Why BPS Engineers Waste 50% of Their Time on Remodeling (And How We Solve It)

Building Performance Simulation (BPS) should optimize building energy efficiency. Instead, simulation engineers spend up to half their project time on one of the most frustrating tasks imaginable: manually remodeling geometry.

Years ago, renowned BIM pioneer Vladimir Bazjanac captured the problem in his publication Acquisition of building geometry in the simulation of energy performance:

“The current practice of preparing inputs for energy simulations typically involves repetitive, manual steps that essentially duplicate data that already exists. The process is error-prone [...]. As building complexity increases, input preparation becomes the main catalyst for abandoning (or never starting) the simulation project.”

Although BIM (Building Information Modeling) promised to solve exactly this, the problem remained unresolved until recently. Our market analysis shows that 25 to 50 percent of total simulation effort still flows into manual remodeling.

Why is that? And how does abstractBIM solve this problem technologically—once and for all?

The Problem: Geometry Anarchy in IFC Models

An architectural model is not a simulation model. The same exterior wall can be modeled in dozens of completely different ways in a BIM file—and each can be “correct” for the architect's use case:

• Variant A: A single solid geometry for the entire wall thickness.
• Variant B: Each layer (insulation, brick, render) modeled as a separate standalone element.
• Variant C: Extremely detailed constructions including screws, brackets, and rails.
• Variant D: The wall incorrectly declared as a vertical slab element.

For thermal building simulation (BPS), these inconsistencies are poison. Simulation software needs clean thermal zones, clearly defined space boundaries, and unambiguous geometry relationships. The result? The building physicist starts over and redraws the model manually in simulation software like IDA ICE, DesignBuilder, or EnergyPlus.

The Solution: The Abstract Normalizer Algorithm

When we built abstractBIM, we wanted to end this “BIM bullshit”. We asked: Is there an element in the IFC model that is almost always modeled highly consistently and correctly?

The answer: The space (IfcSpace).

Architects model rooms almost always precisely because they need them for room programs, area calculations, and lease plans. Windows and doors are usually clean too, since they are inserted via standardized software tools.

Our Abstract Normalizer algorithm uses exactly this consistent data foundation and flips the principle:

• Room-centered analysis: The algorithm looks primarily not at the wall, but at the empty space between IfcSpace elements.
• Automatic abstraction: From inconsistent, chaotic wall geometries, the algorithm computes a perfectly normalized, consistent geometry model.
• Seamless export: The result exports directly to formats your simulation software understands: IFC, gbXML, or Excel.

[Inconsistent architectural BIM]
        ↓
        [Abstract Normalizer (uses IfcSpace)]
        ↓
        [Perfectly structured BPS input model (gbXML / IFC)]

Stop Remodeling: Focus on Real Engineering Work

The technological nut is cracked. The problem of manual remodeling is solved. Now it is up to the industry to use this tool so simulation engineers can finally do what they are paid for: design better, more sustainable, and more energy-efficient buildings—instead of correcting architects' geometry errors.

Share this guide with colleagues in building physics and energy planning—it will make their lives easier.

Learn more about the Normalizer on abstract.build and try automated BPS preparation on abstractBIM.