Introduction
Defining the workflow for creating an optimized 5D BIM model is still a big challenge in the construction sector. The main reason for this is the weak coordination of project departments and poor standardization of all business processes, which makes the application of the 5D BIM workflow difficult.
In this report, the case study of a business - residential building Bužanova - Štrigina is used as an example to provide guidelines for the optimal workflow when creating a 5D BIM model.
Figure 1 Case study showcase
Project Background and Objectives
The Bužanova-Štrigina project is a residential and commercial development in Zagreb, Croatia, undertaken by investor MADO Group. The building comprises 69 apartments and 2 commercial spaces across 7 above-ground floors (with a total area of ~2657 m²), plus two underground levels mainly for parking (128 parking spaces, ~9520 m²). In terms of structure, the building includes two underground floors, a ground floor, five standard floors, and a recessed top floor, arranged in a semi-split-level configuration.
Figure 2 Project render
Figure 3 Project site
The objective of Mastery of Digital’s engagement was to evaluate the existing project documentation – the 3D BIM models, the Microsoft Project schedule, and the detailed bill of quantities – and attempt to integrate them into a unified 5D BIM environment.
This integration aimed to reveal any discrepancies or inefficiencies in the current project data and to establish guidelines for an optimal 5D BIM workflow for future projects. By using BEXEL Manager software to integrate the components, our team could simulate a 5D BIM process and identify what adjustments were needed for success.
3D BIM Model Analysis
The project’s BIM model consisted of two separate discipline models provided by the client’s design team. The primary architectural model included the building’s foundation and structural frame, facade elements, internal partition walls, as well as fixtures like furniture and carpentry. A secondary mechanical model contained the HVAC and plumbing installations.
Figure 4 3D BIM model
The architectural BIM model was organized by defined floor levels (basement levels, ground floor, typical floors, roof, etc.), and included numerous 3D views, sections, schedules (quantity tables), and drawings. The measurement units for quantities were properly defined at project setup, an important practice to ensure consistency in quantity take-offs (QTO)file. A custom material catalog had also been imported so that each element could be tagged with specific material properties. Load-bearing elements in the model included the foundation slab (with strip footings), walls, beams, stairs, and slabs, while non-load-bearing components encompassed facade assemblies, partition walls, suspended ceilings, finishes, carpentry, and furniture. This level of detail provided a solid geometric and material basis for BIM.
Despite the model’s detail, our analysis revealed several gaps affecting 5D integration. Notably, aside from basic geometry and material attributes, many model elements lacked additional information or classification that would later be needed for cost and schedule linkage. For instance, structural elements were not tagged by construction phase or linked to specific cost item codes – they had geometry and material but no metadata tying them to the Bill of Quantities or schedule tasks. Furthermore, while the model was divided into floors in Revit, certain elements spanned multiple levels (e.g. some walls or shafts) without being split or identified per floor (Fig 5, Fig 6).
Figure 5 Walls spanning multiple floors
Figure 6 Incorrectly defined facade construction
This absence of floor-by-floor element segregation is critical: as the case study notes, without floor-level separation of elements, accurate 5D linking is impossible because one cannot reliably tie a multi-floor element to a single location-specific cost or activity. These shortcomings meant that the 3D model, in its provided state, was not fully “5D-ready” – additional information structure would be needed to use it as the central integrating component of a 5D BIM model.
Time Plan Analysis
The construction time plan for Bužanova-Štrigina was created in Microsoft Project and covered only the construction phase (starting with demolition of existing structures and ending with final installations). The planned project duration was 543 days, from an April 21, 2020 start to a March 3, 2022.
Figure 7 Project gantt chart
The schedule was organized using a Work Breakdown Structure (WBS) that attempted to categorize the work. According to the project documentation, a single top-level WBS was created for the entire project covering all trades. For example, under concrete works the WBS was broken down into three sublevels: distinguishing underground vs. above-ground structure, then by floor, then by structural element type. However, this level of detail was the exception rather than the rule – overall the WBS development was described as “quite shallow”, with most work categories only broken down to the first level. In practice, many activities in the schedule were broad and not further decomposed into sub-tasks.
The lack of alignment and detail in the time plan is a clear inefficiency: it prevents precise 4D simulations and makes it impossible to directly map schedule activities to BIM components without additional intermediate mapping (like creating selection sets or splitting tasks). Our team’s findings suggested that to enable 5D BIM, the project’s schedule would require a more detailed WBS (especially for structural works by floor and type) and consistent labeling (possibly incorporating the same codes used in the BoQ or model) so that each activity has a one-to-one or one-to-few relationship with model elements and cost items.
