[Bldg-sim] ASHRAE Appendix G EER Calculation

[Nick Caton]

Hi Karen,

 

The glossary definitions I'm summing up below include specifically:

-          seasonal energy efficiency ratio (SSEER)

-          energy efficiency ratio (EER)

 

There are also definitions for the various sorts of COP and seasonal
COP.  Unless noted otherwise, assume any reference to these efficiency
metrics elsewhere in the standard follow these definitions.

 

My suggestion is merely a reminder that the definitions are always a
good place to start or review when in doubt - I personally return often
to verify things whenever I have to make interpretations or cite the
standard.

 

Best of luck!

 

~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: Maria Karpman [mailto:maria.karpman at karpmanconsulting.net] 
Sent: Tuesday, February 01, 2011 10:07 AM
To: 'Karen Walkerman'; Nick Caton
Cc: 'bldg-sim at lists.onebuilding.org'; 'Sam Mason'
Subject: RE: [Bldg-sim] ASHRAE Appendix G EER Calculation

 

Karen,

 

You can download ARI 340/360 referenced in the rightmost column of
ASHRAE 90.1 Table 6.8.1 A from 
http://www.ahrinet.org/App_Content/files/standards%20pdfs/ANSI%20standar
ds%20pdfs/ANSI%20AHRI%20340-360-2007.pdf (it's free). Section 6.1 of the
ARI standard reiterates that indoor fan power must be included in the
rating, which is consistent with definitions in 90.1 quoted by Nick. The
section also provides standard fan power of 365 W per 1000 CFM (see top
of page 11), which is used in eQUEST EER to EIR conversion paper that I
emailed yesterday. The equations in the paper are principally the same
as in the ASHRAE User Manual section that Sam sent to the forum, except
the rating conditions are used for fan energy.  

 

Thanks,

 

Maria 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen
Walkerman
Sent: Tuesday, February 01, 2011 10:41 AM
To: Nick Caton
Cc: bldg-sim at lists.onebuilding.org; Sam Mason
Subject: Re: [Bldg-sim] ASHRAE Appendix G EER Calculation

 

Hi Maria,

 

Thanks for your response.  Can you provide a direct link to the AHRI
page that has the fan power rating conditions?

 

Hi Nick,

 

Thanks for your response.

 

I haven't found anything in the glossary that helps me.  Are there any
specific references you can point me to?

 

Thanks

 

--

Karen

 

 

 

On Mon, Jan 31, 2011 at 6:44 PM, Nick Caton <ncaton at smithboucher.com>
wrote:

Hi Karen,

 

Apologies if I haven't been following closely enough, but I think you
may be unnecessarily complicating the issue for yourself... if in doubt,
turn to the 90.1 glossary (section 3) regarding whether the efficiency
metrics are/aren't inclusive.  

 

EER is a simple ratio of total input power to net cooling capacity.  It
includes fan power.  SEER is the same idea, only it's weighted over a
"normal" annual period.  Again it includes fan energy.

 

While pulling the (calculated) baseline fan energy out of the prescribed
EER/SEER values may result in "unrealistic looking" efficiencies, that's
normal because fans are a big part of energy used by packaged equipment!


 

Put simply and correcting your last statement:  All Appendix G baseline
model system types require fan energy calcs.  These energies can be
subtracted from the "fan-inclusive" EER/SEER efficiencies prescribed in
Section 6 to determine cooling EIR figures.  

 

Hope that helps! 

 

~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 <http://www.smithboucher.com>  

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen Walkerman


Sent: Monday, January 31, 2011 4:55 PM

To: Sam Mason; bldg-sim at lists.onebuilding.org


Subject: Re: [Bldg-sim] ASHRAE Appendix G EER Calculation

 

Hi Sam,

 

I guess my question is the definition of "packaged" for the baseline
system case.  Systems 1 and 2 are very clearly packaged systems, with
relatively low fan power.  The fan power calculation reflects this, with
much lower fan powers for these systems.  However, systems 5 and 6 are
called "packaged" systems, but these systems typically serve a large
portion of a building with more extensive ductwork and higher fan powers
(reflected in the fan power calculation), subtracting out fan powers
from these systems and manipulating the EER of these systems results in
very high EERs (upwards of 18???).  

 

It is unclear to me which air conditioners listed in section 6.8 have a
rating which includes fan power and which do not.  I am assuming that
where different "single package" and "split system" EERs are given, that
the first includes fan energy while the second does not.

 

Anyway, it seems that to model baseline systems, the simplest approach
is to choose the split system EER (if listed) in section 6.8, and
calculate the fan power according to the G3.1.2.9 guidelines.
Therefore, the only time you would have to do the calculation mentioned
by Sam is for a proposed design system where the fan energy is included
in the EER.

 

--

Karen

 

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Monday, January 31, 2011 4:58 PM
To: Arpan Bakshi; Sam Mason
Cc: bldg-sim at lists.onebuilding.org


Subject: Re: [Bldg-sim] ASHRAE Appendix G EER Calculation

 

Mr. Sam is referencing/providing:

 

User's Manual for ANSI/ASHRAE/IESNA Standard 90.1-2007

Example 11-C  "Calculating COP for Compressor and Condenser"

 

(Found on page 11-18)

 

~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 <http://www.smithboucher.com>  

 

 

On Mon, Jan 31, 2011 at 5:30 PM, Sam Mason <sam.mason at atelierten.com>
wrote:

Karen,

>From the user's guide, the fan power should be removed from the standard
EER rating of packaged cooling systems. Excerpt below but let me know if
you have any further questions.

 

A 15-ton packaged rooftop single-zone system having an EER of 8.6 (COP
of 2.5) is

specified for a building. The following table gives the design
specifications. How should

this be modeled?

Equipment parameter                               Value

Net Cooling Capacity (Btu/h)                   174,000

Total Packaged Unit Input Power (W)        20,128

EER                                                         8.64

Gross Cooling Cap (ARI conditions)         182,000

A

The supply fan power is the difference between the gross and the net
cooling capacity.

Supply Fan Power  = (182,000 - 174,000 Btu / h) / 3.413 Btu /W h =  2343
W

 

>From the equation for cooling system COP, the cooling provided by the
compressor and

the condenser into the airstream in Btu/h per Btu/h of electrical power
input is:

COP  = (182,000 Btu / h) / {(20,128 - 2343 W)* 3.413 Btu / W h } = 3.0

Some simulation programs use an energy input ratio (EIR), which is
1/COP. In this case,

the EIR for this piece of equipment would be 1/3 or 0.333.

 

--

Sam Mason

Atelier Ten

 

T  +1 212 254 4500 x221

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen Walkerman
Sent: Monday, January 31, 2011 3:53 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE Appendix G EER Calculation

 

A clarification:

 

My question pertains to baseline models, with baseline systems.

 

--

Karen

 

On Mon, Jan 31, 2011 at 12:09 PM, Karen Walkerman <kwalkerman at gmail.com>
wrote:

Hi All,

 

G3.1.2.1 in ASHRAE 90.1 says that "Where efficiency ratings, such as EER
and COP, include fan energy, the descriptor shall be broken down into
its components so that supply fan energy can be modeled separately."

 

However, I am a little unclear as to which baseline systems this applies
to.  It seems that it would apply to systems 1 - 2, and not to systems 3
- 8?

 

Thanks,

 

--

Karen

 

 

 

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