scaling factor for geometry in CONTAM

[yan8...@gmail.com]

Hi, 

I wonder if there is a scaling factor for geometry in CONTAM such that the floor area for all zones in one building can be easily increased/ decreased simultaneously? For example, I already have a CONTAM model, but I'd like to shrink this building floor area to 2/3 (i.e., reduce the length and width of each room by 1/3) to create another model without having to do everything from scratch.

Regards

Yan

[David Lorenzetti]

Yan,

As far as I know, there is no perfect scale factor for this use-case.

There is a "pseudo-geometry" scale factor, which controls how each pixel on the drawn building model relates to dimensions.  If I remember correctly, when you re-set that scale factor, CONTAM will ask if you want to adjust the zone volumes accordingly.  But even if that works as expected, making this work properly for your use-case probably would require that you drew the original zone outlines roughly to scale.

If I was going to do this, I would probably just open the PRJ file in a text editor, and update the zone volumes manually.  Look for the zone definition section.  It will have a header that looks something like this:

-999
14 ! zones:
! Z#  f  s#  c#  k#  l#  relHt    Vol  T0  P0  name  ...

(except the "14" in the second line will show the number of zones in your project).

Then under the "Vol" column, you can adjust all the entries as desired.  By the way, if the numbers shown in that column don't match those on the screen when you edit the project, it's because of a unit conversion -- the PRJ always stores things in its preferred units, which I think here will be [m3].

As with any time I manually update a PRJ, I would take a few precautions:  (1) save your original file so you don't lose all your work in case you mess something up; and (2) re-open the edited file with CONTAM-W, and spot-check a few of the updated values, to make sure you did things correctly.

-Dave

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[Stuart Dols]

Yan,

I'm assuming from previous conversations that you are working with coupling between CONTAM and EnergyPlus using the 3DExporter. 

You can change the scaling factor as desired then rerun the 3DExporter. Do this in a separate directory. This will generate an IDF with new dimensions. You can run a simulation of this model to obtain the new zone volumes from EnergyPlus output files, e.g., HTML table file, to ensure they are as desired.

Once you are satisfied with the new dimensions, you then need to copy or merge the geometry sections of this new IDF with your previous IDF.

Now you can modify a copy of the PRJ to set the zone volumes as explained by Dave.

As per previous discussions, you need to copy the final version of the PRJ to contam.prj and place into the contam.fmu file.

NOTE: all this assumes that no other changes were made to the "rescaled" PRJ that would cause changes to the VEF and XML files generated by 3DExporter.

- Stuart