How to Assess Sustainable Planning Processes of Buildings? A Maturity Assessment Model Approach for Designers

: Over the past decades, it has become apparent that increasing demands in the construction industry have repeatedly led to project delays and increased project costs in practice. These demands have increased as a result of international and national action plans that have been developed to achieve the climate target paths and, therefore, the necessary reduction of CO 2 emissions in the construction industry. We address this problem by developing a sustainable construction maturity model (SCOMM) to answer the following research question: “What is a holistic quality assurance tool for the early design phase of buildings to monitor (sustainable) planning practices in order to achieve better certiﬁcation results?”. The model includes a self-assessment procedure for the building design process, based on Software Process Improvement and Capability dEtermination (SPiCE) and the German Sustainable Building Council (DGNB) building certiﬁcation system. The results show that systemic interactions between sustainability criteria can be identiﬁed in the early design phase, allowing the quality of planning practices to be evaluated and early project management to be implemented to achieve the best certiﬁcation results. Our ﬁndings will enable clients and users of the construction industry to better manage the complexity of the sustainable design process and avoid undesirable developments in building projects.


Introduction
Due to increasing climate change, both clients and users of the construction industry have recognized the growing importance of sustainable construction [1]. This form of construction demands the consideration of the three dimensions of sustainability (environmental, economic, and social) throughout the life cycle stages of a building. Since the last decade of the 20th century, the use of assessment frameworks to evaluate sustainability in buildings has been firmly established [2][3][4], resulting in the development of more than 600 available assessment methods [5]. Actors in the construction industry apply these methods to address a spectrum of sustainability-related topics, which vary widely from a single subject, such as energy efficiency, to a broad range of subjects belonging to any of the three dimensions of sustainability.
At the building level, so-called building certification systems have become entrenched. Building certification is basically carried out to improve the building-user-environment system, requiring various sustainability aspects to be considered. The Green Building Council (GBC) focused on aspects of environmental sustainability to support principles of strong sustainability, while contemporary certification systems direct the focus toward the use of enterprise resource systems, technology and knowledge management or collaboration processes [33]. Regarding MMs, the two most frequently used models are the Capability Maturity Model Integration (CMMI) and the Software Process Improvement and Capability dEtermination (SPiCE).
Further MMs have been developed for the construction industry based on existing MMs for the software industry, mostly Capability Maturity Models (CMM) or CMMI. These MMs mainly refer to project management, as well as individual sub-disciplines of project management, such as risk management and knowledge management. So far, MM have mainly been applied to assess organizational processes in order to evaluate the maturity of an enterprise in relation to a set target. By developing the sustainable construction maturity model (SCOMM), we have developed a model that enables an assessment to be performed at the building level. In this context, it is essential to have a holistic quality assurance self-assessment tool to evaluate the sustainability of planning practices and control their implications. Furthermore, the transparent and comprehensible communication of information and knowledge is an important part of the evaluation of the building performance.
As in the software industry, researchers have developed several process improvement frameworks for the construction industry over the past decade [34]. Table 1 lists some of the MMs identified in the existing literature that have been developed specifically for the construction industry. The current MMs mainly address the assessment of enterprises in terms of project management.  [47] Standardised Process Improvement for Construction Enterprises SPICE [48] Construction Supply Chain Maturity Model CSCMM [49] Maturity Model for Construction Supply Chain Relationships SCM [50] Some MMs have been developed in the construction industry to support a variety of issues related to project management [40,51]. Many of these address knowledge management [52,53] and risk management [54][55][56], while other areas frequently addressed include supply chain management [49,50,57], contractor safety [58], and information management [59]. The applications of most of the assessment methods available for use in the construction industry have demonstrated that the MM can be used to identify inefficiencies and weaknesses and highlight performance improvement measures, helping project managers achieve project objectives more effectively [60].
The results of Wendler's extensive literature review on MMs clearly show that the field of the application of MMs in the construction industry still represents unexplored territory; namely, only ten articles were assigned to the subject area Construction Processes [33]. Other than the MMs models developed in the areas mentioned above, no MM currently exists that can be applied to assess sustainable planning practices. In this context, only the concept of an MM for sustainable construction developed by Goh and Rowlinson needs to be mentioned [61]. However, the construction industry is a highly segmented industry with many actors and disciplines involved, which leads to communication problems due to incomplete and non-transparent planning processes. Therefore, a quality assurance tool is needed-especially in the construction industry-that includes a systemic approach and leads to the reduction of complexity to prevent project deviations from the holistic project goal in the early design phase. Besides quality assurance during the design phase, building owners, planners, and project managers must be presented with a first step to structure and traceably process sustainability requirements from a holistic perspective.
The goal of the research described in this article was to combine the theoretical framework of the maturity assessment method and building certification systems to answer the following research question "What is a holistic quality assurance tool for the early design phase of buildings to monitor (sustainable) planning practices in order to achieve better certification results?". In this study, we took advantage of the Software Process Improvement and Capability dEtermination (SPiCE) model and combined it with the sustainability criteria for the building certification system of the German Sustainable Building Council (DGNB). The proposed hybrid model (i.e., the sustainable construction maturity model, SCOMM) combines the advantages of a classical maturity model and the long-established DGNB certification system to enable self-assessment of (sustainable) planning practices and, thus, the implementation of early project management to achieve the best certification. The application of the developed model was validated based on a first case study. Detailed information on the application can be found in the Supplementary Materials.

