[Equest-users] Again: eQUEST - serious trouble with LEED review

[Bishop, Bill]

Heinrich,
 
As Ravi Srinivasan suggested yesterday, don't oversize the chillers and
boilers. Use 0.50 for their capacity ratios. I believe the consensus in
the modeling community is to do the oversizing only at the system level,
adjusting the cool sizing ratio and heat sizing ratio (not the system
sizing ratio). It would not be surprising for the chillers and boilers
to spend a majority of the time at low part load, since they are
autosized based on total design loads and flowrates of all attached
equipment and processes. This is not a "problem" for the baseline.
 
Bill** 
________________________________

From: Heinrich.ib-bauklima.de [mailto:heinrich at ib-bauklima.de] 
Sent: Tuesday, January 25, 2011 5:41 AM
To: Bishop, Bill; equest-users at lists.onebuilding.org
Subject: Again: eQUEST - serious trouble with LEED review
 
Bill,
 
thank you for your advice.
I followed your instructions to change the model.
So I resolved the indicated reviewer comments.
Now there is no difference between secondary and primary chilled water
loop.
 
But now I have the dilemma that chillers and boilers of Baseline are
heavily oversized and are not sized to 115% and  125% respectively
according to demands of ASHRAE-90.1 App. G.
For checkup you can look at the Screenshots of the PS-C report, PV-A
report and the SS-D report that I have attached.
The part load of the chillers is about 40%-50% meaning a size 200%-250%
(see pump secondary CHW in PS-C report). 
The part load of the boilers is about 50%-60% meaning a size of
167%-200% (see pump HW in PS-C report).
 
So I still have a serious problem. Any help would heavily appreciated.
Can we solve this problem in eQUEST?
 
Heinrich
 
	 
	
________________________________

	Von: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
	Gesendet: Montag, 24. Januar 2011 19:49
	An: Heinrich.ib-bauklima.de; equest-users at lists.onebuilding.org
	Betreff: RE: [Equest-users] eQUEST - serios trouble with LEED
review
	Heinrich,
	 
	The chiller pumps requirement your reviewer is referring to is
in Section G3.1.3.11 (not G3.1.11). The model you sent currently has one
primary CHW pump attached to each of your two chillers, a separate
primary CHW pump on the primary loop, one secondary CHW pump and one
condenser water pump. You labeled your primary chiller pumps "Secondary
Pump CHW 1" and "Secondary Pump CHW 2", which is probably why the
reviewer thinks you only have one primary pump (the one on the primary
CHW loop labeled "Primary CHW Pump"). I suggest making the following
changes:
	*	Delete the separate pump attached to the primary CHW
loop 
	*	Relabel the chiller pumps to indicate they are primary
loop pumps 
	*	Add condenser water pumps for each chiller through the
"Loop Attachments" tab of the chillers; delete the other CW pump. 
	*	Change both the primary loop and secondary loop sizing
option to "secondary" to allow eQUEST to size based on coil loads. 
	*	Change the chiller capacity ratio for each chiller to
0.50. (Or use 0.575 if you want to oversize by 15% per G3.1.2.2 - I
don't know if this is supposed to apply to chillers.) Each chiller will
be sized for half the total load. 
	*	Allow the chiller capacity to default (remove the 0.9
MBtu/h). 
	*	Make sure you include both/all pages of the PS-C report
- your reviewer will then see that the secondary CHW pump is variable
flow. (Your zones have two-way valves already.) 
	*	The PV-A report will show that the total primary CHW
pump flow will nearly match the secondary CHW pump flow. 
	 
	Regards,
	Bill
	 
	William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers &
Architects LLP
	Mechanical Engineer
	 
	134 South Fitzhugh Street                             Rochester,
NY 14608
	T: (585) 325-6004 Ext. 114         F: (585) 325-6005
	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
Heinrich.ib-bauklima.de
	Sent: Monday, January 24, 2011 12:28 PM
	To: equest-users at lists.onebuilding.org
	Subject: [Equest-users] eQUEST - serios trouble with LEED review
	 
	Hi Everyone,
	 
	I got a review comment that got me in big trouble and I can't
find the solution yet.
	May be there is no solution for this in eQUEST....!
	I rate this forum as the very best address for difficulties with
eQUEST and LEED EAc1 simulation.
	So please give me some guidance and feel free to testthe model
attached.
	 
	Hereare the two comments of the reviewer.
	"It appears as if the pumps and circulation loops were not
modeled correctly for the Baseline Case. It appears based on the PS-C
reports that there is only one primary chilled water pump and one
condenser water pump for the Baseline Case. However, ASHRAE 90.1 Section
G3.1.11 requires that each chiller be modeled with separate condenser
water and chilled water pumps interlocked to operate with each
associated chiller. Please model two primary chilled water pumps and two
primary condenser water pumps in accordance with Section G3.1.11. Also
update the chilled water valves to two-way valves so that the secondary
chilled water loop operates as a variable flow loop with pumps riding
the curve. Provide updated PS-C reports confirming that the changes have
been made."
	"It is unclear why the pump flow for the secondary chilled water
loop is so much larger than that of the primary chilled water loop when
the temperature differential for both loops is expected to be the same.
It also appears based on the outputs in PS-C that the secondary chilled
water loop is operated at the same load for every hour that it is on
even though it is a variable speed pump. Please update the secondary
chilled water loop flow to be consistent with the primary chilled water
loop flow, and confirm that the secondary chilled water loop is
operating as a variable flow loop."
	 
	I have to say:
	I didn't see any equest-model modeled with separate condenser
water and chilled water pumps interlocked to operate with each
associated chiller. 
	I manually resized the boilers and chillers with reference to
SS-D report, because auto sizing of eQUEST generated capacities that
were double the size of SS-D report. Resizing of the volume flow of
secondary loop of chillers according to primary loop of chillers
generated warningmessages but changed nothing.
	 
	Heinrich
	 
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