High pumps equivalent full load hours in the model

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Hello all,

I received following LEED review comment:

?The Baseline model pumps equivalent full load hours (determined by
dividing the total annual pumps consumption (45,761 KWH) by the pump peak
demand (5.426 KW) reflected in the simulation output report) is 8,433
hours/year, which is unexpectedly high given the anticipated schedule of
operation for the project.?

This is a 9 story residential building with unfinished retail space in the
ground floor. Primary HVAC system in the baseline case is PTAC and the
secondary system that serves non-residential spaces is System 7 ? VAV with
reheat and chilled water. HVAC system in unfinished retail space of the
propose model is System 7 as well. Pumps equivalent full load hours for the
proposed model is 8,089 hours/year (15,401/1.905), which is close to EFLH
of the baseline case.

Is this high EFLH loads relate to the primary and secondary pumps in both
of the models and are justifiable or there is something wrong with the
models. Attached are inp and pd2 files of the baseline model from version
3.65 build 7173.

Thank you for your help,

Morteza Kasmaei
Senior Architect
LEED AP BD+C, GGP

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Hi Morteza,

I looked at the file quickly and it seems that there are some changes that you can make to reduce the EFLHs slightly (I was able to get it to 8,146 hours/year by changing to two-way HW and CHW coils, moving cooling coils to secondary loop, readjusting pump flows and power after other changes, and setting loop operation to demand), but it seems like the underlying cause of the high EFLHs is probably due to having VAV systems which only serve interior spaces which are probably going to be in cooling mode year round.

Note that I think you can model the corridors on floors with residential as PTACs also. I believe that the reviewer should allow you to be flexible in how you define the corridor off of residential spaces. This might help reduce the pump EFLHs for primary and secondary chilled water pumps, assuming those VAVs which only serve core spaces are part of what is driving the high EFLHs.

Alex Chapin EIT, BEMP, LEED AP BD+C, O+M
Energy Engineer | Mason & Hanger
A Day & Zimmermann Company
D 804.521.7072 | O 804.285.4171 | F 804.217.8520
4880 Sadler Road, Suite 300 | Glen Allen, VA 23060
masonandhanger.com
Building a More Secure World

Chapin, Alex N's picture
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Not to make this more difficult than necessary, but could I take a step back and ask: Can anyone comment regarding what exactly between LEED and/or 90.1 precludes 24/7 hydronic loop circulation?

This is NOT an uncommon control scheme to encounter in the real world, and the inherent simplicity of 24/7, constant-speed operations carry some real advantages with respect to system first-cost, simplicity / troubleshooting, and maintenance over time.

That?s not to say variable flow pumps, demand based on/off controls, and other schemes are a bad idea (I?m regularly implementing such strategies where it pencils out), but I?ve encountered a number of cases where variable-flow upgrades implemented badly can end up causing more harm ($$$/downtime) than good.

I am left sincerely interested to learn and understand what exactly the LEED reviewers may be expecting/requiring of hydronic system pumping operations.

Thanks,

~Nick

[cid:image001.png at 01D4B19C.3EADA950]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D4B19C.3EADA950]

Nicholas.Caton at schneider-electric.com's picture
Joined: 2016-02-26
Reputation: 0

If the energy (kWh) of the pump divided by the peak demand (kW) is something close to 8760, this indicates not only that the pump is running 24/7, but that the pump power does not vary. Some baseline loops are required to have VSD pumps. But even single-speed pumps are required to be ?variable flow? by ?riding the pump curve?. To model this, you have to use two-way valves. Alex Chapin mentioned this in his reply below. When you make the changes Alex describes below (and one more ? remove the process load on the secondary chilled water loop), the EFLH drops down to around 6,000 hours for all three loops.
~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP
Senior Energy Engineer

[Pathfinder-EA-logo-2]T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
134 South Fitzhugh Street
Rochester, NY 14608 [cid:image007.png at 01D4B4BB.754D9610] Ask me why Carbon Fee & Dividend may be right for you.

