Added value through BIM workflow in practice – presentation by Tim David Lemmler and René Seifert on the tried-and-tested workflow á la ‘keep it simple’.
At BIM World Munich, 2025, Tim David Lemmler and René Seifert from Canal Architektur +Generalplanung presented their successful, tried-and-tested workflow for model-based cost calculation and tendering. The focus was on the seamless and efficient collaboration between their CAD tool Allplan and the tendering software NOVA AVA. They demonstrated how the consistent use of attributes and intelligent filters allows the greatest possible added value to be extracted from the 3D model – a perfect example of BIM in action with Allplan and NOVA AVA.
The recently completed Frames Hotel in Mülheim-Kärlich served as a practical example, where the office demonstrated how planning quality and cost certainty go hand in hand from the early phases to the finished Bill of Quantities (BOQ).
“Keep it simple” for BIM success Attributes instead of complex geometry
The foundation for a smooth BIM process is laid as early as the architectural planning stage. Von Canal’s approach is consistent: “Keep it simple”. Instead of modeling each component with complex, multi-layered geometries, the effort is deliberately concentrated on enriching the information:
- Single-shell modeling: Elements such as walls (e.g. drywall, masonry or concrete walls) are only created as single-shell components in the Allplan model. There is a deliberate decision not to model each individual layer (cladding, insulation, stud frame) geometrically.
- Information enrichment by attribute: All specifications required for the subsequent tender and cost calculation are instead added to the single-shell geometry as attributes.
These include- Materiality and building physics
- Fire resistance class
- Sound insulation class
- Information on additional design details, e.g. whether a sliding ceiling connection is required.
- Assured quality through wizards: The key to consistency is the use of self-developed Allplan wizards, which are available to all employees and contain all relevant attributes already preset. This minimizes errors and creates the basis for a “cleanly constructed 3D model”, which is essential for BIM with Allplan and NOVA AVA.
Intelligent filtering: The central key in NOVA AVA
The IFC model exported from Allplan contains a large amount of information. To make this data usable for DIN and VOB processes, the creation of filters in NOVA AVA is the most important parameter. The filters are used to assign the components step by step and precisely to the desired cost or BOQ items.
Using the example of drywall, the speakers explain the detailed, seven-stage filtering process that von Canal has opted for in NOVA AVA:
- Base: All elements of the model are included in the filter.
- Component type: Only walls are filtered out; all other elements are removed.
- Rough exclusion: All exterior wall components and load-bearing walls are removed, as only interior walls are relevant for the drywall construction trade.
- Trade: The system filters specifically for the trade “Drywall work”.
- Construction type: Differentiation by supporting structure, e.g. filtering by metal stud frame (to exclude timber stud frame, if relevant).
- Detail: Further differentiation, e.g. according to shaft walls or walls planked on both sides.
- Dimension: The final filtering is carried out according to the wall thickness (e.g. 15 cm).
This filter chain is the central prerequisite for precise quantity takeoff. The filter palette in NOVA AVA offers the option of displaying the filtered components visually in the 3D model at any time, which allows for quick plausibility checks and visual control.
Cost calculation and VOB-compliant quantity takeoff
The BIM workflow with Allplan and NOVA AVA enables a seamless link between the model and the commercial processes. Model-based cost calculation according to DIN 276.
After importing the IFC structure, cost elements are created in NOVA AVA. These contain individual costs (e.g. price per cubic meter of concrete, square meter of formwork) and are assigned to a service area and the appropriate DIN cost group. Each cost element is linked to the corresponding component in the model using the previously defined filters. The result is a model-based cost calculation that is structured according to DIN and provides the necessary level of detail for budget control and cost estimation in the early phases.
Secured quantity export and VOB special cases
In contrast to some other BIM workflows, von Canal relies on secure quantity export for the tender. The BOQ is not generated automatically, as the export from the model is not yet considered secure enough for this.
The highlight lies in the mapping of VOB-compliant quantities and allowances, which did not have to be modeled:
- VOB quantities: As Allplan does not map all VOB rules (such as the non-deductibility of small openings) during IFC export, an additional filter was constructed. This identifies all openings in drywalls that are smaller than 2.5 m² and adds these quantities to the net quantities. In this way, VOB-compliant quantities are generated despite the “keep it simple” modeling.
- Non-modeled allowances: Structurally complex but geometrically simple elements such as the allowance for a sliding ceiling connection (which would usually require a separate, complex component) are also mapped using filters. An attribute filter identifies walls with the attribute “floating ceiling connection”, reads the length of the wall from the geometry data and uses this to generate the corresponding allowance item in the BOQ.
Conclusion: speed and control as decisive competitive advantages
The consistent use of BIM with Allplan and NOVA AVA has led to a highly parametric process chain for von Canal Architekten, the benefits of which go far beyond mere quantity takeoff:
| Advantage | Quantifiable benefits |
| Consistent quantities | All quantities are based on the quantities of the BIM model or on quantities derived from it using a formula. These quantities, which are in fact derived entirely from the models, are always linked to the cost calculation and all Bill of Quantities. |
| Plausibility check through visual inspection | Quantities, components, filters, … – all these values and elements can be visually checked for plausibility using the BIM model viewer. |
| Parametric process chain generates efficiency for repeat projects | For projects with the same equipment qualities, up to 75% of the cost calculation can be completed with just one click. |
| Only 15 minutes to update quantities and costs | Model changes (which occur constantly in the planning phase) are processed quickly. The entire process (cost calculation and BOQ) is updated within just 15 minutes. |
| Interface becomes an interface that employees don’t want to miss | The employees now perceive the connection as an “interface”. They actively prefer and demand this clean, model-based approach over older 2D methods. |
The speakers’ two most important mottoes for BIM with Allplan and NOVA AVA are therefore: “Think processes from the end” and “Keep it simple“. These currencies enable an efficient, consistent, model-based approach that covers all phases from the early estimate to the tender.
In this way, buildings can be realized as they are designed and budgets can be reliably controlled.
Further information on BIM workflow with Allplan and NOVA AVA can be found in the guide “Allplan and NOVA AVA – Notes on the BIM workflow“
See more about having fun with NOVA AVA and construction cost management at von Canal Architecture + General Planning