[Equest-users] Wizard DX EER Correction

[Paul Riemer]

I thought Andrew said this mostly well but maybe equations would help.

EER = (Cooling Output Btu/hr ) / (Supply Fan W + Compressor W + Condenser Fan W)

COP = Output / Input and is unitless

EIR = 1/COP (so it is also unitless) = (Compressor Input + Condenser Input) / (Cooling Output)

So hopefully you see that EIR does not include supply fan energy.  All fan energy is modeled in DOE-2 based on the separate fan energy inputs and assumptions.  Of course ASHRAE 90.1-2004 Section 6 and Appendix G including amendments prescribe baseline fan power limits and part load performance.

I believe the Standard Test Procedure for determining the EER rating includes a prescribed external static pressure but exactly what portion of the total unit electric energy is due to the supply fan would vary a little from unit to unit based on type of fan, internal static losses, etc.

So the eQUEST WIZARD is removing an assumed standard fan component from the entered EER and doing a units conversion to determine a cooling efficiency (EIR) for DOE-2.

I have in my files:

EIR =  (1/EER-0.012167)/((1/3.413)+ 0.012167)
EIR =  (1/SEER*0.778+1.4)-0.012167)/((1/3.413)+ 0.012167)

I do not recall where I found this but obviously I attribute it to the above eQUEST development team. I do apologize if it is out of date, misinterpreted, or mistyped.

I encourage digging deep through the program, its help files, and the various archives and also attending a training session like the Energy Center of Wisconsin's with Marlin Addison.

Paul Riemer


________________________________
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby Oylear
Sent: Wednesday, August 13, 2008 1:19 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Wizard DX EER Correction

Sorry to dig up an old topic, but I have a question about the wizard that was talked about a year ago.  As mentioned below, the wizard will change the efficiency you input into the program, but I can not figure out what the change is based on.  One would assume its taking into account the fan power, but by changing the fan bhp entry in the wizard I see no change in the EIR that is output by the wizard.

Does anyone have any insight as to how the wizard reaches the resulting EIR for DX units?

Robby Oylear
Mechanical Engineer
direct: 206.788.4571
cell: 206.354.2721
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From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Andrew Craig
Sent: Wednesday, August 29, 2007 12:06 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] a qucik question about Cooling EIR -- eQuest


Anna---

The EIR in eQUEST is the combined efficiency of the unit condenser and compressor while the ASHRAE code EER or SEER values are the entire packaged unit efficiency.  You'll notice if you enter a published EER or SEER in the wizard and then check the EIR output in the detailed edit mode, it does not equal 3.413/EER because it isn't taking into account the fan efficiency or inefficiency depending on how you look at it.

If you are doing a model for LEED, the way I have been advised to model packaged units is to enter the ASHRAE Table values in the wizard (EER or SEER) and let the program parse out the components of EIR and fan power.  Then, calculate the baseline fan efficiency and enter that number in the detailed edit mode, overriding the wizard created value.

I have heard from members on the ASHRAE committee that Appendix G does not handle this issue very well and it seems to be something that could be refined.  If anyone out there has a more definitive stance on the proper way to model packaged units in eQUEST with regards to ASHRAE/Appendix G, please chime in.

Regards,

Andrew Craig, EIT, LEED(r) AP | Mechanical Designer

INTERFACE ENGINEERING

708 SW Third Avenue | Suite 400 | Portland, OR 97204

direct: 503.382.2696

office: 503.382.2266

fax: 503.382.2262

email: Andrew_C at ieice.com

web: www.ieice.com

Consultants of Choice to the Built Environment for over 35 years

Kirkland, WA | Portland, OR | Sacramento, CA | Salem, OR | SanFrancisco, CA

-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Anna Liu
Sent: Wednesday, August 29, 2007 11:38 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] a qucik question about Cooling EIR -- eQuest

Hello all,

I have a quick question about the Cooling EIR in

eQuest. If I got COP from ASHRAE90.1-2004 Table 6.8.1,

then EIR=1/COP. Does this caculation include the

supply fan electrical energy already or not?

Thanks for your help.

Regards,

Anna




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