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Nick, nothing precluded in the proposed case ? these aren?t from the mandatory section ? however the baseline is supposed to include the applicable energy efficiency measures as you?ve described. I think you (Morteza) should follow up with Alex?s comments about how the building is divided and baseline systems assigned.

EFLH means running at full capacity though, so although this system may need to be available year-round or nearly year-round, why aren?t some portions of it closing down? In a nutshell ? I?m not sure the system selection is correct and you may be able to make an end-run on the issue altogether. I unfortunately don?t have time to dig through the model files (or even verify which version of 90.1 is being discussed), but the setup is not typical for what I?m seeing in practice now (LEED, Green Globes, or not certified), and also not knowing the areas of all these components entering the system selection matrix.

I agree with Alex?s point that the corridor system would be separate in the system selection from the retail, and also the residential units. The typical setup that we?d see in this case is a make-up air unit, potentially DX, and which according to many building codes supplies the same volume of 100% outside air at all times to make up the kitchen (hopefully?), in-unit clothes dryer if applicable, and bathroom exhausts. It could vary airflow if the exhaust air from the apartments was known to vary. To Nick?s point ? that?s a complicated system for a baseline. For the most advanced energy efficiency cases, perhaps a DOAS unit with heat recovery. (One clue would be does the proposed building also have a DOAS that serves only the apartment stack?) PTAC per floor for corridor area might also be justifiable.

Then the retail unit would be separate ? besides different operating schedule the tenant would pay for their own utilities so it is not likely to be combined with the corridor AHU on a hydronic system. Only in the largest buildings would these end up being hydronic systems with submetering. This will most likely be its own DX VAV or maybe CHW system, it should have its own outside air supply pathway, etc.

David

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Associate

Direct: (847) 316-9224 | Mobile: (773) 490-5038

Grumman/Butkus Associates | 820 Davis Street, Suite 300 | Evanston, IL 60201
Energy Efficiency Consultants and Sustainable Design Engineers

grummanbutkus.com | Blog | Facebook | Twitter

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@David Eldridge, Bill Bishop, & Kathryn Kerns: Thank you for your immediate/parallel responses! That?s exactly the sort of discussion & feedback I was hoping to spark and for all of us to learn from.

I am a couple years distanced today from when I was breathing LEED 365 days/yr as an independent consultant, so I?m keen to keep a pulse on how the standards and rating systems of the day continue to push the envelope forward on systems engineers and designers.

I feel the first decade+ of my career was focused on learning to design & specify ever more complex systems and operations. My more recent years have exposed me to repeated cases of ?death by complexity? however, and so I?m bearing back a bit towards questioning the value of some such decisions. In broad terms, I think well-meaning and intelligent engineers can often fall into the trap of designing fighter jets for cab drivers. Sometimes the most correct energy solution on paper misses the end-users and operators who will make or (emphasis) break the realized savings. Learning to balance the optimal level of design and operation complexity is an area of focus for me these days.

Kind regards,

~Nick

[cid:image001.png at 01D4B4C4.B39827B0]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D4B4C4.B39827B0]

Nicholas.Caton at schneider-electric.com's picture
Joined: 2016-02-26
Reputation: 0

To All,

Not sure if this helps, but looking at the input file there appears to be a sizable process flow on the secondary chilled water loop with no related load. The schedule of use is tied to an occupancy schedule which is relatively high and flat.

I am not sure why this load is on the loop, but removing it makes the numbers seem far more reasonable for the application.

"Secondary Chilled Wate Loop" = CIRCULATION-LOOP
TYPE = CHW
SUBTYPE = SECONDARY
LOOP-DESIGN-DT = 12
PIPE-HEAD = 21.6
PRIMARY-LOOP = "Primary Chilled Water Loop"
LOOP-OPERATION = STANDBY
DESIGN-COOL-T = 44
COOL-SETPT-CTRL = FIXED
LOOP-PUMP = "Secondary CHW Loop Pump"
HEAD-SENSOR-LOCN = AT-COILS
PROCESS-LOAD = ( 0.001 )
PROCESS-FLOW = ( 96.3 )
PROCESS-SCH = ( "1FLBldg Occup Sch" )
..

