Thermal analysis of IFC building models using voxelized geometries

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Thermal analysis of IFC building models using voxelized geometries Thomas Krijnen and Tamer El-Diraby - Theohar Konomi - Ahmed Attalla

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Presenter • Thomas Krijnen • Post-doctoral researcher @ TU Delft, NL • Founder AECgeeks • Maintainer IfcOpenShell.org • ✉ [email protected] • 🐤 @aothms • 🖵 speakerdeck.com/aothms

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Rationale. Current IFC export architecture slow release cycles diffuse focus repeated effort no alternatives

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Rationale. Envisioned IFC export architecture fast release cycles focus reduced effort choice

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“ Unix philosophy Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface. ” Douglas McIlroy, Peter H. Salus

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Buildings as decompositions of solid volume products

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Thin-walled thermal interfaces http://nrel.github.io

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Geometry https://doc.cgal.org u (periodic) ⟶ v ⟶ 0 2π 0 1 2 3 4

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Process outline BIM input Grid overlay

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Process outline Space voxelization Discontinuities mesh

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Process outline Simplified mesh Associated semantics and projected sub-surfaces (windows, walls)

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Original IFC wall and infill elements

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Original IFC space geometries

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Voxelized space volumes (now touching)

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Exported model in Open Studio

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Statistics Voxel space volume 58071.25 (464570 × 0.53) IfcSpace volume sum 47257.91 One-sided thermal interface sum 36640.25 IfcWall area sum (length x height) 16683.05 IfcSlab area sum (volume / thickness) 20315.27 IfcWall + IfcSlab area sum 36998.32 Number of IfcSpaces 218 Number of unique boundary sides 208

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Synthetic model

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Effect of surface increase due to staircases

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Future work: automated detection of spaces (a) voxelized IFC geometries (b) exterior (c) interior as negation of b (d) spaces obtained as c - a a) b) c) d)

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Side step: other voxel use cases x y Door direction check Distance from exterior door Headroom check Safety barriers check

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Conclusion IFC as a driver for innovation in modular tools A robust, but less accurate, approach for thermal analysis on building models is presented Voxelization as a “low tech” solution to computational geometry problems in our industry