[BLDG-SIM] Calculating EIR from SEER

[Pat Bailey]

Bryce,

The CEC method is required for compliance purposes, but many use simpler
methods such as converting the SEER to EER by using a multiplier (0.85  to
0.95 are often used) and then converting the EER (95/67) to EIR using a
straight unit conversion.  RESNET which is the body that I've worked with on
software verification methods for nationwide HERS ratings for houses uses
the following equation:

Cooling EIR = 0.941 * (1/(SEER/3.413))

This was developed as a simplification to more complex methods and is based
on a regression analysis of numerous systems.  As I'm sure you're aware, the
conversion of SEER to EER is not exact and depends on the means by which the
manufacturer acheived the SEER.

There are then various assumptions about the part load performance of the
units, but that is another topic.

Good luck,

Pat

_______________________

Pat Bailey, P.E.
Principal
GeoPraxis, Inc
205 Keller Street
Petaluma, CA 94952

www.geopraxis.com
707.766.7010 (v)
707.766.7014 (f)



-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com]On Behalf Of Bryce
Munger
Sent: Wednesday, July 07, 2004 7:56 AM
To: BLDG-SIM at GARD.COM
Subject: [BLDG-SIM] Calculating EIR from SEER


I am looking fo a method of calculating EIR from SEER when no info is
available from the manufacturer for use in DOE-2's COOLING-EIR.  I found a
method in the "2005 Nonresidential ACM Manual, Express Terms, 15-Day
Language" text (page 2-80) that does this but there appears to be a typo in
the copy I have.

Equation N2-22 is:

EER(67,95) = 10-(11.5-SEER)x0.83 [default for SEER >15]
           = 10                  [default for SEER => 15]

Equation N2-20 is:

EERnf(67,95) = 1.0452xEER(67,85)
              + 0.0115xEER(67,85)^2
              + 0.000251xEER(67,85)^3
              x F(txv) x F(air)

where F(txv) = Refrigerant Charge Factor
             = 0.9 default
             = 0.96 for systems with verified charge

and F(air) = 1 for systems with verified airflow
           = 0.925 for default flow

and EERnf = EER with fan energy removed

Equation N2-19 is:

EIR = 3.413/EERnf(67,95)

Which is what I want to solve for.  My problem is with Equation N2-22.  The
switch conditions (yes, I typed it right) are not independent.  One of them
should be reversed to less than, but which one?  Does anyone have another
proven method of calculating EIR from SEER?

Thanks much,

Bryce K. Munger
Energy Analyst
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Balzhiser & Hubbard Engineers
100 West 13th Avenue
Eugene, OR 97401
V: (541) 686-8478
F: (541) 345-5303
bmunger at bhengineers.com
www.bhengineers.com


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