Sincerely,

Joseph Lewis
Energy Analyst

Vidaris, Inc.

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Joined: 2019-01-31
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All,

This 90.1 interpretation

looks relevant to the exchange. See the quote below.

Interpretation No.1: The Appendix G requirement for the Baseline hot water
pumping system to be ?modeled as primary-only with continuous variable
flow? means that the hot water loop and pump(s) shall be modeled to operate
in ?on-demand mode?. In other words, the loop and pumps shall be modeled to
operate continuously when there is heating demand on the loop, and shall be
off during periods when there is no demand on the loop.

Question No.1: Is this interpretation correct?

Answer No.1: Yes.

Interpretation No.2: The Appendix G requirement for the Baseline primary
chilled water pumps and condenser water pumps to be ?interlocked to operate
with the associated chiller? means that the chilled water primary and
secondary loop, and the condenser water loop shall be modeled to operate in
?on-demand mode?. In other words, the primary and secondary chilled water
loop(s), chilled water pumps, condenser water pumps, and cooling tower
shall be off during periods when there is no demand on the loop.

Question No.2: Is this interpretation correct?

Answer No.2: Yes.

Maria

*From:* Equest-users *On
Behalf Of *David Eldridge via Equest-users
*Sent:* Friday, January 25, 2019 3:39 PM
*To:* Nicholas Caton ; Chapin, Alex
N ; Morteza Kasmai ;
equest-users at onebuilding.org
*Subject:* Re: [Equest-users] High pumps equivalent full load hours in the
model

Nick, nothing precluded in the proposed case ? these aren?t from the
mandatory section ? however the baseline is supposed to include the
applicable energy efficiency measures as you?ve described. I think you
(Morteza) should follow up with Alex?s comments about how the building is
divided and baseline systems assigned.

EFLH means running at full capacity though, so although this system may
need to be available year-round or nearly year-round, why aren?t some
portions of it closing down? In a nutshell ? I?m not sure the system
selection is correct and you may be able to make an end-run on the issue
altogether. I unfortunately don?t have time to dig through the model files
(or even verify which version of 90.1 is being discussed), but the setup is
not typical for what I?m seeing in practice now (LEED, Green Globes, or not
certified), and also not knowing the areas of all these components entering
the system selection matrix.

I agree with Alex?s point that the corridor system would be separate in the
system selection from the retail, and also the residential units. The
typical setup that we?d see in this case is a make-up air unit, potentially
DX, and which according to many building codes supplies the same volume of
100% outside air at all times to make up the kitchen (hopefully?), in-unit
clothes dryer if applicable, and bathroom exhausts. It could vary airflow
if the exhaust air from the apartments was known to vary. To Nick?s point ?
that?s a complicated system for a baseline. For the most advanced energy
efficiency cases, perhaps a DOAS unit with heat recovery. (One clue would
be does the proposed building also have a DOAS that serves only the
apartment stack?) PTAC per floor for corridor area might also be
justifiable.

Then the retail unit would be separate ? besides different operating
schedule the tenant would pay for their own utilities so it is not likely
to be combined with the corridor AHU on a hydronic system. Only in the
largest buildings would these end up being hydronic systems with
submetering. This will most likely be its own DX VAV or maybe CHW system,
it should have its own outside air supply pathway, etc.

David

*David S. Eldridge, Jr.**, P**.**E**.**, LEED AP BD+C, BEMP, BEAP, HBDP*

Associate

Direct: (847) 316-9224 | Mobile: (773) 490-5038

*Grumman/Butkus Associates* | 820 Davis Street, Suite 300 | Evanston, IL
60201

Energy Efficiency Consultants and Sustainable Design Engineers

*grummanbutkus.com * | *Blog
* | *Facebook
*
| *Twitter *

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *Nicholas Caton
via Equest-users
*Sent:* Friday, January 25, 2019 12:51 PM
*To:* Chapin, Alex N ; Morteza Kasmai <
morteza.kasmai at gmail.com>
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] High pumps equivalent full load hours in the
model

Not to make this more difficult than necessary, but could I take a step
back and ask: Can anyone comment regarding what exactly between LEED
and/or 90.1 precludes 24/7 hydronic loop circulation?

