[Equest-users] LEED Issue with EQuest Software's Ability to ModelBoilers on Ground Loops

[Kathryn Kerns]

Unless you have a trick I don't know, no you can't, not without creating a fatal error that says "cannot combine a boiler with a ground loop HX" and having the program not run. Please, if you have a successfully running model with a ground loop HX and a boiler on the same Water Loop HP, please send me the input file.

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From: James Hansen [mailto:JHANSEN at ghtltd.com]
Sent: Thu 8/15/2013 9:35 AM
To: Kathryn Kerns; Steve Woolery; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] LEED Issue with EQuest Software's Ability to ModelBoilers on Ground Loops



You can absolutely add a boiler to a GSHP loop.  Just add a boiler, and when asked which HW loop to assign it to, you can pick the GSHP Loop (as long as that loop is a "Water Loop HP" loop).

 

I think more than likely this is the reason you are getting the comments you are.  This reviewer may know that you CAN add a boiler to a GSHP loop, which is the reason for comment #4.

 

I doubt GBCI is trying to eliminate eQuest as a modeling option.

 

Also, printing out hourly reports from an eQuest run is often helpful in proving your case (whatever case that may be).  If you can show, via hourly reports, that the heat picked up by the GSHP heat exchanger exceeds the heating load for all 8,760 hours of the day, then case closed...that's all you need to submit.

 

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)

703-338-5754 (cell)
703-276-1376 (fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Kathryn Kerns
Sent: Thursday, August 15, 2013 12:27 PM
To: Steve Woolery; equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Issue with EQuest Software's Ability to ModelBoilers on Ground Loops

 

Everyone, I have received a snarky comment from the LEED reviewers regarding eQuest and not being able to model back-up boilers on a ground heat pump loop. See below. The ground loop is large enough not to generate any temperature low alarm messages, the ground loop pump flow never reaches 100% flow except for 1 hour and the ground loop heating capacity is never exceeded. These facts do not appear to be a good enough explanation not modeling the back up gas boiler. 

 

My questions for the group are:

1. Is there a way to add a boiler or some additional heat source to a ground loop in eQuest?  As far as I know the only work around I have discovered is to represent the ground loop by creating a water loop and adding a magical no energy consuming boiler and fluid cooler to a heat pump water loop and change the water loop parameters to match ground loop parameters. Then you can add normal boilers that will start if the non-energy consuming ground loop boiler is too small for the building heat load.  I offered this option to the LEED reviewer and they replied that it was not an established work around.

 

2. If there is no way to attach a boiler to a ground loop in eQuest, is there some established work around that somebody has used that was accepted by a LEED reviewer?

 

3. Is there anything in the reports that lists the maximum and minimum ground loop temperatures? I have been unable to locate it. 

 

4. Does anyone have an written explanation to answer "If this [the boiler] is not being modeled in the energy modeling software then provide a thorough explanation for why it cannot be modeled. "?

 

5. Does this sound like LEED is trying to eliminate eQuest software, and if so, is there anything we can do about it? "in the future the software selected to simulate the building components must be able to model those components "

 

The project team could possibly demonstrate that the boiler would not operate through a series of engineering calculations, some other software that could possibly simulate the building's loop temperatures, or through a thorough explanation of how the system operation prevents the boiler from operating. In short the project team must demonstrate that the boiler will not operate, not just say that is the case without presenting some evidence. If this is not being modeled in the energy modeling software then provide a thorough explanation for why it cannot be modeled. In the future the software selected to simulate the building components must be able to model those components or use an exceptional calculation (work around) to do so (G2.2). 

 

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