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Switching the master and slave zones

asked 2021-08-12 10:46:21 -0500

Melina's avatar

updated 2021-08-12 11:11:13 -0500

Hi everyone. I have 2 zones in a building and my HVAC system is all air. I have defined a furnace for heating and cooling coil which consumes electricity. I also have defined AirloopHVAC:Unitary:Furnace:HeatCool and in this part I have to choose my controlled (master) zone. I don't want to choose one because the master zone is a variable in my case which depends on time. I mean my problem is that I want to write a code so the master and slave zone can be switched alternatively (based on occupancy which is determined base on a constant schedule)

I'm new to Energyplus and recently I've got that I can use EMS but I cannot understand what should I put in Field: Output:Variable or Output:Meter Index Key Name part or Field: Output:Variable or Output:Meter Name. The examples of EP version 9.5 that have EMS didn't help me. I want to know what is the Index Key Name in this problem that I explained.

And I don't know what is the Field: Actuated Component Unique Name in my case in EnergyManagementSystem:Actuator part.

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answered 2021-08-16 21:43:50 -0500

mechyai's avatar

This is a random exerpt from an IDF file I am working on with Python EMS. You can see there are two objects, Output:Meter and Output:Variable.

The meter name is "ElectricityNet:Facility", and the variable key and name is "*" and "Zone People Occupant Count", respectively. The "*" just means that I need to specify a certain Zone name as the "*" represents all possible inputs (Zones) for that field. This is all I need to access those output data.

image description

And this post may help with the actuators.

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Thank you but I have 2 zones, How can I define which Zone's occupancy I need in the sensor? Can I use the zone's name instead of "*"??

Melina's avatar Melina  ( 2021-08-16 22:00:36 -0500 )edit

@Melina, Yes. But your available output variables, meters, EMS sesnors, and EMS actuators depends on your IDF model. Your .rdd, .mdd, .edd output files will show you all your available outputs.

mechyai's avatar mechyai  ( 2021-08-17 07:43:33 -0500 )edit

Thank you very much. I did that and now I have a very simple problem! I've written a simple program with if and it says IF the DayOfWeek is Monday(DayOfWeek==2) or Tuesday(DayOfWeek==3) then SET the airflow of this zone== A Number ... and then ENDIF But as a result, we see that if the software once enters the loop and the condition is satisfied, it never comes out! I mean from the first Monday that I have in my simulation days until the last day of it (365 days), it sets the airflow equal to that number!!! Do have any idea where the problem is?!

Melina's avatar Melina  ( 2021-08-17 09:44:36 -0500 )edit

You need to use "ELSE Set airflow=NULL". See the EMS Actuator documentation where it says: "Actuators override things inside EnergyPlus whenever the actuator’s Erl variable is set to a value other than “Null.” Null is a special built-in variable used to deactivate an actuator. Once an actuator starts overriding, it will continue to do so until the actuator’s Erl variable is set to Null. You should set the actuators to Null whenever you want the EMS to revert to normal operation."

shorowit's avatar shorowit  ( 2021-08-17 10:00:16 -0500 )edit

Thank you very much! my problem is solved!

Melina's avatar Melina  ( 2021-08-17 10:11:30 -0500 )edit

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Asked: 2021-08-12 10:46:21 -0500

Seen: 113 times

Last updated: Aug 16 '21