[Equest-users] Expression Evaluation Error
Bruce Easterbrook
bruce5 at bellnet.ca
Fri Aug 23 06:54:28 PDT 2013
In that case I would do a major simplification of the zoning based on
the AHU systems. Interior walls inside a zone won't have much impact and
I would leave them out. What I have found with the zones not lining up
properly is in some cases the model will freeze and not even run. Or it
generates pages of errors. Once the points/walls are lined up the
errors go away. What is left is criticaland the noise is gone.
Energy studies are a totally different ball game on existing buildings.
Typically the first thing you will have to do is get your model running
similar to the buildings current performance. You will probably find
that even more difficult. There is lots of discussion on that as well
in the archives. Have fun.
Bruce
On 23/08/2013 09:04 AM, Eric O'Neill wrote:
>
> Thanks Bruce, I hear ya. In this particular case, this model is for an
> existing building energy study, where the owner actually has nearly up
> to date as-built dwgs (!), so I think we're talking apples and
> oranges. It's a hospital (nearly all clinic and office spaces are out
> of scope and have been excluded from the model) and it seems that
> almost all AHU's have spaces that require continuous space pressure
> relationship requirements, so one of the measures we're looking at is
> doing some unoccupied airflow reductions in specific areas, which is
> why I've done a more detailed zoning. However, zones don't currently
> have temperature setbacks and on this project we're not planning on
> recommending that, so my gut says there's not enough heat transfer
> between spaces at similar temperatures to justify spending the time
> making sure everything lines up perfectly. Bad assumption? Maybe I'll
> test it out at some point when I get a chance.
>
> Eric L. O'Neill, P.E., LEED AP
> Direct 608.785.3328 |Michaels Energy
>
> *From:*Bruce Easterbrook [mailto:bruce5 at bellnet.ca]
> *Sent:* Thursday, August 22, 2013 9:59 PM
> *To:* Eric O'Neill
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Expression Evaluation Error
>
> It will matter and in ways you don't realize. It did generate
> errors. Just because you can get equest to run doesn't mean it is
> giving you accurate data. If you have an interior wall between the
> zone you thought was against an exterior wall then you are not getting
> proper timed heat transfer into that space from the exterior wall.
> You will also have a space which is not conditioned that will generate
> under heated/cooled hours because you don't know it is there. The
> general heat loss/gain through the exteriors walls will be reasonably
> accurate but your ability to keep the interior spaces under control
> will be compromised. You aren't sure what you have, adiabatic,
> interior, exterior? What about air walls?
> I suppose my main point is efficiency and approach to whatever problem
> you want data on. You did a fair bit of work tracing in many of the
> interior walls. Why do that if you don't need to? Just put in the
> perimeter and let equest auto zone it, auto size it for you, press the
> button and you are done. Part of using equest, before you get
> inputting data, is to determine what you want out of it. If you have
> a simple request for a general basic heat loss/gain then simplify your
> model in ways you can minimize the work you put in to get you the
> results you want. Keep in mind also that if the project continues on,
> the questions will get more pointed and complicated. So with that in
> mind keep copies, still in the wizards, you can go back to later and
> refine further. If you want a ball park, do a ball park. A few hours
> with a spread sheet can do that. The other thing that happens is when
> you pass this information on other designers they will refine their
> design, thoughts and almost surely make changes. When they lob one
> back into your court it might be totally different so you don't want
> to have a ton of work into your model that doesn't accomplish
> anything, but you want to be set up so you can maximize what you have
> done and use it going forward. One thing you can bet on is the
> architect has sold the building on the street view. The perimeter is
> going to be pretty much fixed. The interior floor plan fairly fixed.
> As for zoning and how to heat and cool the space, totally wide open
> with ASHRAE 90.x in mind.
> Modelling was an extra, which is becoming a requirement and soon to be
> a must. No one wants to pay for it or pay what it is worth. Your
> modelling has to be as efficient as the building you are designing.
> Taking an hour, maybe 2, at the start, looking at the building and the
> questions the other members of the team are asking and refining your
> approach is time well spent. Even a simple model will take days to
> get input, running, debugged and checked. An input error might take
> days to figure out and you are over budget. It is the foundation to
> the whole process.
> Bruce Easterbrook P.Eng.
