Modifying Geometry

24 posts / 0 new
Last post

Dear all,

Once again, another problem!

I have several spaces which were geometrically modified in the design. For example, a room that was split into two different ones; with each room being a different hvac zone. How can I possibly split a room into two zones "1" and "2"? Shall I modify the geometry of the old zone to be that of zone "1", and then add another zone "2" from scratch? If this is what should be done, how can I do this accurately?

Attached is the polygon view of one of my floors. When you look at them in 2-D or 3-D views, the building seems perfect in shape. Notice the rectangle to the left of the picture! This is actually a zone that lies inside the building. But it appears like this in polygon view. I think it is some problem of coordinate references or so!
So when I need to modify the geometry according to coordinates of vertices, I'm suffering!

Many thanks!

Omar Katanani

Omar Katanani's picture
Joined: 2011-09-30
Reputation: 0


Your geometry is indeed suffering! Is this the same building, the school,
you have been working on for awhile? Have you taken any training or read the
online help manuals? I am not trying to be rude but the picture you sent
indicates many problems, some of which you seem to be aware of, some which
you don't. Those are the problems I am really worried about. I am willing to
help you, as are many others, but it really looks like you need to either
attend a training class, there's a bunch coming up in August at the IBPSA-US
conference in NY, hire a trainer, or hire someone to work with you as you
learn on this project.

Other than that, your geometry can be modified a few ways: 1) in DD Edit by
modifying your polygons for the space, there are 2 - one for the floor and
one for the ceiling that is automatically created when you create the space.
In this case you will make the existing space smaller and then create a new
one, a "child", that will represent the new space; 2) If you have saved a
copy of your last Wizard files you could use them and then cut and paste the
new data into your existing .inp file, and; 3) make the space/thermal zone
changes directly in your .inp deck using BDL. You should try the first
method or hire someone else to do it for you.

You should definitely hire someone to do a peer review for you when you
complete this project and please consider going to the IBPSA conference and
taking a training. You will learn so much and it will reduce your suffering!

Good Luck,

cmg750's picture
Joined: 2010-10-05
Reputation: 0


The task at hand is definitely not as crazy-hard as it may seem. [edit:
Perhaps if I write a long enough response it will seem difficult?

The key is to have a general understanding of the "tiered" relationship
between surfaces/windows, spaces, zones and systems. Here's a

- Conceptually, I'd first jump to the component tree under the
"building shell" tab, and modify the existing space (to be split)
dimensions, loads, and any surfaces (partitions, exterior walls,
windows, etc.) to be one of the smaller halves. Just go through every
window for the space in the component tree and modify everything as
appropriate. Be sure to modify the loads there as appropriate
(occupancy and so on).

- It'd be smart at this point to name that zone something
recognizable if it's currently "wizard-crypto-babble," for easier

- Then I'd jump to the Airside HVAC tab to find the
corresponding zone, which should remain associated with your modified
space, and fly through that zone's window to make any adjustments
necessary. I'd also rename this for easy identification if you haven't

- Then do the same for the system the zone is tied to, if you
are going to need to "split" the system serving the zone (if it's going
to be served by the same system you shouldn't need to do much of

- With all this set up, you will have a "hole" in your
building. Jump back to the Shell tab and copy the modified zone (right
click, create a new space, copy existing component, select your zone).
This will make everything identical. If you are literally splitting the
zone in two without any changes to the loads and such, you 're done
here, otherwise modify areas/child components (surfaces and such)/loads
as necessary.

- Jump to the airside tab, right click under the appropriate
system, and create a new zone. Give it a clever name also. You'll be
prompted to select an unassigned space after choosing to "copy an
existing component" (your easily-recognizable renamed and modified
zone). Choose the only unassigned space you probably have (the new

- Create a system in the same manner, again only if necessary,
and again modify if it isn't to be an exact copy. If the new zone is
under the same system as the old large zone, just be sure it's assigned
to the right system (it will be obvious from the component tree if it's
in the wrong place).

Before you start this sort of task for the first time, it may be wise to
first read up on and understand what it means to "link" a component
(instead of copying) - it may turn out to be a time/stress saver for you
depending on your current situation.

As to zones/spaces lying "outside" the building, recognize it may likely
be a non-issue in terms of the modeled behavior. If there are no
exterior surfaces, it really doesn't matter as long as everything is
associated correctly (i.e. west interior wall is tied to the correct
space or vice versa). If there are exterior surfaces, just be sure to
think about self-shading effects and reposition to where it should
receive the intended shading behavior with respect to the building
itself and any exterior shades. Elevation (z-coordinate) is something
to verify also, as I suspect that factors into some infiltration calcs
(not personally sure of it, but this is simple to verify).