Materials and Methods
In addition to ensuring quality and supporting the principles of sustainable construction by carrying out a maturity assessment, we specifically considered the Software Process Improvement and Capability dEtermination (SPiCE) and the German building certification system DGNB. Our specific focus was to adapt the fundamental principles of SPiCE for use in sustainable construction based on the DGNB building certification system.

Software Process Improvement and Capability dEtermination (SPiCE)
The Software Process Improvement and Capability dEtermination (SPiCE) is an international standard applied to conduct maturity assessments of business processes, although it was originally intended for use in software development. It was adopted in 1998 as a technical report in a preliminary version and was replaced by the first version as an international standard in 2006. Currently, it consists of ten parts [23][24][25][26][27][28][29][30][31][32], whereby the first two parts were replaced in 2015 by the standards ISO/IEC 33001 [62] and ISO/IEC 33002 [63].
The core elements of SPiCE are the improvement of processes in organizations and the determination of process capability. The assessment of process capability with an MM based on SPiCE is defined by the so-called capability levels. Capability levels highlight the quality achievement of processes derived from single process purposes and process attributes (PAs). Fulfilling a process comprises the satisfaction of an individual process purpose as well as the implementation of relevant PAs. The assessment takes place at six levels (incomplete, performed, managed, established, predictable, and optimizing), which the user evaluates by examining PAs, whereby the process purpose is assigned to PA 1.1 process performance. All in all, PAs represent the measurable properties of a process quality characteristic. In SPiCE, a total of nine PAs (1.1 to 5.2) are assigned to the capability levels, each of which are described by the base practices and generic practices. The former practices represent activities that contribute to achieving a specific process purpose, while the latter encompass activities that contribute to achieving a specified PA.
To fulfil the PA 1.1, the user only evaluates base practices, but the generic practices must be evaluated to fulfil the remaining PAs 2.1 to 5.2. The PAs are shown in Table 2.
ISO/IEC 33002 defines a rating scale consisting of four values (N-P-L-F scale) that can be used to evaluate practices. This scale is a four-level assessment scale, which ranges from N (not achieved) to P (partially achieved) and on to L (largely achieved) and finally to F (fully achieved). N-P-L-F assessments should be performed for each base and generic practice of a process. By using a specific calculation algorithm, conducting an N-P-L-F assessment results in the fulfilment of PAs and, therefore, the achievement of the capability levels of processes. Subsequently, the processes can be grouped into process areas, and the capability levels can be aggregated to a maturity level. Table 3 shows the bandwidths of the calculation algorithm for the target achievement. Table 3. N-P-L-F calculation algorithm [63].

