[Equest-users] App G Baseline CHW Pump Power
James Hansen
JHANSEN at ghtltd.com
Wed Nov 27 10:06:00 PST 2013
Nobody is gaming the system Tim. I'm working on a couple LEED v4 pilot projects, and the spreadsheet for the Minimum Energy Performance credits still lists 22 W / gpm for both systems (and it is a REVISED spreadsheet in a totally different format, not something that was copy/pasted from the v3 spreadsheet).
I can send it to you offline if you don't have access to the new templates.
For reference, my last primary / secondary chilled water job had a condenser water pump needing 50 feet of head, a primary chilled water pump needing 58 feet of head, and a secondary chilled water pump needing 65 feet of head. This would fall exactly in line with the 19 W / gpm allowance for condenser water, and 22 W / gpm for each of the chilled water pumps. Perhaps GBCI had an internal ruling based on the hundreds of chilled water plant projects they see each year??
GHT Limited
James Hansen, PE, LEED AP, BEMP
Senior Associate
1110 N. Glebe Road, Suite 300
Arlington, VA 22201
703.243.1200 (main)
703.338.5754 (direct/cell)
www.ghtltd.com <http://www.ghtltd.com>
From: Howe, Timothy [mailto:Timothy.Howe at stantec.com]
Sent: Wednesday, November 27, 2013 12:56 PM
To: James Hansen; Nick Caton; Christian Kaltreider; Bishop, Bill; Joe Fleming; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] App G Baseline CHW Pump Power
James,
The ASHRAE interpretation came around or after the latest Table 1.4 template was released, both in December 2012. I think that it is fair to assume that the USGBC just missed the point on this one and despite that any good reviewer should push back on using 22 w/gpm on both pumps. The template supplied by the USGBC is a tool to document the model inputs and not what is used to stipulate how to model and follow the PRM.
The PRM is the only set of rules to which EAp2/EAc1 performance is developed with the only official deviation from what is contained within it is the DES guidance produced by the USGBC.
Gaming the performance of a model because of this misinterpretation by the USGBC is bad for the modeling community and should be avoided.
Tim.
Timothy Howe, MS, BEMP, LEED® AP
Mechanical Designer
Stantec
61 Commercial Street, Suite 100 Rochester NY 14614-1009
Phone: (585) 413-5347
Cell: (585) 281-3223
Fax: (585) 272-1814
timothy.howe at stantec.com <mailto:timothy.howe at stantec.com>
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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Wednesday, November 27, 2013 12:41 PM
To: Nick Caton; Christian Kaltreider; Bishop, Bill; Joe Fleming; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] App G Baseline CHW Pump Power
For what it's worth, I've used 22 W / gpm for each system (primary and secondary) for the past few LEED projects, and have not had any comments, given that the LEED "Revised Section 1 4 Table" from Dec 2012 specifically lists that the primary and secondary pumping system should be at 22 W / gpm. By the way, if you're not using the Table 1.4 excel spreadsheet to document EAp2/EAc1, you should, because it makes it way easier for GBCI to review your model, and it minimizes the chance and/or severity of comments.
CHW Loop Configuration
Primary/secondary per G3.1.3.10
N/A
N/A
Number of Primary CHW Pumps
1 per chiller per G3.1.3.11
N/A
#
N/A
#
Primary CHW Pump Power
22 W/gpm per G3.1.3.10
N/A
N/A
W/gpm
Primary CHW Pump Flow
Auto-sized with a capacity ratio of 1.0 based on CHW temperatures
N/A
gpm
N/A
gpm
Primary CHW Pump Control
Constant Flow - each primary pump interlocked to operate with associated chiller - G3.1.3.10, G3.1.3.11
N/A
N/A
Number of Secondary CHW Pumps
1 per G3.1.3.10
N/A
#
N/A
#
Secondary CHW Pump Power
22 W/gpm per G3.1.3.10
N/A
W/gpm
N/A
W/gpm
Secondary CHW Pump Flow
Auto-sized with a capacity ratio of 1.0 based on CHW temperatures
N/A
gpm
N/A
gpm
Secondary CHW Pump Control
<300 tons: riding the pump curve
≥300 tons: variable speed
N/A
N/A
Regardless of how ASHRAE has ruled, GBCI makes it pretty clear that you should use 22 W / gpm for both primary and secondary loop pumps.
