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RE: [EnergyPlus_Support] Simple way to account for motor casing heat





The 20kW of OtherEquipment doesn’t add to the electricity consumption meter, it just adds heat load to the zone.  This is to replace the 20kW of heat “lost” by the pumps -- heat that originally came from electricity used by the pumps.  ElectricEquipment would add 20kW to the electricity meter thus double counting the 20kW of electricity.

 

A few types of equipment, like water heaters, already do add their skin losses to zone.  The wish list does include getting all types of equipment inefficiencies coupled to zone loads.

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of James V Dirkes II, PE
Sent: Tuesday, September 07, 2010 4:24 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Simple way to account for motor casing heat

 

 

Dear Brent,

 

I’m missing something…..

If the energy is already accounted for in, say, the pump object,

 

How can it be that adding an OtherEquipment object with 20kW doesn’t double count?

 

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 Griffith, Brent
Sent: Tuesday, September 07, 2010 5:56 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Simple way to account for motor casing heat

 

 

OtherEquipment is less hassle than ElecticEquipment, it does not consume energy that would need to be backed out to avoid double counting.

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jvd2pe
Sent: Tuesday, September 07, 2010 3:12 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Simple way to account for motor casing heat

 

 

Dear Forum,

Life is good! Big problems are (mostly) solved, so I'm turning my attention to smaller ones.

Has anyone come up with a simple way to add motor casing heat to a zone so that the HVAC system treats it as a heating / coolning load?

For example:
* I have 200kW of pump motors in a mechanical room
* Each motor is 90% efficient
* This means that 20kW (10%) is lost from the motor to the adjoining mechanical room zone
* the entire 220kW will be accounted for by E+ in its energy calculations, but the HVAC system in the mechanical room never "sees" the 20kW and therefore cannot respond properly.

My best solution thus far is to add the 20kW into the zone as "OtherEquipment" or "ElectricEquipment", and then back it out from the electricity totals (so it won't be counted twice).

That's too much effort for a relatively small amount of energy in my opinion!

Better idea, anyone? (Thanks in advance.)



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