Degree of Achievement Bandwidth Meaning by Words
N-not achieved 0-15% Evidence of fulfilment of the PA is not available or very scarce.
P-partially achieved >15-50% An attempt was made to meet the PA, and this was partially achieved. However, some points of the process attribute are difficult to verify.
L-largely achieved >50-85% A systematic approach has been used to integrate the points of the PA. Despite some remaining weaknesses, this has been largely achieved.
F-fully achieved >85-100% The PA has been fully implemented within the process. A systematic approach is used to ensure that it is implemented correctly and evidence of this is available. There are no significant weaknesses.
This PA assessment forms the bedrock of the evaluation of the process capability level. To achieve a capability level, all PAs on the previous levels must be evaluated as F (fully achieved). The PAs of the capability level to be achieved must be evaluated as L (largely achieved) or as F (fully achieved).

Building Certification System DGNB
The European evaluation concept that is generally applied to assess the sustainability of buildings-the so-called second-generation certification systems-considers technical and functional qualities, as well as the classic three pillars of sustainability (environmental, economic, and social). The German building certification system DGNB of the German Sustainable Building Council is one of these systems.
The DGNB has developed its own certification system to make sustainable construction practically applicable, measurable, and comparable. First launched in 2009, construction industry actors have steadily improved the system. Today, it is not only the most advanced certification system worldwide, but it is also recognized internationally as a Global Benchmark for Sustainability. The certification system exists in several schemes for buildings, districts, and interiors. Within this system, a distinction is made between the categories of office, education, residential, hotel, and consumer markets. To develop the SCOMM, we used the DGNB system for "New Construction-Office", as different building typologies have different criteria weightings. The structure of this scheme, including the criteria weighting, is shown in Table 4. The DGNB was not developed to distribute certifications to gain market advantages, but to promote and ensure holistic building quality with reference to established certification criteria. However, to obtain certification, certain minimum requirements must also be met, which are known as knock-out criteria (K.O. criteria). These include indoor air quality (SOC1.2), design for all (SOC2.1), and fire safety (TEC1.1). Such criteria can vary depending on the scheme and are specified in the individual schemes.

Development of a Sustainable Construction Maturity Model (SCOMM)
Most MMs consist of a rating system that can be applied to evaluate the degree of maturity. However, the structure of MMs can differ from model to model. Proença

Name of the Maturity Model
Since the developed MM includes the assessment of sustainable planning processes and, thus, the early assessment of the overall building quality, the model was named the sustainable construction maturity model (SCOMM). Figure 1 shows how the SPiCE nomenclature was transferred to the nomenclature in SCOMM using the DGNB building certification system. The example of the process thermal comfort illustrates this transfer. Once the relevant planning practices to satisfy individual stakeholder preferences have been identified, SCOMM can be used to perform quality management of planning in the design phase.

Number of Maturity Levels
The SCOMM is based on SPiCE and involves the capability dimension approach. This approach provides a framework for the measurement, including six capability levels and the associated nine PAs. To determine a capability level, the underlying planning practices (base practices and generic practices) in the respective processes are evaluated and summed up using the N-P-L-F evaluation algorithm described in the section entitled Software Process Improvement and Capability dEtermination (SPiCE).
Once the assessment is complete, the user can check the quality of the individual planning practices. In addition, the user can obtain maturity levels for individual process areas after aggregating the process evaluation. Similarly, the user can merge process areas and check the maturity level for the overall quality of a building. The SCOMM includes six capability levels for the evaluation of planning practices and five maturity levels for the measurement of the maturity of the process areas and the overall building quality.

Classification and Number of Process Areas
To apply MMs, the user must define the goals that are to be achieved. These include the desired maturity level and the definition of the areas to be evaluated [18]. Some MMs assign processes to higher-level process areas, which should facilitate the evaluation to the desired extent. This means that only those process areas that are relevant for achieving a desired objective need to be included in the evaluation.
Based on the DGNB building certification system, we defined six process areas. These six process areas are defined by the six quality sections of DGNB (environmental quality, economic quality, sociocultural and functional quality, technical quality, process quality, and site quality).

Maturity Level and Capability Level Definitions
To evaluate planning practices, the N-P-L-F evaluation algorithm based on SPiCE is used. After evaluating the planning practices, the user can calculate the capability levels for the superordinate process areas. In the SCOMM, the user applies six capability levels as proposed by SPiCE. Table 5 shows the numbered levels and the corresponding capability level. Extensive definitions of the individual capability levels are given in the Appendix A. Table 5. Overview of capability levels.

