[BLDG-SIM] gbXML CAD data into eQuest?

[John F. Kennedy]

All,
 
We have been working with Brandon on the issues he has been having with
the ABS-gbXML-GBS-DOE-2.2-eQuest process flow and would like to note a
few items for clarity.
 
1. The DOE-2 and EnergyPlus files created by GBS are exact translations
of what is in the gbXML file exported by the CAD application. No
surfaces are added, modified, or moved.  The "misplaced" roof Jeff
mentions is actually a ceiling surface that has been exported as a roof
surface from ABS, and we have encouraged Brandon to report the issue to
Autodesk who is aggressively working on any issues with their gbXML
export that are reported to them by their users.
 
2. Jeff and I have spoken about the issues of viewing GBS created DOE-2
files in eQuest's 2D views and have agreed to work together to find a
solution.  The issue in a nut shell, eQuest's 2D plan view relies on
horizontal planar polygons that represent the space boundary and a
planar polygon to represent the bounding story polygon to draw the
spaces and story. That is the primary purpose of these two polygons
(space and floor) as they are not required by DOE-2 for the energy
analysis. A real world example of this horizontal planar polygon
limitation is a theatre floor or a lecture auditorium that have curved
or angled floors that currently can not be viewed in eQuest's 2D view.
The curved or angled floors are represented in gbXML as they are seen in
the CAD application and the resulting GBS created DOE-2.2 files. We have
designed our gbXML to DOE-2 translation for these real world scenarios.
 
3. gbXML does have a volumetric space representation, one that is fully
3D. The vast majority of CAD applications do not have 3D space/room
objects that can capture a curvatous room that you may find in a Gehry
building design with walls tilted outward (that is why Gehry went with
Catia a mechanical design CAD application).  The CAD vendors are rapidly
expanding their tool's capabilities to have fully 3D space objects.
DOE-2, eQuest, or EnergyPlus have no 3D volumetric space objects.
 
One of the tests we recommend CAD vendors conduct in testing their gbXML
export is a sphere. The link below is to such a sphere that has been
translated to DOE-2 by GBS and is viewed in eQuest's 3D view. This
spherical space can not be viewed in eQuest's 2D view, as it would be
too great of a simplification to represent the curved floor with one
planar polygon as eQuest currently requires for its 2D view. It would
also be very difficult programmatically and error prone to automatically
determine where the 2D planar polygon should be.
 
http://development.greenbuildingstudio.com/images/equestsphere.jpg
 
Though none of what I said above will help Brandon's issue today, I
think his feedback to Autodesk, Green Building Studio, and Jeff will
ensure that our next or future updates and versions meet his real needs.
 
Lastly, today the vast majority of energy modeling requires hours of
human interpretation of drawings and CAD models to build the energy
model. In this process, human interpretation makes apprenticed judgments
to simplify the model given the budgetary and time constraints of the
project. The CAD vendors are pushing the envelope to automate this
process to provide geometrically accurate thermal models of the building
as they are represented in their tools. They have made great progress
and are fine tuning the exceptions as they are reported, so very soon we
can shelve our architectural scales as slide rulers were many decades
ago.
 
I look forward to that day!
 
John
 
John F. Kennedy
President & CTO

Green Building Studio, Inc.
www.greenbuildingstudio.com <http://www.greenbuildingstudio.com/> 
707.569.7373 x100 v
707.569.7313 f
707.235.1335 c 
 

________________________________

From: BLDG-SIM at GARD.COM [mailto:BLDG-SIM at GARD.COM] On Behalf Of Brandon
Nichols
Sent: Wednesday, August 30, 2006 9:19 AM
To: BLDG-SIM at GARD.COM
Subject: [BLDG-SIM] gbXML CAD data into eQuest?


All,
 
Recently I have been successful on a number of projects exporting gbXML
building geometry from CAD (Autodesk Building Systems 2007) and
importing into version 6 of Trace 700 and version 4.3 of Carrier HAP.  
 
Have also tried sending the gbXML to Green Building Studio and
downloading the DOE-2 file they create in an effort to import this data
expeditiously into eQuest.  Unfortunately the DOE-2 file created by
Green Building studio is problematic for use in eQuest -- Jeff Hirsch
has looked at one made the following evaluation:
 
It appears that the ACad -> gbXML software creates a building model that
is not easily used in eQUEST and cannot ever be used in the eQUEST
wizard, only in the detail mode. Since it uses an "Energy Plus" style of
input model description (i.e; surface geometry but no floor plan or
space layout) it is not really compatible with eQUEST for detail
envelope or space/zone modification without some difficulty ... since
you cannot use eQUEST 2-d view (the primary way of identifying and
modifying space/zone data.)

Also, the building geometry is not correct and is difficult to really
confirm in eQUEST ... all the interior and exterior walls extend outside
the roof or the roofs are misplaced at Z low by a couple feet.

Since the creation process does not create any space (room geometry) but
only physically places walls at the site relative the location of the
building on the earth (i.e, it does not geometrically describe the
spaces so that they can be viewed in 2- and 3- dimensions, checking the
placement of walls is not possible (but there are visual problems such
as the wall height I mentioned earlier.)

 
Does anyone know of an expeditious way to transfer gbXML geometry data
into eQuest accurately -- being able use the wizards I could live
without, so long as space / zone modification possible in detail edit
mode.  Or alternatively, does anyone know if gbXML import is "in the
works" for a future version of eQuest?
 
Thanks
 
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS

600 Stewart Street

Suite 1000

Seattle, WA 98101

www.hargis.biz

 

d | 206.436.0400  c | 206.228.8707

o | 206.448.3376  f  | 206.448.4450

 
 

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