Orientation of the facades
The orientation of every wall and window comes from the geometry: ifctrano measures the outward normal of each
surface from the north axis of the model (+y by default) and converts it to the azimuth of the Modelica libraries
(see How ifctrano works). This example shows its effect on the simulated
temperatures: the same house, without heating, as built and turned by 180°.
The kitchen of ExampleHOM has windows on its south and west facades. Turning the north axis by 180° makes them face north and east.
from pathlib import Path
from ifctrano.base import Vector
from ifctrano.building import Building
building = Building.from_ifc(Path("ExampleHOM.ifc"))
as_built = building.to_config()
turned = building.to_config(north_axis=Vector(x=0, y=-1, z=0))
north_axis is the direction of north in the coordinates of the model: Vector(x=0, y=-1, z=0) puts north along
-y. Both configurations are simulated from 21 March, when the sun is low enough for the facades to make a
difference, in the Uccle weather.
Days 83 to 90 of the year (the first 2 simulated days are a warm-up and are left out).
| Case | Zone | Mean [°C] | Minimum [°C] | Maximum [°C] |
|---|---|---|---|---|
| As built (kitchen windows south and west) | Kitchen5 | 24.8 | 15.2 | 39.4 |
| Turned by 180° (north and east) | Kitchen5 | 22.7 | 13.8 | 32.1 |
What to expect. In late March the sun is low in the south during the day and sets in the west: a room with south and west windows gets much more solar gain than the same room facing north and east, which only sees the morning sun on its east window.
What the simulation shows. As built, the kitchen averages 24.8 °C over days 83 to 90, peaking at about 39 °C in the afternoons. Turned by 180°, it averages 22.7 °C (2.1 K less) and peaks at about 32 °C. The night minima differ less (15.2 °C and 13.8 °C): the difference is the solar gain of the day. The peaks are high because the house has no heating, no shading and no thermal mass (the default materials, see the limitations).
Difference with earlier versions. Before ifctrano 0.15 the azimuths were turned by 180°: the "as built" case of this page was then simulated as the "turned" one.