Numbered Level Capability Level
Level 0 Incomplete process/planning practice Level 1 Performed process/planning practice Level 2 Managed process/planning practice Level 3 Established process/planning practice Level 4 Predictable process/planning practice Level 5 Optimizing process/planning practice Level 0 Incomplete process/planning practice Level 1 Performed process/planning practice Level 2 Managed process/planning practice After the achieved capability levels are merged, a maturity level can be reached (e.g., for the six DGNB quality sections or the overall building quality). The five maturity levels are shown in Table 6. Extensive definitions of the meanings of the individual maturity levels are given in the Appendix B. The SCOMM has been specifically developed for the quality management of planning practices related to the implementation of sustainable construction in an early building design phase. The systemic interactions of the processes (i.e., of the DGNB certification criteria) are included in the SCOMM. Moreover, especially the systemic interdependencies among the planning practices are highlighted and explained. The domain of the MM, thus, covers the systemic consideration of planning practices in the early building design phase to improve the DGNB certification results.

Description of the Assessment Method
As proposed in ISO 33001, SCOMM involves the N-P-L-F assessment. These N-P-L-F assessments should be performed for each planning practice (base practice and generic practice). Using a specific calculation algorithm, the N-P-L-F assessments result in the capability levels of the superordinate processes. By aggregating the processes to process areas, the user can obtain the maturity level for six DGNB quality sections and the design quality for the whole building.
The user only evaluates base practices (BP) to achieve the PA 1.1 process performance. BP are activities which-when consistently performed-contribute to achieving a specific process purpose. In the SCOMM, these include the planning practices designed by the planners. Exemplary BPs are listed in the Appendix C.
To achieve the remaining PAs, we defined generic practices (GP). GP are activities which-again when consistently performed-contribute to achieving a specific PA. All GP developed for the SCOMM can be found in the Appendix D. Figure 2 provides a schematic view of the assessment method. The SCOMM structure follows a hierarchical structure derived from the DGNB building certification system and SPiCE. Accordingly, the lowest level of the hierarchy represents the building quality or the certification result, respectively. This building quality is further divided into the six process areas corresponding to the six DGNB quality sections; the areas also contain their weighting based on the DGNB scheme "New Construction-Office". The next level displays the individual processes, which correspond to the 37 DGNB certification criteria. The last level of the SCOMM illustrates the subdivision of the processes into the BPs and GPs. These practices are finally assessed using the N-P-L-F assessment scale, resulting in capability levels for processes or in the case of aggregation for process areas.

Application of SCOMM
Although planning buildings based on recurring procedures and processes may not always be ideal, because many buildings are unique, the SCOMM developed in this work provides an effective quality-assurance tool that guides the user through the planning process based on a flowchart defined in the early building design phase. Figure 3 shows the flowchart that illustrates the SCOMM workflow. First, the user selects the processes (e.g., thermal comfort, visual comfort, sound insulation) and determines their desired quality level. Using the SCOMM, the user can identify relevant planning practices (base practices and generic practices) for all processes. If the planner identifies a potential for optimization within the relevant planning practices, the user can examine this potential in more detail in the following steps of the developed MM. After selecting a planning practice, two further questions arise: (1) Whether the planning practice is a knock-out (K.O.) practice (i.e., whether this planning practice addresses a knock-out criterion as defined by the DGNB building certification system) and (2) whether the planning practice has a systemic influence on other processes. K.O. criteria, as defined by the DGNB building certification system, can prevent successful certification in any case, but K.O. practices also can be essential conditions that are defined by the stakeholders or planners themselves and must be implemented.
While SCOMM can be efficiently used to identify relevant planning practices, it can also be used to highlight the systemic relevance of a planning practice. If the user answers the two questions described in the previous paragraph with "no", the planning practice is identified as not systemically relevant; therefore, the user learns that it has no systemic relevance with respect to the overall planning quality of the building.
However, if the planning practice is a K.O. practice or is identified as systemically relevant, this practice will be evaluated with the N-P-L-F assessment algorithm. Once this evaluation has been carried out, the result is compared with the previously defined quality level. The user must decide whether this level has been achieved. If the defined quality level has not been fully achieved (evaluated as "not achieved", "partially achieved", or "largely achieved"), planners can consider whether they can adapt the design so that the planning practice is evaluated as "fully achieved". If the planners can create such an alternative design, the user checks the newly developed planning practice again for its systemic relevance. This receives an evaluation result of "fully achieved" if-and only if-the defined quality level has been fully achieved.
Once the user has applied SCOMM to assess all the planning practices for the various processes, they need to take the next step and assess the generic practices. After all processes have been assessed, the user applies the calculation algorithm to determine the capability levels of each process and the maturity level of the six DGNB quality sections or the overall building design quality. After applying the SCOMM, the results can be presented in the form of a sustainability report, which can serve as a planning manual for the early design phase of sustainable construction. Figure 4 shows an extract of the SCOMM which concerns the capability assessment of a selected process "thermal comfort". SCOMM automatically displays all possible synergies and trade-offs based on the deposited interactions for the selected planning practice "reduce energy demand". The SCOMM mainly contrasts with current systemic approaches (e.g., Vester's paper computer model, which places a focus on the identification of systemic effects of overarching subjects [67]) in that it can be used to visualize the systemic effects of individual subjects (here, planning practices). Thus, the systemic interactions among individual planning practices and indicators of the DGNB's sustainability criteria become visible. This ability to visualize and evaluate planning practices provides users with a holistic view of the entire planning process, supporting quality-assured planning.