Bill of Quantities Analysis
The bill of quantities (BoQ) for the project was a comprehensive document detailing all works and materials, divided into three major sections by trade categories (1) Construction works, (2) Plumbing and installations (including electrical, mechanical, and sprinkler systems), and (3) Finishes/Craft works. Within these sections, further subdivision existed. For example, Plumbing/installation works were broken down into plumbing & drainage, electrical installations, mechanical installations, sprinkler installations, and sanitary equipment. This hierarchical breakdown is typical for a BoQ, organizing items by trade and work type. Within each subcategory, the BoQ listed numerous cost items with descriptions and unit rates. The case study noted that the concrete and reinforced concrete works items included very detailed descriptions – specifying technical requirements and execution methods for each item. This indicates a thorough BoQ in terms of technical content.
However, a critical observation was made regarding how these cost items were structured relative to the building elements: the BoQ did not separate items by building part or floor. For instance, a single cost item for “Concrete works” might encompass pouring of all internal RC walls and columns on the ground floor together, rather than having distinct cost entries per element or per floor. Similarly, the “Reinforcement works” were divided by types of rebar (e.g. B500B steel, mesh overlaps, penetration reinforcement) but not by which element or level they pertain to. In other words, the BoQ grouped costs by material or work type in a general way, without tagging them to specific locations in the building.
This structuring poses a major challenge for 5D BIM integration. Our analysis showed that there was a mismatch between the cost breakdown structure (CBS) and the project’s WBS. In practical terms, the way costs were aggregated in the BoQ did not align with how tasks were scheduled or how elements existed in the 3D model. The case study concluded that this misalignment – especially the failure to break down costs by element and floor – “prevents [the BoQ’s] integration with the time plan and the 3D BIM model”. A concrete example highlighted in the analysis was: one cost item for concrete encompassed both walls and columns on a floor, while the schedule had an activity only for walls on that floor, and the BIM model did not differentiate walls vs. columns clearly by floor without additional filters. Likewise, reinforcement costs lumped together all rebar types for multiple elements, whereas the schedule or model would treat each element separately. This lack of one-to-one correspondence meant that if one attempted to directly link the 3D model, schedule, and BoQ, the result would be mismatched and inaccurate.
Key Integration Challenges Identified
Analyzing the above components together, Mastery of Digital found that the 3D model, schedule, and BoQ were developed in isolation and were largely inconsistent with each other. This siloed approach is the root cause of the integration difficulties. The case study explicitly notes that these project components appeared to have been created not for a collaborative BIM workflow, but rather as separate deliverables. When attempting to combine them in a 5D BIM environment, numerous integration errors and inefficiencies emerged:
- Misaligned Breakdown Structures: There was a fundamental mismatch between the WBS (schedule structure) and CBS (cost structure). Work tasks were not broken down in the same way that cost items were, and neither matched the breakdown of the 3D model by building elements. For example, an activity covering “all walls on Ground Floor” could not cleanly link to a cost item that combined walls and columns, nor to BIM elements that weren’t distinctly categorized by story. Such misalignment meant any direct linking would be error-prone or impossible.
- Lack of Element-Level Identification: The BIM model did not carry the necessary identifiers to filter or match elements to specific schedule or BoQ line items. Key metadata like phase, floor, or type codes were missing on many elements. This lack of information prevented the creation of precise selection sets (queries) for linking model elements to corresponding activities or costs. The integration attempt showed that without additional filtering info, one could not isolate, say, “Ground Floor RC walls” in the model to link them to a “Ground Floor RC walls” task or cost entry – because the model simply labeled them as generic walls with no floor tag. This is why the case study stresses adding information to each element; the more attribute data in the model, the easier it becomes to filter and accurately link elements to cost items.
- Insufficient Task Granularity and Coding: Many schedule activities were too broad (spanning multiple element types or floors) or lacked a coding scheme. Because tasks were not subdivided by location or specific scope, it was unclear how to attach individual model components to them without fractioning the quantities manually. Moreover, without standardized naming (like including a code that might match a cost item ID or a BIM category), there was no straightforward way to line up tasks with cost items. This required the creation of intermediate mapping (e.g., grouping model elements into custom sets corresponding to each task) which is time-consuming. It was noted that using classification codes in activity names would greatly aid in automation – their absence was a missed opportunity and a source of inefficiency.
- Aggregated Cost Items: The BoQ’s cost items aggregated work in ways that did not correspond to how construction is executed or scheduled. A prime example is the reinforcement work: the BoQ grouped reinforcement by type of steel across the project, but in reality, reinforcement installation is planned per element (each wall, slab, etc., on each floor). Thus, there was no direct link between a “Rebar B500B” cost entry and a specific BIM element or schedule task – that cost entry pertained to many elements in many locations. This aggregation forced any 5D integration to rely on manual take-off calculations and splitting of costs if it were to be accurate. As the report states, without reorganization of cost items by element and floor, linking them to the model was unmanageable.
