My company has used Trace for many years with the main purpose to
calculate loads. Trace has continued to evolve. However, with the
evolution the program has become more and more detailed for input.
Additionally, the time it takes to calculate results alone can be
extremely lengthy (5+ hours with full year weather data). Now that the
need for energy modeling especially for LEED has dramatically increased,
I am currently modeling several projects using Trace. In talking with a
few architects and even a third party energy modeler, they are using
eQuest.
I realize there is a learning curve for energy modeling as well as new
software. However, my company is looking for an energy modeling program
that allows for straight forward input and reliable/accurate results.
I have downloaded eQuest and spent a few hours looking at the program
and capabilities. At first glance eQuest appears to not be as detailed
in its inputs.
Does anyone have any experience with Trace and eQuest? Pros vs Cons for
energy modeling?
Thanks in advance,
Sherie Hensley P.E., LEED AP
Sherie,
Take a look at the DOE2 docuementation PDF's to get a real feel for the
input capabilities of eQuest. eQuest is, fundamentally, a "training
wheels GUI" for DOE2. IMHO eQuest/DOE2 provides greater modeling
options than Trace 700, but the learning curve is "inversely
proportional to the cube of your overall computing systems expertise"
;-)
We're a 100 plus person MEP firm, and to master (well, begin mastering)
eQuest/DOE2 we essentially dedicated an experienced engineer/computer
guy to do energy studies for a year. Several junior engineers rotate
as-needed to help out, since as it stands right now there's a fair
amount of technical front-end work to do for every project in first
defining the envelope before proceeding engineering modeling.
Same with Trace, but my issue with Trace is that it lacks visual
feedback as to what the model looks like -- I don't (and who really
does) have time to backcheck a pile of output text reports defining the
building envelope. eQuest provides a crude but effective 3D color-coded
graphic that provides a quick backchck of model features -- essentially
immediate feedback on missing walls, windows, roofs etc.
Am looking forward to the day when drawing data can be read directly by
eQuest or EnergyPlus (E+ has a long-promised SketchUp module in the
works), but it hasn't yet arrived. We hear that IES can do it for Revit
projects, but we jost don't have any Revit projects in the queue right
now.
HTH...
Brandon Nichols, PE, LEED(r) AP
Sherie and all,
Where I work, we also have been using Trace for decades. I've used
Trace, HAP, and eQuest. for years now. Here is my take:
eQuest:
* Great for quick energy models where room-by-room breakdown of
loads and energy use is not required.
* Not very useful for load calculations. This is what the eQuest
training class taught me. Something about peak load calculations
not appropriate (weather data?). I wish they could fix that. I'd
be tempted to use eQuest for load calculations.
* Determine energy impact of improvement measures quickly.
* Energy use reports are pretty and impress everyone.
* Like Brandon said, the 3D views of the building geometry is useful
for checking.
* Support is best gotten from this mailing list. Sometimes
questions go unanswered.
* The two wizards to get your model mostly done.
* Free!
Trace:
* Proven and reliable for loads AND energy study work.
* Able to do more detailed zone and room breakdown of load components.
* Output reports seem to be tailored specifically for load
calculation and work well for that purpose.
* Energy and load output reports are not pretty, but the experienced
users like them.
* The professional support technicians at Trane are excellent and
you can get answers fast.
* Must start your model from scratch every time (although we hear
they are working on a wizard)
* Costs a lot of $$$
When we do HVAC design work in conjunction with energy study work, the
Project Engineer always wants to use Trace for the energy model. He
will say that because he already has a Trace model and all we need to do
is add schedules and energy rates. It has been my experience that when
you have a building model detailed enough for load calculations, it is
WAY too detailed for energy modeling. The Trace energy calculations
take too long and are not really more accurate.
5 hours for results on energy modeling is outrageous. Sounds like a
loads model is being used for energy modeling. Time to re-think. Even
my large eQuest models only take a few minutes to simulate.
Randall C. Wilkinson , P.E., C.E.M., LEED A.P.
To improve on eQUEST loads calculations, you can always choose a design day in Detailed Data Edit mode. Make sure your CDD and HDD schedule values are what you would want them to be on a heating/cooling design day, and specify a design day in the "Project & Site" area. You do this by right-clicking on "Project:," which appears on the top of the list at the left of your screen, directly above a folder called "Global Parameters." Then you choose "Create Design Day" and go from there. When you run the simulation, equipment should be sized based on the loads calculated on this design day. In your .sim file, most/all of the loads reports have "standard" and "design day" pages so that you can compare. In my experience, sometimes the 99%/1% DD conditions produce smaller loads than the annual simulation, so you'll want to pay attention to that.
Kristin M. Field, EI
Sherie and all,
Where I work, we also have been using Trace for decades. I've used Trace, HAP, and eQuest. for years now. Here is my take:
eQuest:
Great for quick energy models where room-by-room breakdown of loads and energy use is not required.