Exemplary Output of the SCOMM
On the left-hand side of Figure 4, the base practice (i.e., the selected planning practice) within the selected process area is shown. The exemplary output shows the process "thermal comfort", which is to be assigned to the sustainability quality "socio-cultural and functional quality" of the DGNB building certification system. One possible planning practice to improve thermal comfort is described by the reduction in energy demand, which can be achieved if different specific measures are applied. If, for example, solar radiation is reduced by means of shading to reduce the energy demand, this measure also has positive effects on the indicator "sun protection", which should be assigned to the process area "visual comfort". On the other hand, the installation of shading systems can also have a limitation (i.e., a trade-off) with respect to the indicator "daylight factor", which is also assigned to the process area "visual comfort". Another measure that can be applied to reduce the energy demand is to optimize the U-value of the building envelope. This could be achieved by, for example, increasing the material thicknesses or providing additional thermal insulation. These measures have a positive influence (i.e., synergies) on the indicator "heat transfer", which should be assigned to the process area "quality of the building envelope". In addition, the application of these measures can subsequently lead to an increase in the storage mass and an improvement in the indicator "surface temperatures", which is assigned to the process area "thermal comfort". In terms of reducing the energy demand by applying efficiency measures, more efficient technical building equipment could be planned, which, in turn, would have positive impacts on the indicators "passive systems" and "adaptability of the distribution system to suit operating temperatures to enable the use of renewable energy services", which are to be assigned to the process area "use and integration of building technology". Another measure to reduce the energy demand, and that can be derived from the sufficiency strategy, would be to reduce the indoor air temperature. However, this reduction could lead to a trade-off with the indicators "temperatures during the heating period" and "temperatures outside of the heating period (cooling)", which should be assigned to the process area "user control". From an economic perspective, some measures also have both positive and negative effects. While reducing the energy demand lowers the operating costs, which has a positive effect on the indicators "life cycle cost calculations in the planning process", "life cycle cost optimization" and "building-related life cycle costs", which belong to the process area "life cycle cost", the measures described above can also increase construction costs, which has a negative effect on the indicators mentioned. These exemplary descriptions of the interactions clearly show the complexity underlying sustainable construction management.
As shown in Figure 4, the user has rated the planning practice "reduce energy demand" as largely achieved (L). This means that the user largely rates the quality of his planning measure positively, even after considering all interactions with other process areas. The likelihood that this planning practice will jeopardize other project objectives, therefore, is considered low.
The evaluation of all base practices in the respective process areas (i.e., several planning practices can also occur within the same process area) then results in the implementation probability of PA 1.1. After the N-P-L-F assessments of all base practices have been carried out, the user takes the next step and evaluates the generic practices for the selected processes.
The N-P-L-F assessment of the base and generic practices results in a degree of implementation for all PAs associated with a process. The additive combination of the implementation degrees for each PA, which are based on the assessment method, provides the capability levels for each process. Similarly, the capability levels of the processes can be aggregated to the maturity levels for the six DGNB quality section or for the overall design quality of the building.

