Two zones model
This tutorial generates the Modelica model of a small building with two spaces, simulates it and reads the results.
The IFC file, TwoZones.ifc, is in tests/models/space_boundary of the repository.
Generate the model
from pathlib import Path
from ifctrano.building import Building
building = Building.from_ifc(Path("TwoZones.ifc"))
building.show() # space boundaries computed from the geometry
building.save_model() # TwoZones.mo next to the IFC file, for the Buildings library
building.show() displays the space boundaries ifctrano derived from the geometry: the surfaces each space shares
with the walls, slabs, roof and windows around it, and with the other space.
The same from the command line (ifctrano create --help lists the options):
The model opens in OpenModelica (or Dymola) once the Buildings library is loaded. The diagram below was taken with an earlier version; the layout of the components may differ.
Simulate
With Docker running, --simulate-model simulates the model in OpenModelica and opens an HTML report of the results:
Results
The building has no heating model, so the zones are free-floating: their temperature results from the losses through the envelope, the solar gains through the windows and the internal gains of the occupants. The figure shows the first ten days of January in Uccle (trano's default weather).
Days 3 to 10 of the year (the first 2 simulated days are a warm-up and are left out).
| Case | Zone | Mean [°C] | Minimum [°C] | Maximum [°C] |
|---|---|---|---|---|
| Two zones | 01 (dup) | 8.1 | 5.8 | 11.3 |
| Two zones | 01 (uj9) | 9.7 | 6.1 | 17.3 |
| Two zones | Mean of the zones | 8.9 | 6.0 | 13.9 |
What to expect. Without heating, the zones settle between the outdoor temperature (dotted line) and the comfort
range: the envelope loses heat to the outdoor air, while the occupants and the sun bring heat in. Only zone 01 (uj9)
has a window (1 m²), so it warms up more on sunny days.
What the simulation shows. Over days 3 to 10, the mean air temperature of the zones is about 9 °C. The zone with the window averages 9.7 °C and reaches about 17 °C on sunny afternoons; the other averages 8.1 °C and stays within 6 to 11 °C. Both stay well above the outdoor temperature: the default constructions are very insulating (see the limitations).