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[BLDG-SIM] gbXML CAD data into eQuest?
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.
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
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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