Discussion
Maturity models are already in use in the construction industry; however, they are primarily applied in a broader sense to project management and in a narrower sense to risk management and knowledge management. The quality management of sustainable construction-supported by existing maturity level models-can currently only be achieved by improving the management processes [61].
Actors in the construction industry have been searching in vain for a maturity model that could be used to assess the quality of planning practices or processes and, thus, the quality of planning for sustainable construction. Our work resulted in the development of just this type of maturity model for sustainable construction (SCOMM), which enables the users (i.e., the individual planners) to monitor their design and increase the quality of planning without investing valuable additional time.
As general advantages of using maturity models, the user can identify the strengths and weaknesses of individual processes; therefore, they are given the opportunity to improve these directly and strategically [8,10]. In turn, this enables companies to achieve higher standards in various areas [21]. By providing the opportunity to improve and develop processes, maturity models reduce the number of (inevitable) errors in the company/planning office and avoid unnecessary additional costs and delays [68]. Another advantage of using these models is that processes can be analyzed before they are executed, rather than simply being improved after a potentially costly error has occurred [13].
If a company/planning office exhibits a high level of maturity, which is also communicated externally, the office can enjoy further advantages on the market, as the level of maturity differentiates it from its competitors. A weakness of maturity models is that introducing maturity models requires the investment of too many resources and that the benefits of their use are not always clear [20]. The introduction of a maturity assessment often fails because the employees display a resistance to the conversion of tried-and-tested processes for the purpose of process optimization due to their lack of understanding [69]. In such situations, management needs to inform employees about the purpose and benefits of such assessments, so that everyone can work together to improve processes [70]. Furthermore, the time required for maturity assessment can be reduced by integrating SCOMM into methods such as Building Information Modeling (BIM) [71].
Assessing the maturity level of a company/planning office can also be problematic, as this is often done by self-assessment due to the additional effort involved. This means that some entrepreneurs may try to position themselves advantageously in the comparison by falsifying the assessment. This problem could be remedied by contracting an external evaluation, but this would involve additional costs [22]. These advantages and disadvantages apply analogously to the maturity model developed for sustainable construction.
Regardless of whether the planning is carried out by a single planner or by several planners in a larger planning office, the planners must be convinced of the usefulness of the maturity model. They also need to be made aware of the fact that a certain amount of additional time will be required for planning due to the execution of the maturity assessment and to accept this fact. When carrying out such discussions, management should clearly emphasize the advantages of using the maturity model. Evaluating individual planning practices engenders a certain degree of self-control in a positive sense. Planned practices are repeatedly scrutinized and specifically checked for their degree of goal achievement. In addition, the synergies and trade-offs related to individual planning practices within the maturity model become apparent. By identifying the synergies and trade-offs, a clearer picture of the systemic understanding emerges, and unexpected short, medium, and long-term effects can be avoided [8,72,73]. By determining the capability levels of individual processes, the user can recommend the application of the necessary control measures already in the early building design phase.
By reducing their planning errors, planning offices can gain a better reputation as compared with their competitors. In this way, the application of the maturity model can also result in an increase in the number of planning contracts. To achieve this purpose, actors in the construction industry should consider including the application of a maturity assessment when tendering and awarding in the future. This compensates for the resulting additional expenditure during the design phase. As one way to receive compensation, the maturity assessment could be included in the schedule of services and fees for architects and engineers (HOAI).
In addition, clients should be made aware of the added value of maturity assessments; the planner should clearly indicate how the assessment helps to avoid planning errors and unexpected additional costs. These unexpected additional costs are significantly higher than the additional planning costs in most cases.
Finally, it should be noted that an extension of the system boundary from the building level to the district or urban planning level is feasible. In this context, the DGNB certification system already offers a certification system for the planning and certification of sustainable districts. Thus, the proposed methodological approach could also be applied to urban planning, unless the underlying sustainability criteria are adapted, the interactions of urban planning practices are identified, and the generic practices for the assessment of the process attributes are adjusted.

