[Equest-users] Indoor fan separation at ARI

Wed Jun 10 07:10:59 PDT 2015

Note that 90.1 2013 finally supplied the “official” formulas for extracting fan power from EER, SEER, COP47, and HSPF ratings. The resulting EIR is slighting different compared to the eQUEST formulas discussed below that many of us have been using – for example, the ASHRAE equations account for system capacity, resulting in varying EIR depending on system size.  

For Baseline HVAC Systems 1,

2, 3, 4, 5, and 6, calculate the minimum COPnfcooling and

COPnfheating using the equation for the applicable performance

rating as indicated in Tables 6.8.1-1 through 6.8.1-4.

Where a full- and part-load efficiency rating is provided in

Tables 6.8.1-1 through 6.8.1-4, the full-load equation below

shall be used:

COPnfcooling = 7.84E-8 × EER × Q + 0.338 × EER

COPnfcooling = –0.0076 × SEER2 + 0.3796 × SEER

COPnfheating = 1.48E-7 × COP47 × Q + 1.062 × COP47

(applies to heat-pump heating efficiency only)

COPnfheating = –0.0296 × HSPF2 + 0.7134 × HSPF

where COPnfcooling and COPnfheating are the packaged HVAC

equipment cooling and heating energy efficiency, respectively,

to be used in the baseline building, which excludes

supply fan power, and Q is the AHRI-rated cooling capacity

in Btu/h.

EER, SEER, COP, and HSPF shall be at AHRI test conditions.

Fan energy shall be modeled separately according to

Section G3.1.2.10.

-- 

Maria Karpman LEED AP, BEMP, CEM

________________

Karpman Consulting

 <http://www.karpmanconsulting.net/> www.karpmanconsulting.net 

Phone 860.430.1909 

41C New London Turnpike

Glastonbury, CT 06033

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Elizabeth Gillmor
Sent: Tuesday, June 09, 2015 11:32 AM
To: Jones, Christopher
Cc: equest
Subject: Re: [Equest-users] Indoor fan separation at ARI

Chris you are right, the unit labels should have been W/cfm not kW.  Thanks for the catch!  

Inline image 2

Elizabeth Gillmor  PE, LC, LEED AP

e n e r g e t i c s  consulting engineers, llc

energetics-eng.com

c 303.619.0091

On Tue, Jun 9, 2015 at 8:49 AM, Jones, Christopher <Christopher.r.Jones at wspgroup.com> wrote:

Just checking but 0.365 kW/cfm seems pretty high.  That is 356 W/cfm.  The DOE2.2 default is 0.0006 kW/cfm, 0.6 W/cfm for the PSZ system

cid:image003.png at 01D09C46.E75BA0D0

Christopher Jones, P.Eng. 
Senior Engineer

WSP Canada Inc.

2300 Yonge Street, Suite 2300

Toronto, ON M4P 1E4
T +1 416-644-4226 <tel:%2B1%20416-644-4226> 

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C +1 416-697-0065 <tel:%2B1%20416-697-0065> 

www.wspgroup.com <http://www.wspgroup.com/>  

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Elizabeth Gillmor
Sent: Tuesday, June 09, 2015 10:09 AM
To: Omar ElRawy
Cc: equest
Subject: Re: [Equest-users] Indoor fan separation at ARI

I seem to get this comment frequently so I have it all typed out as a stock LEED comment response.  The advice you received is correct. You can use the following formulas for fan power and EIR:

kW/cfm = BHP / 0.746 * Fan Motor Efficiency     (<----from Appendix G)

BHP = CFM * 0.0013 + Pressure Drop Adjustment

The baseline EIR is then calculated with fan energy modeled separately, using the following formula (same as what eQuest uses in Wizard mode):

Inline image 1

Where ARI Fan Power = fan power at rated ARI conditions (W/Btuh), and CAP = total cooling capacity (Btuh).  At rated ARI conditions, the supply fan is rated at 0.365 kW/cfm and 400 cfm/ton, such that:

Inline image 2

When normalizing the cooling capacity, the formula is:

Inline image 3

When applied to a baseline EER=9.5, the resulting EIR=0.3051.  The eQuest wizard will also do this for you correctly, but usually at LEED submittal time we are all well past the wizard phase, so the formulas above are handy to have.  

Good luck!

Elizabeth

Elizabeth Gillmor  PE, LC, LEED AP

e n e r g e t i c s  consulting engineers, llc

energetics-eng.com

c 303.619.0091

On Tue, Jun 9, 2015 at 3:26 AM, Omar ElRawy <omaroelrawy at gmail.com> wrote:

Dear all,

               I've got the following reply for a psz system in the baseline case during preliminary LEED design submittal:

"Note that section G3.1.2.1 requires 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. Because the efficiency ratings are calculated at ARI-rated conditions, the fans should also be broken out at ARI-rated conditions. Most simulation software programs have the capability to perform this step automatically. Provide documentation showing that this calculation has been performed by the software automatically or provide calculations consistent with the ASHRAE 90.1-2007 User’s Manual showing that the calculation has been performed at ARI-rated conditions."

What I did is that I referred to eQuest library, and documented the following paragraph to the reviewer:

"COOLING-EIR:
The Electric Input Ratio (EIR), or 1/(Coefficient of Performance), for the cooling unit at ARI rated conditions..... This EIR is at ARI rated conditions, i.e., without correction for different temperature or part load. Note: If you include fan electric energy consumption in your value of COOLING-EIR, then you should set SUPPLY-KW/FLOW to zero. Otherwise, the supply fan electrical energy will be double counted........ Imbedding the fan energy into the COOLING-EIR is valid only if the fan is constant volume and INDOOR-FAN-MODE = INTERMITTENT; i.e. the fan cycles on/off with the compressor. If the fan runs continuously during occupied hours, or the fan is variable volume, then the fan energy cannot be included in the COOLING-EIR (or HEATING-EIR)."

And I did set fan kw/cfm to zero, intermittent, and constant volume, but I've got the SV-A report reporting zero kw power demand, and zero fan (kw) for the system and its zones.

Then I got an advice stating that:

"You should do what the reviewer mentions, divide the indoor fan from the efficiency rating at ARI-rated conditions and model it separately; this way you will be able to report the appropriate fan power"

My question is: where do I separately input the indoor fan power (kw), and what value should it be?, knowing that this is a baseline case that do not refer to an actual design.

Thanks,

Omar ElRawy, LEED AP BD+C

LEED Project Manager

EA Sustainable Building Consultants

http://www.ea-buildingconsultants.com <http://www.ea-buildingconsultants.com/> 

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