# Calculate Facility Total Building Electric Demand Power

Hi everyone,

I am modeling an Room model that has ElectricEquipment:ITE:AirCooled as an IT Equipment and I modified it like below:

ElectricEquipment:ITE:AirCooled,
WestDataCenter_Equip,    !- Name
West Zone,               !- Zone Name
FlowFromSystem,          !- Air Flow Calculation Method
Watts/Area,              !- Design Power Input Calculation Method
,                        !- Watts per Unit {W}
,                        !- Number of Units
180,                     !- Watts per Zone Floor Area {W/m2}


My area is about 167m2 so when I use Output Facility Total Building Electric Demand Power to see the IT power in my model it approximately 47.9 kW instead of 30kW (= 180W*167m2) average per hour. This is my model.

Can someone tell me that where is different 17.9 kW (= 47.9 - 30) between 2 values? Or how we can calculate the Facility Total Building Electric Demand Power (and Facility Total HVAC Electric Demand Power) in EnergyPlus?

Thank all your support.

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1

@tri.ton99 can you add a screenshot of plots or other information to help explain your question? Are you referring to these kW values as outputs from specific timesteps over the simulation, or an annual report output?

The Air-Cooled IT Equipment object that represents the data center will have variable electricity use since the cooling power depends upon the computing power load and air temperature. It won't be constant 180 W/m2.

( 2021-05-30 17:53:47 -0500 )edit
1

Kind of similar to how rated COP/capacity is not the constant COP or capacity throughout the simulation because of performance curves, it looks like the Design Power Input is also not constant.

( 2021-07-01 13:08:28 -0500 )edit

Aaron Boranian I used outputs as:

Output:Variable,*,Facility Total Electric Demand Power,Hourly;

Output:Variable,*,Facility Total Building Electric Demand Power,Hourly;

Output:Variable,*,Facility Total HVAC Electric Demand Power,Hourly;

My HVAC system is the same as this question, the temperature I supplied for The Air-Cooled IT Equipment object was around 24 C.

( 2021-07-02 02:58:36 -0500 )edit