[Bldg-sim] Fundamentals: SEER/HSPF conversions

[Nick Caton]

Neal,

 

Thanks very much - this is very helpful and rounds out my understanding much better!

 

Regarding climate, I probably wasn't clear in my intent - I meant that the 0.875 "factor," if correctly understood to account for (among other things) the amount a unit can be expected to cycle during a cooling season, might also vary based on climate.  The idea here being that the same condensing unit will cycle on more in Florida than in Maine for the same cooling season.  If the goal is to come up with a "seasonally averaged EER," then perhaps varying that factor could do the trick?

 

Some extra google-searching has led me to this article coming out of UCF:

http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-413-04/

 

In particular, check out this interesting climate map presented as part of the conclusions showing how location-specific SEER/HSPF efficiencies can vary from ARI ratings:  http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-413-04/images/Figure5_lg.gif

 

It sounds for the moment like the SEER/HSPF -> EER formulae you've shared below might be what I'm looking for - for my part, I'll see whether I can look up that student's paper =).

 

***

 

PS: I've only picked up this [EER = 0.875 * SEER] equation from popular hear-say... After some digging I've found what looks like a plausible explanation of its source here:  http://www.udarrell.com/airconditioning_eer_ratings_over_seer_ratings_central_systems.html

"The SEER of a system is determined by multiplying the steady state energy efficiency ratio (EER) measured at conditions of 82°F outdoor temperature, 80°F dB/ 67°F wb 50% RH indoor entering air temperature by the "Part Load Factor" (PLF) of the system. 
The PLF is a measure of the cyclic performance (CD) of a system and is calculated as follows: CD is Cyclical Data
PLF    = 1.00 -  (CD X's 0.5)

"The cyclic performance (CD) value in the above equation has been determined by the government to be 0.25." The government contends that the PLF should equal:  
[1.00  -  (.25 x .5)] = .125 
1.00 - .125 = 0.875, which yields: PLF  of 0.875"

 

The same fellow goes on to cite California provides the formula [SEER = EER / 0.90] (is this a Title 24 thing?), and that for Georgia a value of 0.80 might be a better approximation constant considering the climate.

 

*** 

 

Thanks again so much!

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: Kruis, Neal [mailto:Neal.Kruis at nrel.gov] 
Sent: Tuesday, March 08, 2011 2:01 PM
To: Nick Caton; bldg-sim at lists.onebuilding.org
Subject: RE: Fundamentals: SEER/HSPF conversions

 

Nick,

 

The relationship between SEER and EER is going to vary from system to system and does not depend on the climate. Take a look at the AHRI certified product database:

 

http://www.ahridirectory.org/ahridirectory/pages/home.aspx

 

They report both SEER and EER for all air conditioners and heat pumps that have been tested. There is no way to convert directly between SEER and EER (or HSPF and COP) without having the results from the all of the AHRI tests which are usually kept confidential. The approximation of 0.875 accounts for part load cycling losses, but also how the system performs at other test conditions. It is probably a fair assumption, though you might want to check out the Building America House Simulation Protocol which uses:

 

EER = -0.02*SEER^2 + 1.12*SEER

 

This is based on a thesis written by a student at University of Colorado. The same thesis used:

 

COP_47 = -0.026*HSPF^2 + 0.624*HSPF

 

 

Here is the reference for the thesis:

 

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

 

Hope this helps,

 

 

Neal Kruis

Electricity, Resources & Building Systems Integration

National Renewable Energy Laboratory

1617 Cole Blvd. MS 5202

Golden, CO 80401

(303) 384-7384

 

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Tuesday, March 08, 2011 12:36 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Fundamentals: SEER/HSPF conversions

 

I understand HSPF is fundamentally the same thing as SEER, only it's representing a heating season instead of a cooling season.

 

When handling SEER, I used the following equation to come up with a seasonally averaged cooling EER:

 

EER = SEER * 0.875

 

My limited understanding is that 0.875 is a conceptually a constant representing a "part load cycling factor" of sorts for a typical cooling season.  I've read multiple times this constant should vary with climate (commonly, "Georgia = 0.8" and "California = 0.9").  While that makes sense to me, I've yet to see a citable climate map or similar reference breaking down what factor to use where... so up to this point I've stuck with 0.875 for simplicity's sake.

 

My root question is:  Is there a comparable "part load cycling factor," for one or more climates, for converting HSPF to a seasonally averaged heating COP/EER?

 

Put another way:  EER = HSPF * ???

 

~Nick



 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

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