Not very useful for load calculations. This is what the eQuest training class taught me. Something about peak load calculations not appropriate (weather data?). I wish they could fix that. I'd be tempted to use eQuest for load calculations.
Determine energy impact of improvement measures quickly.
Energy use reports are pretty and impress everyone.
Like Brandon said, the 3D views of the building geometry is useful for checking.
Support is best gotten from this mailing list. Sometimes questions go unanswered.
The two wizards to get your model mostly done.
Free!
Trace:
Proven and reliable for loads AND energy study work.
Able to do more detailed zone and room breakdown of load components.
Output reports seem to be tailored specifically for load calculation and work well for that purpose.
Energy and load output reports are not pretty, but the experienced users like them.
The professional support technicians at Trane are excellent and you can get answers fast.
Must start your model from scratch every time (although we hear they are working on a wizard)
Costs a lot of $$$
When we do HVAC design work in conjunction with energy study work, the Project Engineer always wants to use Trace for the energy model. He will say that because he already has a Trace model and all we need to do is add schedules and energy rates. It has been my experience that when you have a building model detailed enough for load calculations, it is WAY too detailed for energy modeling. The Trace energy calculations take too long and are not really more accurate.
5 hours for results on energy modeling is outrageous. Sounds like a loads model is being used for energy modeling. Time to re-think. Even my large eQuest models only take a few minutes to simulate.
Randy
--
Randall C. Wilkinson , P.E., C.E.M., LEED A.P.
Sherie E. Hensley wrote:
My company has used Trace for many years with the main purpose to calculate loads. Trace has continued to evolve. However, with the evolution the program has become more and more detailed for input. Additionally, the time it takes to calculate results alone can be extremely lengthy (5+ hours with full year weather data). Now that the need for energy modeling especially for LEED has dramatically increased, I am currently modeling several projects using Trace. In talking with a few architects and even a third party energy modeler, they are using eQuest.
I realize there is a learning curve for energy modeling as well as new software. However, my company is looking for an energy modeling program that allows for straight forward input and reliable/accurate results.
I have downloaded eQuest and spent a few hours looking at the program and capabilities. At first glance eQuest appears to not be as detailed in its inputs.
Does anyone have any experience with Trace and eQuest? Pros vs Cons for energy modeling?
Thanks in advance,
Sherie Hensley P.E., LEED AP
As a former Trace user and an aspiring eQuest user, I would echo Randy's
insight. The paid technical support is fantastic with Trace. I would
send emails to CDSHelp and usually get a response within an hour. While
not perfect, the Trace program is comprehensive and actively updated.
With the new Trace Wizard tool, one can building simple models very fast
(although in order to access this functionality, the initial dialog box
must be closed and the File, New and then select the Wizard ... this is
not intuitive). I also have found great use for the Chiller Plant
Analysis tool that allows me to focus on the central plant if I already
have loads.
I suspect that the price of eQuest is a big reason many architects are
"using" eQuest. My experience with energy modeling is that it really
takes detailed inputs to get it right. I typically work on existing
buildings so I need to calibrate with the energy bills. I try to break
the model down by control zones (i.e. if a controller operates the HVAC
system on 3 rooms then those become one zone and the level of detail I
go to from an architectural standpoint. Sometimes this requires room by
room analysis and sometimes I can aggregate these control zones together
if the control and exposures are identical). This often requires a lot
of paper and highlighters to accomplish well.
Having said that, if I want to decide on system X versus system Y, I can
use the Wizard function of Trace to develop a block building, pull in a
sample utility rate, and determine my systems and total energy use
really quickly. It is not 8760 but gets me similar results to a quick
eQuest run. I do like the 3D building model that eQuest develops as a
visual check of the envelope input. It is really useful.
In the end, the experience of the user with the tool is more important
than which tool is actually used. Over time one learns the work arounds
of the limitations of all tools or uses a different tool for different
modeling scenarios.
I would suggest trying the Wizard. Learning eQuest in your spare time
and asking the architects to send you the file of the building so that
you can import it from AutoCAD into Trace. Building modeling is a bit of
a slog but once the basic model is built (keeping the end goal of energy
analysis in mind through effective zoning or grouping of systems and
control points), the resultant alternatives can be developed rather
quickly.
I am not sure how large of a system you have that takes 5 hours to run.
I have run a 250,000 square foot high school with 14 VAV systems, 6 H&V
systems, a central plant on 8760 and the run is around 15 minutes (maybe
its time to ask your boss to upgrade that old 386).
Kevin
As a post script, I have found Trace to run rather/very quickly as well - even for large buildings with complex systems as Kevin indicates below.
I think the key is to make sure you are maximizing the use of Trace's templates.
Trace's use of templates is a very nice feature and seems to be a potential benefit over Equest (although, I'm just a beginning Equest user).
Each energy modeling program seems to have its own pros and cons, though, with no one program being all things to all people on all projects.
Julia
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