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How to set control strategies for plant loops?

asked 2015-05-27 18:41:13 -0500

Brian C gravatar image

updated 2017-05-17 12:40:27 -0500

I would like to be able to set basic control strategies for my water loops (i.e. CHW/HW resets, OAT lockouts, etc.)

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@Brian C Is this related to OpenStudio, EnergyPlus or both?

Neal Kruis gravatar image Neal Kruis  ( 2015-05-27 19:34:14 -0500 )edit

I would like to know how to do this within the OpenStudio app first. The Open Studio website says that they should be current features available...

Brian C gravatar image Brian C  ( 2015-05-28 10:37:37 -0500 )edit

@Neal Kruis I hope I used the @ symbol correctly...just checking in to see if you might be able to still help me regarding this question. Thanks!

Brian C gravatar image Brian C  ( 2015-05-29 13:14:41 -0500 )edit

@Kyle Benne might be better suited to answer this question.

Neal Kruis gravatar image Neal Kruis  ( 2015-05-29 14:29:37 -0500 )edit

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answered 2015-05-31 22:15:02 -0500

Plant loop control is generally handled by two categories of input objects in EnergyPlus and OpenStudio. Time of operation and component sequencing is handled by PlantEquipmentOperationScheme objects, while the actual plant supply temperature is dictated by setpoint managers. OpenStudio supports most of the setpoint managers that EnergyPlus offers including OA reset based SPM, scheduled setpoint, dual (hi / low) scheduled setpoint, follow OA temp, and several more. OpenStudio does not yet give you complete control over all of the available types of plant operation schemes, including one or two that would allow you to completely disable certain components under certain conditions or time of year. Those additional operation schemes will come in OpenStudio 1.9 this fall. For now OpenStudio generates heating and cooling load operation schemes for you depending on the type of component you have on the plant. Chillers and other cooling equipment will be put on a PlantEquipmentOperation:CoolingLoad, and boilers et al will go on the similar heating load object. In this scheme the components will available for all load ranges for all hours of the simulation. In OpenStudio if you place setpoint managers directly after the plant components, as opposed to only on the supply outlet node, OpenStudio will generate a component setpoint operation scheme like @aparker described here. Again you will have much more control over these operation schemes when 1.9 rolls out.

Another option is EMS. Sometimes the setpoint managers and operation schemes are not enough to get you exactly what you need. In that case you can write EMS logic to do just about anything you can dream up. In OpenStudio you would inject EMS code into you idf file using an EnergyPlus Measure.

This is a pretty short reply for such a large topic. Hopefully the links are enough to point you in the right direction, and perhaps others will reply with more information. If you post a narrative of a particular control scheme that you are trying to model, I think we can provide better guidance.

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We're hoping that support for EMS will be a big focus next year.

ljbrackney gravatar image ljbrackney  ( 2015-06-01 08:16:40 -0500 )edit

@Kyle Benne Thanks for the response. Utilizing the set-point managers and locating them at the plant component level answered my immediate question. One follow up question...with the OAT reset SPM, how does the associated schedule work? Should this be an ON/OFF schedule where if it is OFF then it will perform as defined in the Temperature 2 fields?

Brian C gravatar image Brian C  ( 2015-06-01 11:54:16 -0500 )edit

Not exactly ON/OFF. If used, the schedule should have a value of 1 or 2. If the value is 2 then the SPM will perform according to the Temperature 2 fields. I imagine this could be useful when the plant has a seasonal change over.

Kyle Benne gravatar image Kyle Benne  ( 2015-06-01 12:40:05 -0500 )edit

Has the feature discussed above (operation scheme control) been added to the most recent version of OpenStudio (1.12.0)? If so, I can't seem to find it. I'm looking to schedule a facility that has a hard, seasonal switch from a cooling tower to central chilled water and back once a year.

ethankheil gravatar image ethankheil  ( 2016-10-04 12:00:49 -0500 )edit

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Asked: 2015-05-27 18:41:13 -0500

Seen: 1,020 times

Last updated: May 31 '15