Re: [EnergyPlus_Support] IFC to IDF, Geometry, Relative coordinates

[Linda Lawrie <linda@xxxxxxxxxx>]

At 05:16 AM 11/29/2002, Monjur M Mourshed wrote:

> 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?

It should not be a problem for EnergyPlus.  It might be....if you
specify Solar Distribution as FullInteriorAndExterior, but I'm not sure
about that.

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?

I don't know the answer to that one.  I'd suggest looking in the
IFCtoIDF manual to see if it is covered there.  That is, it may not
be a glitch but rather a feature -- to triangulate all "flat"
surfacs would allow for non-rectangular zones to be handled the way
EnergyPlus might need them automatically but will make things a bit
strange for the simple, rectangular zones.

(You could try making an L-shaped zone and see if the floor comes out
looking reasonably correct and goes into EnergyPlus correctly).

>  
>
> 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.

There may be an option in Archicad and/or the app that reads the IFC file
that would change this interpretation of centerline vs. inside dimension
vs. outside dimenion use?

>  
>
> 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?



> 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?

As I said above, you really should have no problem. 

Linda

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