Conclusions
The design of sustainable buildings is crucial to meet our climate goals. From a current perspective, it appears as though Austria can only meet its international climate commitments and align with European strategies by investing a substantial amount of effort (i.e., by applying much more ambitious, specific, and resilient measures). The steadily increasing complexity of planning and construction processes calls upon those individuals involved to take what is essentially a new approach to creating (more) sustainable construction. We recognized that a further step was urgently needed to ensure the development of a resilient built environment. We addressed this problem by combining the theoretical framework of the maturity assessment method and building certification systems to provide a holistic quality assurance tool for the early design phase of buildings to monitor (sustainable) planning practices in order to achieve better certification results. This resulted in the development of a new maturity model (SCOMM) that enables integrated sustainability assessment in the early design phase of buildings by providing a self-assessment tool for (sustainable) planning practices and, thus, the implementation of early project management to achieve best certification. The main points of the developed model can be summarized as follows:

•
Combination of Software Process Improvement and Capability dEtermination (SPiCE) model and the building certification system of the German Sustainable Building Council (DGNB).

•
The proposed process-based approach ensures a holistic consideration of all required planning practices by a systematic assessment process. • Assessment of planning practices (i.e., base practices (BP)) and identification of their synergies and trade-offs by applying the proposed maturity model. This new maturity assessment method was developed to enable quality management throughout the early building design phase to ensure a holistic perspective. However, this holistic view can only be achieved if the function of the individual process steps is guaranteed. If individual process steps fail or if interactions are overlooked, the entire sustainable construction management and the entire sustainability certification are at risk.
The stakeholders and planners involved in this project have taken the first step towards structuring sustainability requirements, processing them comprehensibly and carrying out monitoring. When used in combination with the principles of building certification systems, this newly developed model can serve as an important tool that enables users to achieve better building certification results and, thus, better sustainable construction.
In summary, the advantages of the SCOMM can be described in five principal areas: (1) it increases the user's knowledge of the essential planning practices (K.O. practices and systemic relevant practices); (2) it increases the user's knowledge and ability to visualize the interactions that occur among planning practices and processes; (3) it increases the user's knowledge of the maturity level achieved as compared to the planned process maturity and, thus, the implementation of quality management from a holistic perspective; (4) it offers the user the possibility of preparing a sustainability report as a basis for a planning manual; and (5) by combining all of these advantages and by taking into account the maturity model's workflow, the user has a higher chance of achieving a higher certification result.
People who choose to implement SCOMM can visualize the possible effects of decisions in the early building design phase by carrying out three simple steps: define the target, analyze the system, and assess the maturity. Our intention in developing SCOMM was to raise awareness among the involved stakeholders and planners for the potential inherent in this new mode, as well as for various influencing factors in the context of holistic building optimization. The fact that the user can apply SCOMM to visualize interactions and gain knowledge about critical processes or planning practices are decisive factors that help them achieve sustainability goals. The resulting synergies can be consciously considered in further planning process steps, as the possible trade-offs due to diverging target preferences become evident.  Table A1. Capability levels.

Capability Level Definition Process Attribute
Level 0: Incomplete process/ planning practice The process does not achieve its purpose or is not implemented. Little evidence is available. Level 0 is the only process to which no process attributes are assigned.

Level 1:
Performed process/ planning practice The process is implemented and fulfils its process purpose. Input and output work products are in place and ensure that the process purpose is achieved.

PA 1.1: Process performance
This attribute is a measure of the degree to which the process purpose is achieved. Indicators are work products and measures that convert input work products into output work products.

Level 2:
Managed process/ planning practice The process is planned, monitored and adjusted if necessary. The main differences to level 1 are the management of the execution and the work products. The result of the processes is measured by target-performance comparisons.

PA 2.1: Execution management
This attribute describes to what extent the execution of a process is planned and controlled. The application of basic management techniques is affected. PA 2.2: Work product management This attribute describes how well work products are planned and controlled in the process. It is used to check the effort put into identifying, documenting, and managing work products.

Level 3:
Established process/ planning practice The applied and controlled process is now also defined to achieve the desired process result. The established process is a standard process that is defined and adapted.

PA 3.1: Process definition
This attribute indicates how far a process is described. A process becomes a defined process, if a certain degree of customization under consideration from the outside. With regard to the desired process result a process description created.