- Different Data Sources and Formats: The three components were prepared with different software (Revit for BIM, MS Project for schedule, Excel/CSV for BoQ) and by different teams. There was no common data environment or linking key between them. In a well-planned 5D BIM approach, one would establish from the start a common coding system or at least maintain consistency (for instance, using the same naming for building parts in the schedule and BoQ as in the model). Here, that was not done, so the integration had to start by retrofitting compatibility, which is inherently inefficient.
Efforts were made to import all available data into BEXEL Manager and prepare the existing model by creating selection sets and attempting integration. However, due to the previously outlined inconsistencies—such as the lack of a common data environment, missing coding standards, and fragmented documentation—significant challenges were encountered during the linking process. These difficulties, illustrated in the figures below (Fig 8, Fig 9, Fig 10, Fig 11), demonstrate the inefficiencies caused by the absence of structured, interoperable project data.
Figure 8 Creating selection set for RC ground floor walls
Figure 9 Incorrect element filtering
Figure 10 Scheduling conflicts when importing time plan
Figure 11 Linked cost items with BIM elements in Bexel Manager
In essence, the entire project needed restructuring to enable 5D BIM. The integration challenges above resulted in a situation where attempting a 5D simulation with the given data would produce incorrect results or require extensive rework.
Guidelines for Optimal 5D BIM Integration
Based on the identified gaps, Mastery of Digital, formulated a set of concrete guidelines to achieve a successful 5D BIM integration for this project (and similar projects in the future). These guidelines aim to align the 3D model, schedule, and cost data so that they can be linked in a cohesive manner. Applying these best practices transforms the different project inputs into a synchronized 5D BIM model, enabling automated or semi-automated integration rather than unreliable manual matching. The key recommendations are as follows:
- Coordinated & Enriched 3D BIM Model: Ensure the BIM model is fully prepared for integration. This involves floor-level separation of all major elements and the inclusion of comprehensive information attributes for each element. Every physical component (wall, column, slab, etc.) should either be split by story in the model or at least carry a clear parameter indicating its floor level, zone, and category. Additionally, use a single, unified model environment for all disciplines whenever possible (or well-managed linked models) to maintain consistency. A centralized model that all teams contribute to will prevent misalignments and reduce duplicate work. Regular clash detection iterations during design are advised to catch coordination issues early. By project completion, the 3D model should be a reliable, conflict-free representation of the building, where each element is uniquely identifiable by location and type. This solid foundation is critical – it serves as the common component through which schedule and cost data will connect.
- Detailed and Structured Time Plan: Develop a more robust construction schedule with a deeper WBS breakdown and clear activity naming conventions. Every major building element or group of elements should have a corresponding task. This means breaking down activities by floor and by element type/trade wherever appropriate (for example, instead of one task for “RC structural frame – all floors,” use separate tasks for “Cast ground floor columns,” “Cast 1st floor columns,” “Cast ground floor slabs,” etc.). The WBS should extend to multiple levels of detail, not just high-level phases. Moreover, standardize the naming of activities – ideally include a code or reference in each task name that corresponds to the cost breakdown or a classification system. For instance, tasks could include CSI codes or a custom code that aligns with BoQ items (e.g., an activity “1.2.3 – Install Rebar for Ground Floor Walls” matching a cost item code 1.2.3). This way, there is a one-to-one mapping possibility between schedule tasks and cost items. A well-structured and connected time plan not only eases 4D/5D integration but also improves project control; as noted in the case, effective scheduling can help reduce delays.
- Reorganized Bill of Quantities (Cost Breakdown): Structure the BoQ (or at least the portion used for 5D BIM) in alignment with the model and schedule. Each cost item should correspond to a distinct scope of work that can be directly linked to specific model elements and (if applicable) schedule tasks. To achieve this, separate cost items by element type and floor level. For example, instead of one cost entry for “Concrete works – walls and columns – Ground Floor,” split this into two items: “Concrete works – walls – Ground Floor” and “Concrete works – columns – Ground Floor,” each with its own quantity and unit rate. Do the same for other composite items; reinforcement could be broken down by element and floor (e.g., rebar for ground floor walls, rebar for first floor walls, etc.) rather than by rebar type alone. In addition, enforce a standardized Cost Breakdown Structure with classification codes for all items. Using a recognized system (or a project-specific coding scheme consistent across documents) will enable the BIM model elements, schedule activities, and BoQ lines to share common identifiers. This dramatically improves the ability to automate the linking process – as the case study notes, a classified 3D model combined with classified cost items allows software to match them automatically, whereas unclassified data forces laborious manual linking. By refining the BoQ in this manner, the project’s cost data becomes 5D-ready. Each cost entry is now a smaller, well-defined packet of cost that can attach to the corresponding set of BIM elements and, if applicable, align with a schedule task covering that same scope.