If you still want to position a rogue-zone back into the building (for
aesthetic reasons or you otherwise feel it's necessary for accuracy),
then you'll need to determine exactly where it needs to move in the
model - hopefully you've kept a copy of the CAD file used to trace the
zones and such, and hopefully you've picked up the habit of always using
x=0,y=0 for origin when importing a CAD file to trace, or can otherwise
backtrack to figure out what you did use... resolving this task is
simply going to require some self-investigation into your files and


Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805


I haven't had much luck with customizing spaces either.

I think there is a way to import a revit model file into equest. If I
needed complicated zones & spatial geometry, I would probably consider a
revit license, but with that come's more money ($4-$6k for 1 standalone
license) and possibly more training, but might save a whole lot of headache.

Seems like equest is more of an energy modeler than an accurate building


tim's picture
Joined: 2011-09-30
Reputation: 0

I have got to protest this one, sorry Tim.

Buying a Revit license to be able to accurately model geometry in eQUEST is,
to be blunt, crazy. It's really pretty easy to revise your geometry and if
you can't do that using one of the 3 methods I provided earlier, you need to
figure out how to train yourself better or leave the field. It's not just a
matter of being able to use eQUEST at this point, it's a matter of being
able to generate an accurate model using any tool. Being able to import CAD
or Revit data into energy models is a recent development. Frankly, I
question it's utility, especially if people now think they have to use it or
they can't model a building. Friendly front ends like eQUEST, DesignBuilder,
etc., are great but you need to know how a building operates and how the
systems work or it's just GIGO.


cmg750's picture
Joined: 2010-10-05
Reputation: 0

Wow - I think I struck a nerve.

On a related note.

Does equest have a way to model individual ceiling heights per room?



tim's picture
Joined: 2011-09-30
Reputation: 0

Well, at least your powers of observation aren't suffering.

Yes, you can model individual ceiling heights per room. You can do almost
anything once you take the time to learn how. What are the specifics of what
you want to do: model a room with two different ceiling heights or model a
bunch of rooms with one height and a bunch with another height? A picture
would be great if ya have one.

cmg750's picture
Joined: 2010-10-05
Reputation: 0

If you're complimenting me on my observation, my awareness must be at an
all-time high today.

How about a complex roof shape like the one attached? Notice ridge lines
don't match and there is a gable at the porch end as well as the building

Can equest do that too? As long as one would put in the training time of


tim's picture
Joined: 2011-09-30
Reputation: 0

You can build any roof geometry imaginable.

You must realize that this is time consuming and makes virtually no
difference in the building model results. I would attempt to keep the
roof simple to avoid wasting a lot of time for little to no change in
energy consumption.

Otto Schwieterman's picture
Joined: 2011-09-30
Reputation: 200


I think eQuest is an energy modeling program and we are more concerned
in BTU/ton terms - or $$ at the end. If the roof was built somewhat
differently by modeler as it was shown on architectural drawings, my
question is only how much it will affect the energy usage. If it is a
minor, I won't drive myself crazy to make them same. If you read Ashare
90-1, simplify building geometry for energy simulation purpose is
allowed. Also when we model a building, we can have tons of inputs and
lots of assumptions are made either by us or by the program itself, I
think majority of them can have a bigger impact on our goal than build a
prefect roof/building shell. I might be one of the lazy modelers. Hope
you can enjoy eQuest a little bit more.


Lan Li, PE

Li, Lan's picture
Joined: 2011-09-30
Reputation: 0

Revit is also very picky. If the person setting up the architectural model does not set it up with load and energy modeling in mind you will spend a lot of time messing with the architectural model before you even get into the MEP model. I don't recommend it yet. Maybe as the design community gets more familiar with Revit and the MEP version becomes more developed it will become a viable option.

Morton, Sarah's picture
Joined: 2011-09-30
Reputation: 200


Yes, you can do complex roofs if you work at it and nobody reminds you
that you're working on a deadline. (See attached.) Ditto Carol's Revit
comment and Lan's simpler-is-better-to-a-point advice.


William Bishop, PE, BEMP, LEED(r) AP

Bishop, Bill2's picture
Joined: 2011-09-30
Reputation: 0

Couldn't agree more. That was my point. equest is an "energy" modeler.
If someone wants to waste their life away learning how to model complex
geometries in equest, that's their choice, but I'm not sure it was meant to
be used that way.

After all, when the program starts up, it says itself in big letters "QUICK
ENERGY SIMULATION TOOL" - the operative word being "QUICK".