GHT Limited
James Hansen, PE, LEED AP, BEMP
Senior Associate
1110 N. Glebe Road, Suite 300
Arlington, VA 22201
703.243.1200 (main)
703.338.5754 (direct/cell)
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 Nick Caton
Sent: Wednesday, November 27, 2013 12:32 PM
To: Christian Kaltreider; 'Bishop, Bill'; 'Joe Fleming'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] App G Baseline CHW Pump Power
Thanks for bringing that back up - I thought this remained an ambiguous/grey area indefinitely.
As to potential for squeezing extra performance via power distribution between pumps… I’ve never considered that, but to share my anecdotal experience I typically just dump all the power on the secondary pumps and make the primary pumps “powerless” for simplicity’s sake in documentation/QC. I suppose for variable-secondary cases that approach might miss out on some baseline energy that would otherwise be burned by a CV primary…
A “logical” approach would be to proportion the ‘system’ 22W/GPM by a ratio to match the pump sizing in the actual design.
That said, I’ve never been told to proportion my pump energies any differently than my simplified approach of dumping it all in one place.
Hope that helps =),
~Nick
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Christian Kaltreider
Sent: Monday, November 25, 2013 2:26 PM
To: 'Bishop, Bill'; 'Joe Fleming'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] App G Baseline CHW Pump Power
Yes, that lays it out pretty clearly. 22 W/GPM system total.
I wonder if future 90.1 versions will prevent gaming of the system (intentional or not) by offering guidance on power allocation among pumps?
Thanks for the helpful replies,
Christian
From: Bishop, Bill [mailto:bbishop at pathfinder-ea.com]
Sent: Monday, November 25, 2013 2:11 PM
To: Joe Fleming; 'Christian Kaltreider'; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] App G Baseline CHW Pump Power
Christian,
Confirming what Joe says, an ASHRAE interpretation <https://www.ashrae.org/File%20Library/docLib/StdsInterpretations/IC-90-1-2007-14.pdf> clarified that 22W/gpm is the total power of all baseline CHW pumps.
Regards,
Bill
William Bishop, PE, BEMP, BEAP, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 325-6004 Ext. 114 F: (585) 325-6005
bbishop at pathfinder-ea.com <mailto:wbishop at pathfinder-ea.com> www.pathfinder-ea.com <http://www.pathfinder-ea.com/>
P Sustainability – the forest AND the trees. P
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Joe Fleming
Sent: Monday, November 25, 2013 2:07 PM
To: 'Christian Kaltreider'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] App G Baseline CHW Pump Power
Almost certain that the GBCI interprets it as a whole system divvy, not each pump with 22W/GPM.
Regards
Joe Fleming | PE, LEED AP BD+C, BEMP
Commissioning Agent / Energy Modeler | The Spinnaker Group
561.602.3132 | joe at thespinnakergroupinc.com
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Christian Kaltreider
Sent: Monday, November 25, 2013 2:01 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] App G Baseline CHW Pump Power
Hello,
In November 2010, around the same time someone was modeling a building that looked like a turkey, there was a conversation on this list about baseline CHW pump power:
http://lists.onebuilding.org/htdig.cgi/equest-users-onebuilding.org/2010-November/006941.html
Part of the discussion was some back and forth about how to apply G 3.1.3.10. This section calls for baseline pump power to equal 22W/GPM and for the CHW pumping configuration to be primary/secondary. Some had the opinion that each pump (primary and secondary loops) should have 22 W/GPM assigned to it, while others thought that the total CHW pump system power should sum to 22 W/GPM, and that it was up to the modeler to divvy up the power among pumps as they see fit. I did not see a clear conclusion.
Does anyone know if a general consensus was reached?
Thanks,
Christian
Christian Kaltreider, LEED AP | Energy Analyst
Sud Associates, P.A. | T 828.255.4691 | F 828.255.4949 | www.sudassociates.com
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