[Equest-users] Separating Fan Energy from EER

[Maria Karpman]

Bill, 

 

I agree that the fan power at ARI conditions, and not the Appendix G
baseline fan power (#2 in Nick's email) should be used to calculate EIR.
Using the method that Nick described may create various anomalies, for
example negative baseline EIR in instances where Appendix G baseline fan
power is high due to allowed pressure drop adjustments from Table
6.5.3.1.1B.  

 

Thanks,

 

Maria 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bill
Talbert
Sent: Tuesday, July 12, 2011 11:00 AM
To: Nick Caton; Christian Kaltreider; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Separating Fan Energy from EER

 

Nick and Christian,

The 90.1 prescriptive performance values for unitary equipment are based on
ARI rated conditions. The 90.1 baseline fan power allowance does not
directly align with the fan energy used in the ARI test. The fan energy in
the ARI test is based on 365 W/1000 CFM and 400 CFM/12000 Btu/h. I believe
you should use your baseline system equipment capacity (Btu/h or KW) to
calculate the amount of fan energy to 'extract' from the cooling equipment
EER/SEER/COP rather than the 90.1 baseline fan power allowance as indicated
below in step 4. If you use the 90.1 baseline fan power allowance, you could
be removing a larger fan power value, making the cooling equipment more
efficient in the baseline than the tested performance requires.

 

Also, the ARI tests are based on specific temperature conditions so you may
need to adjust for project specific design conditions.

 

Regards,

Bill

 

 


Bill Talbert  PE, LEEDR AP
Sustainable

 

AEI | AFFILIATED ENGINEERS, INC.  
5802 Research Park Boulevard | Madison, WI  53719

P: 608.441.6677 | C: 608.234.3803 | F: 608.238.2614    
 <mailto:btalbert at aeieng.com> btalbert at aeieng.com  |
<http://www.aeieng.com/> www.aeieng.com  

 

 

 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Monday, July 11, 2011 9:52 AM
To: Christian Kaltreider; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Separating Fan Energy from EER

 

Hi Christian,

 

USGBC/LEED/90.1 does not officially sanction or require any eQuest-specific
procedure (nor any other program), so ultimately it falls on the modelers to
know what the heck we're doing and be able to defend it in cases like this.


 

As a qualifier, not all efficiency ratings are fan-energy-inclusive.  For
those that are, the procedure I follow (using a spreadsheet) is to
basically:

1.       Using the maximum design capacity, translate the
prescribed/scheduled efficiency from SEER/EER to kW input at maximum
capacity.  You may have noticed there's more than one SEER equation out
there: For seasonal efficiencies (SEER/AFUE), there are various formulae for
conversion to steady-state efficiencies (EER/COP) that vary based on what
kind of equipment you're dealing with.  You'll also find that certain
equipment like heatpumps have multiple equations referenced, as there are
multiple white papers published over the decades that attempt to establish a
relationship between nominal seasonal efficiency and steady-state
efficiency, where each study sampled different equipment from a different
period of time.  What does this mean for today's LEED modeler?  There are
multiple right answers (provided you know where you're coming from).  To
give a more concrete response on this point, here are the equations I have
collected and currently use for baseline system seasonal efficiencies (with
references):

 


EER=f(SEER):

 
<http://apps1.eere.energy.gov/buildings/publications/pdfs/%20building_americ
a/house_simulation_revised.pdf> [Reference: NREL Building America House
Simulation Protocol (Revised), citing Wassmer, M. (2003). A Component-Based
Model for Residential Air Conditioner and Heat Pump Energy Calculations.]


(AC) (Baseline Systems #1, #3, #5 & #6):

EERNET = -0.0182*SEER^2 + 1.1088*SEER


(HP-cooling) (Baseline Systems #2 & #4):

EERNET = -0.02*SEER^2 + 1.1268*SEER

		

COP=f(HSPF):

[Reference: Wassmer, M. (2003). A Component-Based Model for Residential Air
Conditioner and Heat Pump Energy Calculations. Masters Thesis, University of
Colorado at Boulder.]


(HP-heating) (Baseline Systems #2 & #4):

COPNET = -0.0255*HSPF^2 + 0.6239*HSPF

		

HIR = f(AFUE):

[Reference: California Energy Commission's 2005 "Nonresidential Alternative
Calculation Method (ACM) Approval Manual"]


For single packaged central furnace (baseline system #3):

HIR = (.005163*AFUE+0.4033)^-1


For Boilers where 75 ? AFUE < 80 (Baseline systems #1, #5 &#7):

HIR = (0.1*AFUE+72.5)^-1*100


For Boilers where 80 ? AFUE < 100 (Baseline systems #1, #5 &#7):

HIR = (0.875*AFUE+10.5)^-1*100

 

*Note: The cited references above are freely accessible on the internet,
last time I checked.  If anyone has a "better" equation to suggest, (knowing
where the equation came from), please share!  

 

2.       For baseline systems, calculate the system fan energy Pfan.  For
proposed systems, calculate the actual system fan energy in kW.

3.       Using the system fan design airflow(s), enter the calculated fan
energy as kW/CFM under airside systems tab.

4.       Subtract #2 from the cooling "kW input" in #1 - this is the
"other-than-fan energy."  Using the design cooling capacity for the system,
turn that into an EIR figure for input in the model.

 

Those who make the effort to understand what's happening have the right
idea.  Relying on others' work and tools without fundamental understanding
on occasion is necessary, but it's a slippery slope to be sure.  

 

Best of luck to you!

 

~Nick

cid:489575314 at 22072009-0ABB

 

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, July 11, 2011 7:43 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Separating Fan Energy from EER

 

Hi All,

 

There are strings about this subject in the archives, but they do not fully
answer my questions and I am not able to open some of the key attachments.
Here is my question:  Is there a LEED-accepted method for separating out fan
energy from an EER?  I am looking for how this can be done without eQUEST
doing some behind-the-scenes calculations/assumptions.  There is an equation
that was given in a former string, but I don't know its source or whether it
is an accepted method by the reviewing committee.  Again, I am looking to be
able to show how this is done by hand:not how to get eQUEST to do it for me.

 

Thanks very much for your help,

Christian

 

 

Christian Kaltreider, LEED AP

Energy Engineer

Sud Associates, PA

(828) 255-4691

ckaltreider at sudassociates.com

 

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110712/3d7a5f9e/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1459 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110712/3d7a5f9e/attachment-0002.jpeg>