Bldg-sim Digest, Vol 19, Issue 17

1 post / 0 new


I've responded to your questions below:

Hi All,
I am curious about how much people are currently utilizing the gbxml
interface for importing of the room and envelope data into their energy
The kinds of feedback/opinions I'm looking for are:
Are you using gbxml on none/some/most/all of your energy models? If
we have a Revit model, we're always using GBXML to bring in spaces
into Trace.
Or, are you still finding manual inputting of room and envelope data
to be just as or more efficient...or perhaps less frustrating? Some
people prefer manual input, but it is not feasible on large scale
projects with +2000 rooms. The amount of time would be extraordinary.
What percentage of the models that you work on would you say use
gbxml imports versus manual data inputting? Previously GBXML had
been tried but not utilized because it would give garbage output. Our
engineers did not understand how the program thinks, and how it needs
spaces to be entered to give usable output. I can see us going to
GBXML for load calcs in the near future (>4 months).
Does the size, complexity and budget on the project make a
difference? GBXML will always save time once you have established
your templates (in Trace). I am not familiar with other load / energy
programs, but I'm sure they all allow you to create templates for
rooms, airflows, Tstats, internal loads etc. Establishing accurate
and comprehensive templates is critical to keep consistency through
projects, and for decreasing time on projects when GBXML is
Does the design phase in which you start the energy modeling make a
difference? For SD, I'd use Ecotect, or create rooms manually. DD's
makes sense to start using GBXML and inputting construction types,
people counts etc.
Are the architects you are working with even constructing BIM type
models that you can get the gbxml files from? If so, are they
constructing clean/tight models that produce good gbxml files for
energy analysis? 90% of our architects in and out of house are in
Revit now, all models will require some 'cleaning up'. This usually
can be done quickly once you know how to modify a architectural
central file to give you accurate thermal zones.
If you know the arch's are going to be constructing a BIM model, does
it influence what energy modeling software you use on the project? I
would say no. I have only been using Trace, however it has huge
limitations energy wise, their support is a brick wall, it took me
less than a year to know more than they know about how their program
works, documentation is missing, etc etc. I like having a complete
control over the model no matter what type of building, or phase it
is in. Specifically I'm working on a large hospital complex, Trace
will not allow for fully exhausting air from any room unless you set
that room to be served by 100% OA, many of these rooms only need 2 OA
ACs and 10 total ACs. Adding 8 OA ACs will increase many energy
parameters and give you inaccurate results.. However Trace is a good
program for load calcs, and does have many system configuration
options available.

Would love to hear your thoughts and experience about the current state of
things and if you are seeing things change in your part of the world.

Thanks in advance for your feedback.

Shariq_Ali at's picture
Joined: 2011-10-01
Reputation: 200