[Virtual-sim] [Bldg-sim] IES-VE Energy

Thu Feb 26 09:05:06 PST 2009

Karen and all,

I'm confused here....how can a program that takes up to 3 hours to rename
the zones but then takes minutes to get results, be better than something
that takes a few minutes to rename, but then takes a couple of hours to run?
They are about the same surely?  The only advantage I can see is that
further iteration might be quicker in the former assuming your geometry
doesn't change.

I have been using various modelling tools such as IES VE, TAS and
DesignBuilder as well as a few other tools when necessary (Fluent & CHAM CFD
etc) since the late 90s.   IES is good, it's quick to produce models and
excellent for dynamic natural ventilation design.  TAS is better at the HVAC
and natural ventilation design aspects than IES and I think it's more
accurate, but it's front end still lacks some of the functionality of other
tools.  Hopefully that is being addressed by their links with Bentley.  My
colleague, Chris Yates (also on this list) has become a bit of a wiz with
the sketchup plug in for IES and this appears to be much better than relying
on the gbxml output of revit.  

DesignBuilder is the tool that I use most now in both SBEM (UK regulations
format) and EnergyPlus for dynamic modelling.  It takes a lot of the best
features of both IES and TAS and then adds some other nice touches in terms
of data application to speed up the process of setting up your models.  The
only sticking point with it is that EnergyPlus is painfully slow.  The main
thing I'd like is for that to be changed and improved.  Carrying out
simulations with all the lighting controls and calculated natural
ventilation turned on for buildings with over 100 zones is nigh on
impossible as I don't fancy leaving it running for a week or two.  I have to
carry out major sub-division of models or calculate individual zones then
schedule up the vent based on those results or just go with scheduled vent.
Thankfully the reporting methodology from DesignBuilder is pretty good,
though I have to admit I quite like some of the report wizard output by
equest.

The main advantage of the commercial tools as opposed to the free tools such
as DOE and equest, is that they use an interactive 3d model to input the
building and that you can interrogate much more easily for post-processing.
This means you gain an understanding of the building form much more easily
and many link with other tools for further analysis.  I like some of what
equest has to offer, but I much prefer the interactive model building tools
that IES, TAS and DeisgnBuilder offer.  They just make it...easier...and
generally quicker and more efficient when you consider the other studies
that you can do (e.g daylighting, CFD, etc).

In terms of asking for changes -  having worked for IES (and with many other
developers), the stock answer even to their own team was...yes it's on the
list.   My guess is that will still be the same.

Regards

Paul

Dr Paul Carey

Director

Low Carbon Energy Assessor

Zero Energy Design Ltd

10A Portland Place

2-22 Mottram Road

Stalybridge

SK15 3AD

T:  0161 3386200

F:  0161 3031281

M: 0789 4098012

E:  paul at zed-uk.com

W:  www.zed-uk.com

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen Walkerman
Sent: 25 February 2009 23:06
To: Varkie C Thomas
Cc: Varkie Thomas; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] IES-VE Energy

Varkie,

I disagree with your statement that eQuest is not appropriate for large
buildings because you can't change space names to match architectural names
in wizard mode, and the inputs created from the wizard aren't appropriate
for all spaces.  The wizards are called "Schematic Design Wizard" and
"Design Development Wizard" for a reason.  They aren't desinged for detail,
they're designed to help you make big design decisions quickly.  If you want
the building to be modeled as closely as possible to the final design, this
takes some extra work.  Yeah, re-naming spaces is a pain, but at 5 seconds
per space, re-naming 1,000 spaces takes about 1.5 hours, well worth the
effort.  If you re-name zones too, maybe it's 3 hours total.

Yeah, some things about eQuest are clumsy, like why does it create one
underground wall (and floor) consturction for each surface, when only 4-5
are needed for the whole model?  Why does it re-create occupancy, lighting
and micellaneous equipment schedules for each shell, even if the use is the
same?  And why does it create tons of duplicate infiltration schedules?
BUT... this takes an hour or two to clean up, and then you have a decently
flexible model that gives you reasonable results in a matter of minutes.
Versus a program that takes 1-2 hours to run.  I've done a few LEED projects
in Trace700 and it's painful modeling a design case and four (rotated) base
cases at 1-2 hours each, especially if you then find you've left anything
out.

I definitely agree that there are some major things missing in all modeling
programs, which is why I'm putting together a "Master Wish List" of
modeler's desires.  If you have things that you would like to be able to
model, things you'd like to be able to model more easily, or things that you
can do that you feel are very important, please send me your list.  I
currently have contact info for about 10 people representing various
simulation programs who want to know what we want!  Now's our chance to have
some input!

--
Karen

On Wed, Feb 25, 2009 at 2:15 PM, Varkie C Thomas <thomasv at iit.edu> wrote:

Graham,

The comment below stands out which might also be the reason for not using
EnergyPlus on large projects.

- DOE-2.2 runs much quicker.  For comparable 30,000 m2 buildings I would say
DOE-2 runs in 1 minute and IES VE with an APhvac network probably 1-2 hours.
If you through in Macroflo it probably adds another hour of simulation time.
As a result iterative trial and error debugging has to be done on a 1-2 week
period.

Large building projects (1 to 10 million sqft) with up to 1,000 zones and 70
systems ranging in size from 10,000 to 200,000 cfm (pardon the English units
- the USA & the Bahamas are not going to switch to metric) require several
iterative runs to get the input errors fixed.  Breaking up the project into
small pieces is not a solution since it affects demand costs, central plants
and other components.  I have worked on such projects using DOE2.1E and
TRACE600/700.  

eQUEST is not suitable for such projects either.  One of its limitations is
that you cannot enter the space names shown on architectural drawings.
Others include assuming all the input data and making all the decisions for
you when you enter the type of building.  1000 zones means 1000 infiltration
schedules and multiples of other building components. It is unrealistic to
check all the input created by eQUEST for errors. Fixing everything to match
the exact project data has to be done in detailed edit.  Detailed edit means
you lose access to the graphical method of creating the building model from
AutoCAD drawings which is the main benefit of this program.

Varkie

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