which is reflected in even shorter innovation cycles in medical technology. This is accompanied by an increase in the necessary investment costs for the construction and operation of hospitals to be able to guarantee high-quality health care. The constantly changing medical, political, and constructional requirements often lead to hasty decisions. Therefore, hospital operators are unable to meet the demand with sustainable safeguarding. However, every renovation measure in a hospital leads to a strong restriction of the ongoing operation. The aim is to create efficient, sustainable, and goal-oriented planning by involving all necessary stakeholders at an early stage of planning to keep the costs, the effort, and the high complexity in hospital construction manageable. Thus, all relevant requirements should be considered from the very beginning, and interfaces can be defined in advance [15] (p. 3).

Renovation measures, extensions, or refurbishments can usually take place simultaneously with the ongoing operation of a hospital. By taking certain protective measures, hospitals can maintain their day-to-day operations. Therefore, the inconvenience caused

by the construction work, such as noise and soiling, must be curbed and adapted to the operational conditions [16].

#### *1.2. Purpose*

Due to these comprehensive effects, not only in terms of construction, but also in terms of social relevance, there is a huge need for action in the handling of project management in construction, according to Viering et al. in 2007 [17]. In complex buildings, the planning and definition of interfaces in the construction process play a vital role. Interfaces are points of contact between different matters or objects and are also defined in conventional linguistic usage as a connection or transition point between two processes or, in more general terms, between two areas. In construction practice, this consideration cannot be limited to two units, but it must be extended to a chain of units, which occur, among other things, in the form of tasks, activities, and responsibilities of the stakeholders.

Wukonig described, in 2011, how interfaces in construction projects arise not only between the stakeholders, but generally between functionally separated areas and tasks of a project [18] (p. 6f.). The points of contact arise in the subtasks of the different design work, the execution of different trades, as well as monitoring and control tasks. In many cases, this is due to the contractually demarcated areas of liability and responsibility. For coordinating interfaces, a proper and time-critical communication between all stakeholders is indispensable, starting with the definition of uniform terms. Otherwise, technical terms or concepts can be interpreted differently and cause confusion and misunderstandings. The aim of communication is primarily the exchange in information, as well as the identification of information gaps, to link the created subtasks with each other. In order to avoid diverging interpretations, there is a need to control the flow of information in a construction project so that information gaps are kept as narrow as possible. Control is achieved by defining the availability of data for stakeholders to avoid contradictory information and to ensure that the flow of information does not become excessive, as well as that the actual activities are not neglected. Further control elements are available in the form of checklists, tables, or as plans with standardised presentation rules [18] (p. 78f.).

In 2015, Lin developed the ConBIM-Interface Management system to enhance interface information sharing and tracking efficiency. It uses three-dimensional interface maps and the BIM approach to track and manage interfaces in a graphic form [19]. In 2018, Alaloul et al. presented potential benefits, as well as challenges and strategies, for the introduction of smart technologies in the construction process [20]. Whereas, in 2022, Safikhani et al.'s paper highlighted the concrete benefits to the construction process of using VR technology in combination with the digital method Building Information Modeling (BIM) [21]. In 2022, Sun and Liu proposed a novel hybrid model of Digital Twin-Building Information Modeling. The model helps in assisting the dispatch systems in the construction projects to a greater extent than when compared to the implementation of individual technologies [22]. In an article from 2022, Li et al. proposed the novel idea of Hospital Information Modeling, an expansion of BIM for hospital settings [23]. Sepasgozar et al. presented a roadmap for developing and implementing disruptive technologies for the construction industry, in 2023 [24]. Various digital technologies, such as BIM or augmented reality (AR), are presented to optimize processes.

In this article, the process of construction measures is itemised regarding their problems concerning the reduction of the effects of planning and construction faults in the future. These difficulties are identified and analyzed using the example of hospital construction in Germany, as there is a particularly large number of interfaces to be defined due to the special characteristics of the use and requirements arising from critical infrastructure. Based on this, solution approaches are developed to optimize these interfaces and to reduce mistakes in the planning phase. In developing the solutions, digital methods are used to simplify the flow of information and communication and, thus, to intervene at the source of the interface problems. The solution approaches are transferable to other complex buildings with infrastructural, as well as social, significance.

#### **2. Methodology**

The literature research was carried out to obtain information about the status quo regarding interfaces in construction process and possibilities for optimization using digital methods for describing the research gap and the purpose of this article. The issue was dealt with using the example of hospital construction, since, due to the complexity caused by a higher number of trades, stakeholders require more interfaces than in other types of building. Since this work was developed as part of the research project KlinikBIM, whereby a guideline for the implementation of BIM in hospital construction in Germany is being created, the requirements for hospital construction in Germany were taken into account. In order to obtain background information, including the legal framework, as well as the basic requirements of construction measures in hospitals, a review of the literature was carried out.

