Heating curve (weather compensation) in OpenStudio / EnergyPlus?

Is it possible to create a heating setpoint in Energyplus that is dependent on outside temperature?

I would like to model a baseboard heater system with an inlet temperature that is dependent on outside conditions. For higher outside temperatures, less heating capacity is needed. This means lower supply temperatures can be sufficient to meet heating demand.

Typically a curve would look like this. (inlet temperature vs. outdoor air) Heating curve

I have found SetpointManager:FollowOutdoorAirTemperature object, but that only follow the outdoor temperature. I would need a negative feedback.

Any thoughts on how one would implement such a system?

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LSurf

asked 2015-03-03 09:34:39 -0500

4.4k

__AmirRoth__

updated 2017-04-18 08:40:13 -0500

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@LSurf. Even though you mention E+ and OS in the heading of the question, it would not get emailed to E+ and OS subscribers unless you use the 'energyplus' and 'openstudio' tags. :)

__AmirRoth__ (2015-03-03 10:18:55 -0500) edit

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You can use a SetpointManager:OutdoorAirReset for this. The documentation makes it sound as though it's only available for air loops but it can be used for water loops too.

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Jamie Bull

answered 2015-03-03 10:35:49 -0500

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Perfect, exactly what I was looking for. In the documentation I indeed skipped the managers about Air, but didn't know they were applicable for PlantLoops as well.

LSurf (2015-03-04 02:09:31 -0500) edit

Same here. It was @Julien Marrec who suggested to me that it would also work for wet systems.

Jamie Bull (2015-03-04 02:18:19 -0500) edit

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This topic has some points you are looking for.

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Dinosaver

answered 2015-03-04 03:02:44 -0500

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As an alternative you can use EMS programs with IDF editor:

(1) in OpenStudio, define setpoint manager with constant temperature schedule [e.g.: controlledTemp], in preliminary scheme.

(2) in the generated out.idf insert an EMS sensor e.g. for outdoor drybulb temperature [sensor variable: OutdoorTemp]

(3) define actuator on the temperature schedule [controlledTemp] e.g.:

 myTempControl,              !- Name
    controlledTemp,          !- Actuated Component Unique Name
    Schedule:Constant,       !- Actuated Component Type
    Schedule Value;          !- Actuated Component Control Type

(4) Define heating curve by EMS program, e.g.

EnergyManagementSystem:Program,
myTempManager,                                              !- Name
SET controlledTemp=-32/40*OutdoorTemp+49,                   !- Program Line 1
IF controlledTemp>65,                                       !- Program Line 2
SET controlledTemp=65,                                      !- A4
ENDIF;                                                      !- A5

(5) Declare EMS program(s) to be run in EMS Program Calling Manager:

EnergyManagementSystem:ProgramCallingManager,
myEMS Custom Controls,                                        !- Name
EndOfZoneTimestepBeforeZoneReporting,                         !- EnergyPlus Model Calling Point
myTempManager,                                                !- Program Name 1

This solution is the most flexible because you have full control over setting limits and logical conditions. And, as the example shows, it is done quickly with a few instructions.