Just trying to help out Omar with a little perspective is all, so thanks for
helping to prove my point.


tim's picture
Joined: 2011-09-30
Reputation: 0

Wow Bill - that is cool - thanks for that. Not sure I will be that adept
after my 7000 square foot project, but it's good to know the capabilities.
This building was generated in equest? I did find where you can change the
pitch of the roof by degrees!

I have never use revit with equest btw - I was just reacting bitterly to my
first go at trying to use that interface. I tried to customize zones and
came up with some crazy thing that looked like a tree house for monkeys.

Thanks for helping me believe.


tim's picture
Joined: 2011-09-30
Reputation: 0

To All:

Do not import from REVIT. I use REVIT, ECOTECT, 3DMax and many other
products. If you want to create just geometry objects without building them
in eQuest use ECOTECT or a DXF file from AutoCAD created in 3D. eQuest,
Ecotect and AutoCAD understand and interpolate planar geometry which means
when you create a cylinder you are in fact creating planes that segment a

Short Lesson.

2 ways to create surfaces are either by planar geometry or using nurbs.
Nurbs are algorithims that are complex and it is what you see animators use
to create faces, people etc. buildings are best created using planar
geometries because it simplifies the models. With detail mode in eQuest you
can create these planar surfaces on a grid however it becomes very
complicated on larger projects because you have to keep track of your walls,
roofs and ceiling coordinates from your 0,0,0 origin. This is why using the
wizard with the AutoCAD underlay is so effective.

This is also why objects tessellate when you create compound curves. In
other words doing a Frank Gehry project in eQuest would be quite
challenging. At this point you would probably need to move to a program like
IES or do the calculations by hand.

Back to eQuest.

Go to building shell tab. Scroll down to polygons folder. Right click and
select create new polygon. Fill out all the coordinate information.

Scroll up to where you floor is identified. This is where you need to decide
which space the geometry will belong to. Each space is created by the
AutoCAD layout which you can get to from 2D geometry right clicking on the
screen and selecting switch to polygon view. In polygon view you can create
your different space shapes. These spaces are then where you attach your
polygon too.

These spaces you can use to create HVAC zones with.

Hope this was not too complicated or long winded. I still think it is best
to create your 3D geometries outside of eQuest if they are complicated
import them and then modify spaces in eQuest.



Peter Hillermann2's picture
Joined: 2011-09-30
Reputation: 0


Couldn't help notice - you seem to have the roof modeled as a wall (vertex input) rather than a roof (top of space). Is it simpler to do it that way?

Vikram Sami, LEED AP

Sami, Vikram's picture
Joined: 2011-09-30
Reputation: -1

Wow, I didn't know I would cause all this debate!!

Anyways, I modified a zone that I want to split into 2 non-identical zones. Then I had a hole in my building.
I created a new space and a new polygon. I fitted the polygon into the empty hole as seen in "2D Polygon.jpg".

Then after I returned to the 2D view mode, I discovered that the space is not located properly!! It's 9:45PM and I'm still at the office! This modeling thing is frustrating!

I also attach the eQUEST files, if someone can please help. If someone was very kind to clearly help me sort this zone out, I think I can continue the rest of the building zones modifications in peace!

Many thanks!

Omar Katanani

Omar Katanani's picture
Joined: 2011-09-30
Reputation: 0

Thanks. Yes, eQuest. You do as much as you can in the Wizard. I find I
often have to modify roof surfaces in DD edit mode. I will usually
create a new roof polygon by copying the polygon of a trouble roof
surface, change the coordinates in the .inp file (unless it is a simple
rectangle - I find the program is glitchy when you try to modify
coordinates in a spreadsheet in DD edit mode) and save it, then reopen
the eQuest model and assign the new roof polygon to the roof surface.
Lather, rinse, repeat. Save often.

"Couldn't help notice - you seem to have the roof modeled as a wall
(vertex input) rather than a roof (top of space). Is it simpler to do it
that way?"
Modeling a sloped roof is a judgment call. You have to decide if the
added complexity will give you a significantly better model, or if the
visual "wow" factor is worth it for impressing your clients. The wizard
does a decent job at sloped roofs for simple building geometries. As far
as walls vs. roofs, it seems to me that eQuest models them the same,
except for the angle. (Someone please correct me if I'm wrong.) After
all, you add both walls and roofs in DD edit mode by creating a new
"Exterior Wall". If the building geometry is such that you can simply
select "top" for the surface location (such as the one roof surface on
the first floor of my example), then of course that is easier.