Based on these findings, an analysis of interfaces in hospital construction processes was conducted through ten guided interviews with experts on the topic, who are from Germany. They are also part of the KlinikBIM project consortium. The interviewed experts are experienced in the field of hospital construction and belong to different subjectspecific areas, such as structural design, architecture, or the construction and operations department of the operator. Thereby, the intention was to identify interfaces in hospital construction, as well as to obtain an opinion on digitization topics and their potential for optimization. The interviews were conducted by video conference with the use of a guideline. Although the questions were specified, the interviewees were still able to answer freely and give examples. The interviewer was also given the opportunity to ask questions in this regard. Mayring's qualitative content analysis was chosen for the evaluation of the guided interviews, which aim to filter out a certain structure from the material to apply it in the form of a category system.

The guided expert interviews and qualitative content evaluation offer the advantage of generating new insights while proceeding in a highly rule-governed and schematic manner. Furthermore, the described methodology enables the establishment new theoretical considerations, based on interview transcripts. Because of the underlying transparency of qualitative content analysis and its applicability to a wide variety of content, it represents an adequate tool for gaining scientific knowledge in the present case.

The evaluation method allows us to assign and to analyze the different interfaces to superordinate problems, such as errors in the planning or in the construction phase. Based on the results from the literature research and the interview evaluation, solution approaches for optimizing the interfaces could be developed. In addition, strategic recommendations for action are given.

#### **3. Legal Background**

In this research report, the legal requirements of the health care system and building law are exemplified by the German regulatory framework. Due to the federal structure of Germany, the building regulations differ in the various German states. Nevertheless, the deviations and the influence on the objective of the present research can be assessed as minor.

In Europe, the primary approach is the sovereign regulation of buildings by the state. There is a superordinate European framework of building regulations, such as EU Directive 305/2011, which regulates the marketing of construction products in the European Economic Area and defines the basic requirements for buildings as a European standard. Due to the principle of subsidiarity prevailing in the EU, the implementation of these requirements is the responsibility of the EU member states themselves. On this basis and the European interest in the exchange in goods and products, most European countries have building regulations and standards that may differ in content, but they serve to avert hazards and to ensure a functioning coexistence [25] (pp. 11 and 16).

In this article, Germany/Lower Saxony's ordinances and laws were used as an example, as this work is connected with the research project KlinikBIM, and the experts of the consortium were from Germany, predominantly from the federal state of Lower Saxony.

Besides new constructions, measures to secure and further develop existing buildings, such as reconstruction and renovation measures, were also considered. This leads to a large number of laws and regulations, which partly need to be taken into account in hospital construction and partly can be regarded as recommendations. However, since there is no clear nationwide model ordinance on the requirements for hospitals, some federal states, such as Baden-Württemberg or Brandenburg, have issued recommendations and ordinances. On the contrary, Lower Saxony follows the model hospital ordinance or works on the basis of the recommendations and ordinances of other federal states because the model hospital ordinance only serves as a guide and is thus formulated with restraint [10].

In addition to the building regulations, there is a particular fee schedule in Germany, which represents the chronological sequence of a planning process by means of service phases [26] (p. 96). In addition, the scope of services for project management is described by the German Committee of the Associations and Chambers of Engineers and Architects for the Fee Schedule (AHO) in the AHO publication series in booklet no. 9 [27]. The descriptions of the AHO and the fee schedule are not statutory requirements, but merely a standard established in the market. Furthermore, there are numerous standards that are relevant to hospital construction, for example, DIN 1946-4 for ventilation and airconditioning systems in the healthcare sector [28], DIN 6812 for medical X-ray systems [29], or DIN EN ISO 7396-1 concerning piping systems for medical compressed gases and vacuums [30].

#### **4. Findings from Interviews to Identify the Key Interfaces in Hospital Construction**

To analyze the existing interface problems in hospital construction, the expert interviews were considered and evaluated separately. Based on the resulting findings, the interface problems can be narrowed down and analyzed. For all interface issues, the later collisions are identified, and their impact is greater. Consequently, the following evaluation is used to develop solution-based approaches that can be used to facilitate construction measures in the future.

### *4.1. Identification of Important Stakeholders in Hospital Construction Measures*

According to the interviewed experts, the hospital is considered the building owner. Often, the hospital has its own construction department, which is responsible for planning and construction measures in the building. It represents the interface between the hospital executive board, the supervisory board, the board of directors, the physicians, and the nursing staff. Furthermore, the interests of the patients and their visitors must be taken into account. Regarding the building law, building supervision authority is the highest priority. Furthermore, municipalities, as well as representatives of public interests, participate in target planning at the state level, and they support the administrative level. They ensure that the interests of the municipality are respected, as well as that development plans are created and adapted, if necessary. Furthermore, other authorities involved, such as the nature conservation authority or the trade control, belong to the administrative level as representatives of public interests. Another representative of public interests is the fire brigade, which must be involved in fire protection measures.

The realization of the building project begins with the commissioning of the planning services. Especially, for new hospital buildings, general planners are commonly commissioned to simplify communication. However, working with architects and various specialist planners is also feasible. Due to the complexity of the planning, a consultant advises the building owner. The large number of specialized planners led to the commissioning of the executing companies, which is usually carried out as an individual contract. To assist the owner, a project manager takes over the coordination of the different stakeholders. Legal consulting can be considered for general advice or for decisive questions. The most

important stakeholders in hospital construction, according to the interviewed experts, are outlined in Figure 2.

**Figure 2.** Stakeholders in clinic constructions (own illustration).
