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[EnergyPlus_Support] Re: ASHRAE 90.1 - Fan Power

Thanks James.

In this case, I have 6 objects under "Fan:OnOff" which I understand are the HVAC system fans. For my Baseline ASHRAE case the "Maximum Flow Rate" (m3/s) is "autosize". I also have my "Fan Efficiency" and "Motor Efficiency". 

I assume the "Delta P" that you're referring to is "Pressure Rise" (Pa), which in my case is currently set at 50. Please confirm. I can change this value. 

Where do I find my "K" value? I will need this in order to back-calculate my fan power.

I have another question regarding fans, is it possible to model the exhaust fans (which are independent of the HVAC units) in addition to the ventilation fans and the HVAC supply fans?

As I understand it, all HVAC system fans are lumped together into "Fans" but it seems to be required by 90.1 that the fans are modeled separately depending on the characteristics. Am I correct in my reading of 90.1? Is E+ capable of modeling them separately?

Thanks again James. You've been a great help!

Brendan

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Brendan,
> 
>  
> 
> Flow X Delta P x K / Fan efficiency / Motor efficiency = BHP or W
> 
>  
> 
> In order to get an autosized fan to result in the proper power for 90.1, you
> probably want to derive the appropriate delta P based on your motor and fan
> efficiencies.  (Double-checking the results against 90.1 is also good!)
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of bcmcgr
> Sent: Friday, February 18, 2011 3:12 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] ASHRAE 90.1 - Fan Power
> 
>  
> 
>   
> 
> All,
> 
> It is my understanding that according to ASHRAE 90.1 Appendix G fan power
> must be modeled for the Proposed and Baseline models but I do not see a
> place to input hp into E+. I'm under the impression that the fan operates on
> a power curve within E+ and that the fan power cannot be directly input. Is
> this correct? How do you all satisfy this requirement of 90.1?
> 
> Brendan
>




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