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

[Matthew W. Higgins]

Bill found some issues in the PS-H with this methodology (Thanks Bill!). I'm going to look at it again and may be able to provide some more feedback. I should have noted that the availability schedules don't get around your problem, they just allow for that equipment to be on the loop and unused/sparingly-used.

MATTHEW HIGGINS
CEM, ASHRAE-HBDP, LEED-AP (BD+C)

Bridgers & Paxton Consulting Engineers, Inc.
4600-C Montgomery Blvd. NE
Albuquerque, NM  87109

505.883.4111  (t)    505.888.1436  (f)



From: Matthew W. Higgins
Sent: Thursday, August 15, 2013 4:10 PM
To: 'Kathryn Kerns'; Steve Woolery; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] LEED Issue with EQuest Software's Ability to Model Boilers on Ground Loops

Hi I recently went thru this too.

If you go through the usual steps to create a GCHP loop, do these steps next:


-          Create a hot water loop (and leave it as primary)

-          Go back to the GCHP loop and call it secondary

-          After doing so close out of that loop and go back into it and indicate that the primary loop is the HW loop

-          Create a boiler and put it on the HW loop

-          After this you have 2 options:

1)      Use equipment controls/load management and flag schedules to allow one loop to be on and the other off seasonally as you see necessary

2)      Create an availability schedule in the loop's control tab for the HW loop to suggest a high degree of diversity or off seasonally as mentioned

I prefer step 2 above and I know there are some issues when you don't have a tower, like below, but I've made it work previously.

[cid:image001.jpg at 01CE9A66.DA2591C0]

MATTHEW HIGGINS
CEM, ASHRAE-HBDP, LEED-AP (BD+C)

Bridgers & Paxton Consulting Engineers, Inc.
4600-C Montgomery Blvd. NE
Albuquerque, NM  87109

505.883.4111  (t)    505.888.1436  (f)




From: equest-users-bounces at lists.onebuilding.org<mailto: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 10:27 AM
To: Steve Woolery; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] LEED Issue with EQuest Software's Ability to Model Boilers 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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