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COP and EER with and without Supply Fan Power

asked 2019-04-17 20:40:33 -0500

lrebello's avatar

updated 2019-04-19 14:47:22 -0500

Hello to all,

I have been reading a lot questions on UnmetHours forum and other foruns online but could not find te answer for my question.

The closest question I found on this topic is from @GeraldoPithon but it still doesnt answer my queston: Output "Standard Rated Net COP" in OpenStudio different from "Input Rated COP" in EnergyPlus report

So I have my own understandings and I want to know if it is valid for EnergyPlus (OpenStudio):

  1. First Understanding

The rated-high-speed-COP (see figure 1) I have entered on my Cooling Coil (object: Package-Rooftop-VAV-with-PFP-boxes) is equal to the one I see on under Nomial-Efficiency-[W/W] on Cooling Coils Table (see figure 2). Thus, this is the COP for the condenser unit(coil+pump) excluding supply fans, as we can see on a note under the mentioned table: "Nominal values are gross at rated conditions, i.e., the supply air fan heat and electric power NOT accounted for. ").

Figure 1 Figure 1 Figure 2 Figure 2

  1. Second Unerstanding

Following ASHRAE 90.1 section G3.1.2.10 and section I did my own calculations for all fan powers. ASHRAE 90.1 says I shall break those power off of each condenser COP (or EER). But as far as I am concerned, I dont need to perfom those calculations as I have both COP (including and excluding supply fans) on Tabular Outout Report from OS. I can see the COP including the supply fans under DX-Cooling-Coils Table (see figure 3), and as it says on a note under this table: "ANSI/AHRI ratings include supply fan"

figure 3 Figure 3

Did I followed a correct logic?

Thanks a lot guys

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1 Answer

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answered 2020-05-23 02:48:28 -0500

imeru's avatar

You need to input the calculated COP (remove the supply fan energy per ASHRAE 90.1-2013 G3.1.2.1) to the "Rated COP" in the OpenStudio. The Rated COP of OpenStudio is Gross Rated Cooling COP in the EnergyPlus.

Rated COP (Gross Rated Cooling COP) on OpenStudio input = Nominal Efficiency on Cooling Coils output report table > Standard Rated Net COP on DX Cooling Coils output report table

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Asked: 2019-04-17 20:40:33 -0500

Seen: 501 times

Last updated: Apr 17 '19