[Bldg-sim] ASHRAE Appendix G EER Calculation

[Maria Karpman]

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%20standards%2
0pdfs/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

 

Image removed by sender. cid:489575314 at 22072009-0ABB

 

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

 <http://www.smithboucher.com> 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

Image removed by sender. cid:489575314 at 22072009-0ABB

 

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

 <http://www.smithboucher.com> 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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