> Abode Engineering
>
> On 22/08/2013 2:54 PM, Eric O'Neill wrote:
>
> Bruce and Matthew,
>
> My understanding of defining the vertices is that the way they
> line up only affects how the wall constructions are defined, and
> shouldn't result in an error. For instance, for zone boundaries
> defined near an exterior wall where the vertices don't line up
> exactly, eQUEST may define them as an interior wall, or possibly
> an exterior wall with no windows (I haven't taken the time to
> discern what the ruleset is for that). Internal zones that don't
> line up perfectly are usually defined as adiabatic rather than as
> an interior wall construction, but the space and zones themselves
> don't really care if they line up or even overlap. For my
> purposes, I took the time to do the exterior walls correctly, but
> it's not worth the additional time to get the interior walls
> perfect (this isn't for LEED or anything quite to that level of
> detail) for every single space.
>
> As an example, you can set up and run a brief model on a building
> like below, and it will fully simulate without errors, despite
> obvious overlapping floorspaces and walls that don't line up.
>
> Normally I take the time to line things up well, so I could be
> wrong on this. Am I misunderstanding what you guys are trying to
> say, or (more importantly) am I missing something wrong with this
> approach?
>
> I tried Robby's suggestion - I duplicated that shell, and on one
> copy I deleted the north zones, and the other I deleted the south
> zones, and the errors have disappeared.
>
> Thanks everyone!
>
> Eric L. O'Neill, P.E., LEED AP
> Direct 608.785.3328 |Michaels Energy
>
> *From:*Bruce Easterbrook [mailto:bruce5 at bellnet.ca]
> *Sent:* Thursday, August 22, 2013 11:50 AM
> *To:* Eric O'Neill
> *Cc:* equest-users at lists.onebuilding.org
> <mailto:equest-users at lists.onebuilding.org>
> *Subject:* Re: [Equest-users] Expression Evaluation Error
>
> I would say some of your vertices are not lining up. Even
> visually I can see a few potential problem points for you. They
> have to be exact. Nothing can overlap nor can there be any gaps.
> eQuest is very picky, you pretty much have to be exact to 3
> decimal places. It may sound like a lot of work but I would print
> out your CAD plan and mark your points on it. When I do my
> perimeter I add extra points on the exterior walls where the zones
> intersect. It gives you something to snap to when you are
> defining your zones later. When defining your zone polygons you
> can also directly edit the number if you can't get the point to
> snap exactly. The only snap I use is the CAD drawing. One other
> thing I do is make an eQuest layer on the CAD drawing and simplify
> the plan to the perimeter and the zones. It makes it easier in
> the long run to keep track of all the vertices. There are too
> many potential places to snap to on an architectural drawing.
> Bruce Easterbrook P.Eng
> Abode Engineering
>
> On 22/08/2013 11:55 AM, Eric O'Neill wrote:
>
> This one has me stumped, and it looks like it's been an issue
> before, so I'm hoping someone has an idea. I was building a
> model in the wizard and went to save-as before something got
> screwy, and it appeared I was too late. I got an error for
> multiple zones that read "MULTIPLIER in /XXXzone/ has
> Expression Evaluation Error: Invalid BDL reference", followed
> up by a bunch of zone errors stating that they were
> "referenced but not defined". I did some searching and came up
> with a few hits, but no solutions (that I could see). I bit
> the bullet and went back and tried to rezone it from my last
> save, and while the error seems to occur for different zones,
> I still got it. I went through and tried to purge out some
> AHU's and spaces that may have pushed me up against some limit
> I'm not aware of, but nothing's helped so far.
>
> Below is what I'm currently zoning, and you can see that in
> the building footprint screen, there are zones that I've
> defined that aren't showing up. I'm attaching the pd2. Any
> thoughts or ideas would be appreciated!
>
> Eric L. O'Neill, P.E., LEED AP
> Managing Engineer - Implementation | Michaels Energy
> Phone 608.785.3328 | Cell 608.792.7721
> www.michaelsenergy.com
> <http://www.michaelsenergy.com><http://facebook.com/MichaelsEnergy><http://www.linkedin.com/company/michaels-energy><http://www.youtube.com/user/MichaelsEnergy><http://twitter.com/MichaelsEnergy>
>
>
>
>
>
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