[Equest-users] Indoor fan separation at ARI

[Elizabeth Gillmor]

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):


[image: 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:


[image: Inline image 2]


When normalizing the cooling capacity, the formula is:

[image: 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:*
>
>
> *"N*ote 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
>
>
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