PA 3.2: Process deployment
The degree to which a defined process is used as a standard process is determined by of the attribute process usage is described. Aspects that are described in the attribute are described, which contribute to the effectiveness of the implementation.

Level 4:
Predictable process/ planning practice The process runs as a standardized process to achieve the desired process results. The process is consistently implemented within defined limits. Deviations are recorded together with their causes.

PA 4.1: Process management
This attribute reflects how well measurement results are used in the assurance process to perform processes. The measurement results are used to determine the degree to which business objectives are achieved.

PA 4.2: Process control
This attribute reflects how far a process is controlled. It can be used to predict whether a process is running within predefined limits. The purpose of control is to detect deviations and determine the causes of these deviations.

Level 5:
Optimizing process/ planning practice The existing process is continuously optimized to achieve current and future business objectives. The execution of processes is continuously improved by introducing new ideas and techniques and changing inefficient practices.

PA 5.1: Process innovation
This attribute describes the degree to which process changes are implemented based on measurements, deviations, new innovations, and new ideas. Recognizing and understanding the causes of change is an important factor.

PA 5.2: Process optimization
The extent to which changes are made to the definition, control, and execution of processes is reflected by this attribute. The effects of changes are estimated in order to achieve the best possible improvement. Optimization must be planned carefully to minimize disruption. Table A2. Maturity levels.

Level 1: Performed
The process purpose is met, based on training, experience, or work procedures following generally accepted guidelines. Company-wide process management does not exist, performance depends largely on personnel and differs from project to project. The results of the process execution are available, but the process execution relies only on the know-how of the project team members. Guidelines, if used, could be building certification systems, for example. However, their application is not consistent throughout the organization and planning measures, management measures, and repeatability measures are generally not implemented.

Level 2: Managed
The process execution is planned and guided. Resources, responsibilities, and instruments are planned according to realistic experiences. The project goals are defined, and the work is monitored, managed, and checked. The guidelines to be applied at project level are known and are applied. Additionally, the work is planned and executed at the individual project levels. Management of requirements and quality assurance are in place. Moreover, sub-processes (e.g., monitoring of milestones, costs, and project progress) are specified and implemented. Project-specific guidelines are planned.

Level 3: Established
Where appropriate, the standard processes are standardized throughout the company. Additionally, their execution is standardized using application guidelines and/or by adapting processes. This provides the foundation for standardized project management, project control, and project planning. The process is person-independent and institutionalized. There is a model for the standard procedure (process model), which has been documented and standardized on an organizational level. Simulations (e.g., LCC or thermal simulations) are performed.

Level 4: Predictable
The performance indicators derived from the measurements and analyses and their ongoing monitoring are capable of systematically identifying any weaknesses. This results in an improved forecasting accuracy. The qualities are quantitatively known, and the risk management is well-established. The process has been quantitatively understood and is being monitored at project level. Productivity and quality are measured, and the relevant parameters are identifiable. Effort estimations are performed methodically, and a PLAN-ACTUAL analysis is conducted. Possibilities for analysis and management can be specified.

Level 5: Optimizing
The information and knowledge gained from level 4 is then used to launch an optimization process. New methodologies and workflows are developed, simulated, and implemented as a prototype. If they are successful, they will be institutionalized. A systematic collection and re-use of empirical values and an error analysis is carried out. Opportunities for optimization resulting from new concepts and new technologies are explored. Long-term optimization goals and visions can be specified.  Requirements for the (construction) project infrastructure (e.g., project references, personnel know-how, experience with the application of methods and tools for sustainable construction, site conditions with regard to the use of renewable resources) for the implementation of a sustainable planning and construction process are identified and documented GP 3.2.3 Resources for implementing the sustainability processes are provided, allocated, and used (e.g., use of sustainability-qualified personnel) GP 3.2. 4 An appropriate (construction) project infrastructure (e.g., tools, documentation) exists on site (in the planning office, on the construction site) for the process  The potential for improvement is analyzed. Systemic SWOT analysis of the process improvement has been performed and sources of actual and potential problems have been identified The benefits obtained are quantified. Quantitative evaluation of the improvements of the changed process in relation to the pre-defined objectives