Hi
I wanted to see how IFCtoIDF performs, so I
drew a small building and tried to write extra parameters for EnergyPlus run. I
have the following results.
Description of the building:
Origin of the
building is at (0,0,0) in line with True North. Dimensions
are: 6m (inclusive), 6m (inclusive), 2.7m(Height).
Inclusive means that the dimension is from one face to the opposite one. No
System is defined at the moment. I am interested to see how Geometry is
transferred.
Process:
Drawing done in
ArchiCAD v7.0 -> File saved as IFC 2.0 -> IDF file written via BS-Pro IFCtoIDF utility->Simulation ran in E+ to see DXF file.
Observations:
DXF Output file
looks like figure 01. Please note that, yellow line is for roof slab outline,
Gray is floor slab, Green is wall and Turquoise is for windows. From first
observation it seems that –
Figure 01 – DXF output from IFCtoIDF
after E+ Run.
a. Walls are not connected but have an offset of 0.19m (Half
the width of the Wall – 0.38 m).
QUESTION:
Will that be a
problem in E+ simulations, if walls are not connected? There’s a gap of
0.19m between walls and floor/ roof. My understanding is that, EnergyPlus is
not like nodal simulation (like CFD), so it probably takes in only Area and
Volume to calculate. In this case it does not matter if the walls/ slabs are
not connected to each other. Am I right?
NOTE: I tried to
define zone in different ways (ArchiCAD has 3 ways to define a zone) –
Every procedure gives me the same result.
b. If you take a closer look at figure 2 (bit rotated in
AutoCAD to view the triangulation), you will see that both the slabs (floor/
roof) are triangulated instead of rectangular profile.
QUESTION:
Is
that a glitch in BSPro/ IFCtoIDF?
Just curious. Did anybody face similar problem?
Figure 02: Rotated using 3D Orbit in SW Isometric view. Note the traingulation
NOTE: I guess, BSPro took wall centreline (cL) as the wall plane. But zones are created from inside
dimensions of the wall.
I have corrected the
coordinates (vertices) manually so that it looks like figure 03. Well, changing
tens of coordinates for this file was tiresome but possible. What if – I have
a big building, consisting of a number of zones and hundreds and thousands of
vertices?
Figure 03: Vertices are edited manually so that the walls and slabs are
all connected.
Will I have any
trouble if I use the IDF file (figure 01, 02 - without any editing) and use it
in simulation/ Do I have to edit the vertices so that
they are connected?
Thanks in advance.
Monjur
***************************************
Monjur M Mourshed
IRUSE
Informatics Research Unit for Sustainable
Engineering
Web: http://www.ecaad.com/monjur
http://www.ucc.ie/iruse/monjur
Email : m.mourshed@xxxxxxxxxxx
***************************************
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