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B18

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TRNSYS TRNBuild Building.

At a glance
Original creator TRNSYS (University of Wisconsin)
Purpose A TRNSYS building description from TRNBuild: layers, constructions, surfaces, airnodes and zones of the multizone building model.
Extensions .b18
Poka parser poka-b18
Viewer poka-tree-viewer
Depth tier Parser with a shared viewer (see Depth tiers)
Breadth tier B3 Core (see Breadth tiers)

How much Poka reads

B3 Core. Only the main content type or types are decoded (for example geometry but not materials, layers or annotations, or only one version family). The list of gaps is substantial.

Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-16: poka-b18 src/lib.rs (parse_building, build_ast, unit tests), tests/samples.rs and tests/scaling.rs; corpus web-House.b18 (TRNBuild 3.0.298, 506 lines, 2 zones), the only sample. Compared with the file contents directly. Read: zones, airnodes and surfaces with adjacency checks, constructions with layers and thicknesses (plus layer conductivity), counts for the library blocks, and the extension blocks after END as line counts only.

What Poka does not read

  • airnode REGIME data is parsed and dropped: internal gains with schedule scaling, heating and cooling setpoint assignments, capacitance, volume, reference area and initial conditions
  • INFILTRATION, VENTILATION, COMFORT and DAYLIGHT definitions are recognised as block names but discarded
  • SCHEDULE contents (hours and values, day-type tables), GAIN, HEATING and COOLING definitions: only counted
  • WINDOW library entries: only counted (glazing properties are not shown)
  • layer properties other than conductivity (capacity, density) and construction properties (absorptance, emissivity, film coefficients)
  • the 3-D building geometry in the BuildingGeometry extension (vertex and surface lists) is counted, not decoded or drawn
  • external shading, daylight sensor points and Berkeley WINDOW pool are counted only
  • PROPERTIES, OUTPUTS and ORIENTATIONS sections are not shown beyond a count
  • radiation and daylight mode settings per zone
  • lists are capped at 200 zones, surfaces or constructions

Background

TRNSYS is a commercial simulation program for renewable energy and building simulation, developed at the University of Wisconsin. A deck (.dck) uses a .b18 file when it instantiates Type 56, the multizone building. Poka shows the building as a tree from zones to airnodes, surfaces and constructions, and the layers each construction is made of. The keyword END does not end the file, so the reader does not stop there.

Versions

Version Identifier Poka Note
TRNBuild building description Read

Sources