Bishop, Bill2's picture
Joined: 2011-09-30
Reputation: 0

What I usually do when I need to modify geometry is I save a version of
the file and call it "old", then I open that file and the file I am
working on at the same time. You can use the old file to check what
vertices and walls you had for the space after you delete it in your new
file. I think in your case, I probably would have left the space as it
was and then added a space within it. you'd have a big space, then one
inside of it. I'd then adjust the wall lengths and square footage of the
big space so it didn't overlap the other space anymore.

You're biggest problem will be when other spaces reference your old
space as a "next to." When you go into the properties of a wall, you'll
see the wall is sometimes located by what it is "next to". when you move
the old space, you're other spaces around it might get confused. Go into
the spaces immediately surrounding the space you're adjusting and make
sure you put in the newly created room as the "next to" instead of
leaving the old room there.

When you edit a 2-d view, you can type in the location of the vertices
instead of dragging the dots around and trying to get close. Use your
old file as a reference for these vertices. The corners (vertices) of
the two spaces should not be different than your old corners. Does this

Martz, Amanda's picture
Joined: 2011-09-30
Reputation: 0

Yep, I just gave up and rounded off distances and settled for a simplified
roof. After all, there are even slight discrepancies between masonry
coursing dimensions & fractional feet. Besides that, ASHRAE 90.1 G even
says this is not an attempt to model actual energy usage, but rather to
compare against the more widely used, typical systems (baseline).

Attached is an image of the model that equest generated after my compromises
- took about 10 minutes in the wizard - no dd editing.

I believe you with the vertices & the text file editing an all, but if the
point isn't even to model the "actual" energy usage, then I say why bother?
I can make a pretty accurate looking model in revit or sketchup or drawing
by hand for that matter if you just want to look at it, but I'm thinking of
equest as more of a tool just to get close enough to real world to get the
numbers needed to find the percent improvement over the baseline and make
the planet will be a better place to live.

Even equest tutorials say this is "SIMULATION"


tim's picture
Joined: 2011-09-30
Reputation: 0
Thomas Serra's picture
Joined: 2011-09-30
Reputation: 0

Interesting - because sometimes by trying to be too accurate you end up being less so. Tim - in your image, the roof surface overhangs on all side it looks like 2 feet). In reality the solar heat gain on those two feet are not really transmitted to the zone. In your eQUEST model it will be.

It looks like its a plenum zone, so the impact is probably minimal, but its something to watch out for.

Now let's beat this thing a little more and see if it runs....

[cid:image001.jpg at 01CB28E8.94CFA130]

Vikram Sami, LEED AP

Sami, Vikram's picture
Joined: 2011-09-30
Reputation: -1

Why would solar heat gain be transmitted from an eave if I specified
insulation on the attic floor atop drywall ceilings? Wouldn't it assume I
have a vented attic? I think in reality some heat would transfer anyway,
albeit a very small amount.

A bigger question for me is, should I model the windows that will be
infilled with glass block? I suppose I could if I had to since equest does
it all, but again if I'm not even going for a ultra-realistic picture so
much as I am a comparison, why bother? I mean, it would only translate into
a longer modeling process which will only hurt the image of the energy
modeling industry as a whole, right?

I do really like equest by the way for what it's worth and glad to be using/
learning. I am very new to it and I don't mean any disrespect to those who
have spent a long time with this software. My experience is with other 3d
computer modeling programs over the course of the past 15 years and I do
know what it's like to grit it out in the hard times.

I just have always thought there's something kinda funny when we try so hard
to make something inside a little box look so real. There's a beauty in it,
but then somewhere the rubber needs to hit the road as they say.




tim's picture
Joined: 2011-09-30
Reputation: 0


If your glass block is less than 5%, or whatever the % is in App G, then you
can justify ignoring it. Otherwise, I'd check out Win5 to see if they have
data for glass block. You can model your window using it and then import it
into eQUEST.

WRT using CAD or Revit or whatever. I actually watched a client spend about
a day importing his CAD drawing into eQUEST because it had a complex roof
and I swear I could have modeled it by hand in eQUEST faster. It's not that
hard and at the end of the process you know exactly where everything is
because you input the vertices by hand. Old fashioned, I know, but hey, I'm
just saying. When I use the Wizard to input my geometry I use the Above,
Next to, etc., feature and specify my exact location as 0,0,0. That seems to
help with the geometry when I get into DD edit. With the CAD drawing, see
above, I think it might be best to set the location of each shell as 0,24,0
or wherever the vertex actually is. I'd have to double check this.

I love the humor that's coming through lately with the information. Thanks
for the cartoon, Vikram, and the Somebody Stop Me file, Bill.


PS I'll look at your file later Omar. I hope you went to bed by now since
it's after midnight where you are.

cmg750's picture
Joined: 2010-10-05
Reputation: 0