Re: [EnergyPlus_Support] DX Heating Coil HSPF

The HSPF is impacted by the COP of heating, part load factor, and the supply fan electric power per unit air flow rate. For instance, ECM motors my require less power input for the same external pressure. Thus, fan electric power per unit flow rate [W/(m3/s)] can be up to 50% lower than the default values stated in the standard (AHRI Std 210/240).

One important factor that is commonly overlooked is the "Outdoor Dry-Bulb Temperature to Turn On Compressor", which is an input field in the DX heating coils, is used only for HSPF calculation. For some ranges the higher the value of this input field, the lower the HSPF calculated would be all other inputs being the same. I suggest that you also try to change the value of this input field to see its impact on HSPF. 

Increasing the heating COP excessively may not be good idea even if it gives you a reasonable HSPF value as it may cause way too low HVAC electric energy use.

Hope this helps.
 
Bereket Nigusse
Florida Solar Energy Center



    From: "iluminasol33@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
 To: EnergyPlus_Support@xxxxxxxxxxxxxxx 
 Sent: Thursday, February 19, 2015 3:46 PM
 Subject: Re: [EnergyPlus_Support] DX Heating Coil HSPF
  

 Thank you Jean for your answer, I will try your suggestion and will let you know once I solve it. 

Additionally, I received the following comment from the LEED reviewer:

"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 Userâ??s Manual showing that the calculation
has been performed at ARI-rated conditions."

I am sure that Energy Plus performs this automatically, but what I do not know is how to justify this to the reviewer, any suggestions? 

Regards,
Santiago 

__._,_.___

Posted by: Bereket Nigusse <nigusse_ba@xxxxxxxxx>

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