[Equest-users] VRV System Modeling

[Gary.Schrader at tac.com]

Dave,
 
I have heard the rumors about a VRV system being added to DOE 2.2 in the
future as well. The last time I heard the rumor, the package was
supposed to be out this spring. As is true of the entire software
industry, that likely means it will appear sometime in the year 2012.
(Predicted release date + 3 years = Actual release date)
 
I hope there is someone on here who can better clarify the date and
progress of the package...
 
To your second point, our office has been modeling Daikin VRV systems in
eQuest for a few months now. Don't get too excited... we haven't
actually installed one yet so we have no real data with which to prove
that we are modeling the systems correctly. That said, we also have only
modeled their "Heat-Pump" line and not their "Energy Recovery" line,
which allows simultaneous heating and cooling between zones.
 
We created custom curves with which to model the compressor by taking
Daikin Engineering data out of Daikin tables and plugging it into
eQuest. Then we model the system using the "Packaged Single Zone" system
type. We set the Indoor fan to two-speed and gave it a very light static
pressure, due to the fact that the system has multiple indoor fans with
low static vs. one fan with lots of static. We hard-keyed the CFMs, the
rated capacities, the compressor RPMs, low and high, the minimum cycling
part load ratio, the cooling (and heating) EIR, and set the compressor
to variable speed type and gave it a minimum unload ratio, again, all
from Daikin literature. We used eQuest's default low-speed EIR curve.
The capacity curve and the EIR curves we custom-created using eQuest and
Daikin data.
 
The results seem logical. Again, it's hard to prove that things are
dead-on because we have no real building to compare our results to.
Hopefully, though, that will give you a place to start.
 
I am not confident that I am modeling defrost correctly, and winter
results in general seem more sketchy. I am using eQuest's default
defrost running time fraction, which I assume is more pertinent to
standard unitary equipment. Daikin's defrost seems more efficient. It
also doesn't help that Daikin doesn't use either resistive or reverse
cycle for their defrost strategy... it's actually hot-gas bypass.
 
One last thing, all of the engineering data that we obtained from Daikin
was published on their website, www.daikinac.com.
 
I hope this helps. Good luck!

Gary Schrader
Engineer I

TAC
16011 College Blvd, Suite 212
Lenexa, KS  66219


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________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Dave
Hostetter
Sent: Monday, March 23, 2009 2:58 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] VRV System Modeling



Hello All,

 

I am working on a few projects which utilize Daikan VRV systems and I am
trying to model them using eQuest, without much luck.  I have talked
with a couple of different people, including some at Daikan and eQuest,
and have heard that as of right now the only full building energy
modeling program that supports VRV systems is EnergyPro.  I was also
told that an update to DOE2.2 and then eQuest which will address VRV
systems is in the works, but that these updates will most likely not be
out for a couple of months yet (maybe into next year).  I also have
heard that there have been some people who have been able to approximate
VRV systems within eQuest.

 

So my questions to all of you are: 

 

1).  What would be the best / most accurate approach to create a model
of a building with a VRV system?  Unfortunately I don't think that we
can wait a few months for the updates, so would it make most sense to
purchase EnergyPro or try to use a workaround method within eQuest?  Or
is there some third option that I am unaware of?

 

2).  Does anyone know how to approximate a VRV system within eQuest and
could explain it to me?  What kind of accuracy could I expect from this
method?

 

Any help would be much appreciated!

 

Thanks,

 

David P. Hostetter

EIT, LEED AP

Project Engineer

Integrated Holistic Design, LLC.

C: (717) 799-0599

 

2019C Miller Road

East Petersburg, PA  17520

 

 

 

 

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