- Integrated Data Environment & Process: Underpinning the above technical steps, we recommend establishing an integrated project data environment and collaboration process. All stakeholders (designers, planners, estimators, contractors) should work towards a unified BIM strategy. Practically, this means regular coordination meetings to align the model, schedule, and BoQ structures; agreeing on common codes/libraries at project outset; and using BIM management tools (like BEXEL Manager or similar) throughout the project lifecycle rather than only at the end. By treating the 3D model, schedule, and estimate not as separate deliverables but as interlinked parts of one digital project, teams can ensure consistency. The case study guidelines implicitly support this: better project communication and more frequent integration checks were advised to improve model uniformity and reduce errors. In a fully integrated workflow, as soon as a design change occurs, its impact on schedule and cost can be evaluated in the 5D model, and conversely, any schedule or budget change is traceable in the BIM.
By implementing these guidelines, a project like Bužanova-Štrigina can be restructured for optimal 5D BIM integration. Following the above steps would allow the team to import the refined schedule and cost data into the BIM environment, use the enriched 3D model as the common backbone, and achieve automatic or semi-automatic linking. The end result is that all three dimensions (geometry, time, cost) become synchronized. In the case study, the recommended procedure was: import the adjusted time plan and CBS into the BIM software, establish selection sets in the model that correspond to the schedule activities and cost items, link those sets to tasks and costs, then let the software compute the quantity take-offs and costs per task, finally running a 5D simulation that shows the project build-out over time with accumulating costs.
Impact of Applying 5D BIM
Adopting the above recommendations yields significant benefits for project delivery. By aligning the BIM model, schedule, and BoQ, the project team can leverage the full power of 5D BIM for monitoring and decision-making. Integration brings clarity and efficiency: in our case study analysis, it became evident that when any component of the BIM workflow is flawed, the entire process and results are affected. Conversely, when each component is optimized and harmonized with the others, the outcomes improve dramatically.
Key impacts of achieving an optimal 5D BIM integration include:
- Accurate 5D Simulation and Forecasting: With a properly linked model, the project management team can perform 5D simulations that visually and quantitatively track progress and expenditures over time. This allows for developing precise cost and schedule forecasts that align closely with actual project requirementsp. For example, the team can simulate the construction sequence and automatically see the budget usage and remaining value at each timeline milestone. This capability significantly streamlines the estimation and project control process, enabling proactive adjustments if a potential delay or cost overrun is detected.
- Reduced Errors and Rework: Implementing the guidelines minimizes human error in linking data. For instance, standardizing classification across the model and BoQ removes the need for guesswork or manual matching of items, thereby reducing the chance of mistakes. In our case, if the reinforcement cost items had been broken down by floor and element, the tedious manual filtering that led to incorrect or missed links would be eliminated. Furthermore, a coordinated model (free of internal clashes) prevents costly on-site issues and redesigns.
- Improved Team Collaboration: The process of aligning model, schedule, and cost data inherently brings different project stakeholders onto the same page. When architects, engineers, schedulers, and cost estimators follow a shared framework (like common breakdown structures and data standards), communication improves. The Bužanova case showed that a lack of collaboration led to each team producing outputs that didn’t fit together, which is unfortunately common in traditional workflows. By using the 5D BIM integration approach, the project fosters a culture where everyone is aware of how their work affects others. For example, the planner knows how the estimate is structured and ensures the schedule reflects that structure; the estimator understands how the model is built and can align the costing to its elements. This streamlined collaboration can shorten the time needed for cross-disciplinary reviews and ensure that as the project progresses, all data remains consistent.
- Enhanced Project Outcomes: Ultimately, the integration of the 5D BIM model has tangible impacts on project outcomes. A well-synchronized 5D model allows more effective monitoring and control, as noted by the case study: a structured plan and linked data reduce the chances of unforeseen delays. Project managers can quickly generate reports on progress vs. budget, owners can visualize how and where money is being spent, and contractors can plan site logistics with better insight from the 4D sequence. In the context of the Bužanova-Štrigina project, such integration would mean the investor and contractors have a single source of truth – the 5D model – to consult for any questions about “when” and “how much” for each part of the build. This leads to higher confidence in decision-making.
Conclusion
This report underscores that successful 5D BIM is not merely a software exercise but a matter of coordinating people, processes, and data. Even a small inconsistency in one component (design, schedule, or cost) can ripple through and undermine the entire integrated model. Achieving true 5D integration requires a strategic approach where multidisciplinary collaboration, standardized data structures, and continuous quality control are embedded into the project workflow from the outset. Without this foundation, the benefits of 5D BIM—such as precise forecasting, better risk management, and enhanced project control—remain out of reach.