This is NOT an uncommon control scheme to encounter in the real world, and
the inherent simplicity of 24/7, constant-speed operations carry some real
advantages with respect to system first-cost, simplicity / troubleshooting,
and maintenance over time.

That?s not to say variable flow pumps, demand based on/off controls, and
other schemes are a bad idea (I?m regularly implementing such strategies
where it pencils out), but I?ve encountered a number of cases where
variable-flow upgrades implemented badly can end up causing more harm
($$$/downtime) than good.

I am left sincerely interested to learn and understand what exactly the
LEED reviewers may be expecting/requiring of hydronic system pumping
operations.

Thanks,

~Nick

[image: cid:image001.png at 01D4B19C.3EADA950]

*Nick Caton, P.E., BEMP*

Senior Energy Engineer
Regional Energy Engineering Manager

Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[image: cid:image002.png at 01D4B19C.3EADA950]

*From:* Equest-users *On
Behalf Of *Chapin, Alex N via Equest-users
*Sent:* Monday, January 21, 2019 7:14 AM
*To:* Morteza Kasmai ;
equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] High pumps equivalent full load hours in the
model

[External email: Use caution with links and attachments]
------------------------------

Hi Morteza,

I looked at the file quickly and it seems that there are some changes that
you can make to reduce the EFLHs slightly (I was able to get it to 8,146
hours/year by changing to two-way HW and CHW coils, moving cooling coils to
secondary loop, readjusting pump flows and power after other changes, and
setting loop operation to demand), but it seems like the underlying cause
of the high EFLHs is probably due to having VAV systems which only serve
interior spaces which are probably going to be in cooling mode year round.

Note that I think you can model the corridors on floors with residential as
PTACs also. I believe that the reviewer should allow you to be flexible in
how you define the corridor off of residential spaces. This might help
reduce the pump EFLHs for primary and secondary chilled water pumps,
assuming those VAVs which only serve core spaces are part of what is
driving the high EFLHs.

*Alex Chapin* EIT, BEMP, LEED AP BD+C, O+M
Energy Engineer | Mason & Hanger
A Day & Zimmermann Company
*D *804.521.7072 | *O *804.285.4171 | *F *804.217.8520
4880 Sadler Road, Suite 300 | Glen Allen, VA 23060
masonandhanger.com

*Building a More Secure World*

*From:* Morteza Kasmai
*Sent:* Friday, January 18, 2019 1:29 PM
*To:* equest-users at lists.onebuilding.org
*Subject:* [Equest-users] High pumps equivalent full load hours in the model

Hello all,

I received following LEED review comment:

?The Baseline model pumps equivalent full load hours (determined by
dividing the total annual pumps consumption (45,761 KWH) by the pump peak
demand (5.426 KW) reflected in the simulation output report) is 8,433
hours/year, which is unexpectedly high given the anticipated schedule of
operation for the project.?

This is a 9 story residential building with unfinished retail space in the
ground floor. Primary HVAC system in the baseline case is PTAC and the
secondary system that serves non-residential spaces is System 7 ? VAV with
reheat and chilled water. HVAC system in unfinished retail space of the
propose model is System 7 as well. Pumps equivalent full load hours for the
proposed model is 8,089 hours/year (15,401/1.905), which is close to EFLH
of the baseline case.

Is this high EFLH loads relate to the primary and secondary pumps in both
of the models and are justifiable or there is something wrong with the
models. Attached are inp and pd2 files of the baseline model from version
3.65 build 7173.

Thank you for your help,

Morteza Kasmaei
Senior Architect

LEED AP BD+C, GGP

______________________________________________________________________
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