[Equest-users] Revert efficiencies to autosize from detailed?

[Laura Howe, RCE]

The modeler used heat pump for heating and cooling.  The exact comment is
long (too long for me to type, about 1/3 of a page), but it does talk to
using proper efficiency based on Equest autosizing (which as far as I can
tell autosizing was used, however there may be issues with the internal
loads used, that's another thing to investigate).  I'm not sure how the
dummy project example you give will work, without fully building the
facility and loads in a model, autosizing isn't going to really work since
the required efficiency is based on system capacity?  I'm thinking I will
work with the apparent system sizing I have now, update the efficiency
based on 90.1, rerun and hope the sizing stays within the same category.
Iterate if necessary.  

 

The comment also brought up the need to break out fan energy from
cooling/heating energy, which I guess I had hoped would be worked out with
reverting to default.  In response to Nathan's comments, I will review this
topic in the latest forums (this one and bldg-sim being the only two I use,
any others pertinent?) and hopefully get it straightened out.

 

On the flip side, a non-mandatory point is that they also seemed to use too
high of an efficiency for cooling.  Perhaps that will cancel out the low
heating efficiency in the end..

 

Thanks so much, anything else is appreciated.  I'm sure I'll be back once
I'm fully confused with splitting as Nathan talked about.

 

From: Patrick J. O'Leary, Jr. [mailto:poleary1969 at gmail.com] 
Sent: Tuesday, June 12, 2012 1:40 PM
To: Laura Howe, RCE
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Revert efficiencies to autosize from detailed?

 

short answer: no

longer answer:  equest reverts to a default efficiency of the type of unit
selected, in eir/hir not seer/eer or hspf/cop, that is not based on
90.1-2004, 2007, or 2010.  the 'easiest' method of determing a 'correct'
efficiency (search archives for different methods of calculating a 'correct'
efficiency') is to simply open a dummy project, go to the hvac systems,
change the efficiency (in seer or eer as applies to the minimum required for
your unit type) to the 90.1 required, save the project, then switch it to
detailed mode & look at the hvac unit efficiency in eir/hir.

out of curiosity, what was the exact comment & what did the modeler use for
what system types?

On 6/12/12 2:11 PM, Laura Howe, RCE wrote: 

HI All-

 

While there are some posts similar to this issue, I want to ask the group
for clarification for a slightly different application.  Please bear with me
for some assistance, I'd sure appreciate it!

 

I am working on someone else's model that has had comments back from GBCI
for a LEED project. The model came to me in detailed mode.  They note that
in the baseline model apparently non-90.1 baseline efficiencies were used.
Looking at the model, it does seem that the modeler manually entered
efficiencies (they are in red) and they do not seem to be correct (even the
GBCI comment notes this).  They are less efficient than 90.1. In some of the
similar threads on this topic, someone mentioned that you can revert to
autosizing by right clicking on the heating and cooling capacity and
selecting "restore default".  Since the modeler did not manually input
system size, just system efficiency (both cooling and heating hp eff, fan
design kw/cfm and total eff frac seem to be manually entered), my question
is if I restore those efficiency values to default (using right clicking),
will Equest use the proper efficiencies and I'm good to ho?  I've done this,
and it seems to work, although I'm not experienced enough to truly verify
this.  

 

When I compare the two models (original base and my reverted base) I do see
where the power demand has dropped (SV-A), and none of the peak loads have
changed (LS-A) but the equipment sizing (SV-A) has increased.  This all
seems correct, do others think I am on track here?  Using the correct
methodology?

 

If I can also confirm another question, LEED specific.  I understand 90.1 is
the only appropriate base case for LEED even in Washington state, even if
portions of their energy code are more stringent, correct?  The requirement
to achieve a 10% reduction is how I think LEED addresses more stringent
state codes so the base doesn't need to be written specific to those
(numerous) state codes.  Correct? One comment from the client leads me to
think that complying with WA code might explain the difference in equipment
efficiencies used in the base case, and even though it doesn't add up I want
to confirm my understanding.

 

Another issue that further confuses this is that the modeler apparently
chose two of the systems to be variable speed (all are system type 4,
constant volume in 90.1) and I'm not sure why.  The original modeler is not
available for questioning.  Any ideas?  The VFD's were applied to an office
space and data/server room packaged heat pumps, but not a large storage
space.  Based on what I know right now, it seems those should be modeled
constant volume.  If I'm updating the base model, I think it makes sense to
correct this if the base incorrectly models a more efficient system.

 

Lastly, can anyone tell me how to change the project descriptor at the top
left of the sim reports?  It's got some boilerplate name and it sure would
be nice to have the filename show, or at least a single descriptor I can
update in each model run.

 

Thanks so much-

Laura






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