Multi-disciplinary three-dimensional representations of building designs are available in BIM. However, thermal analysis often remains a manual task due to disparities in modelling: In IFC, buildings are decomposed into sets of elements with individual solid volumes. Thermal analysis requires interfaces between pairs of adjacent spaces.
In this work, we present an end-to-end solution for thermal analysis on IFC building models. We derive thin-walled thermal interfaces from architectural building models using voxelization. Neighboring spaces (separated by wall volumes in IFC) are touching after aligning to the voxel grid. The resulting mesh is converted into OSM files for OpenStudio/EnergyPlus.
This paper provides an implementation, discussion and initial validation. The algorithm depends on a minimal amount of information and favors robustness over accuracy, algorithms on voxels are robust. It is suitable for early design feedback and partial or imperfect scan2bim models.
Thermal analysis of IFC building
models using voxelized geometries
Thomas Krijnen and
Tamer El-Diraby - Theohar Konomi - Ahmed Attalla
Rationale. Current IFC export architecture
slow release cycles
Rationale. Envisioned IFC export architecture
fast release cycles
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
Buildings as decompositions of
Thin-walled thermal interfaces
u (periodic) ⟶
0 1 2 3 4
BIM input Grid overlay
Space voxelization Discontinuities mesh
Associated semantics and projected
sub-surfaces (windows, walls)
Original IFC wall and infill elements
Original IFC space geometries
Voxelized space volumes (now
Exported model in Open Studio
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
Effect of surface increase due to
Future work: automated detection of
(a) voxelized IFC geometries (b) exterior (c) interior as negation of b (d) spaces obtained as c - a
Side step: other voxel use cases
Door direction check
Distance from exterior door
Safety barriers check
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