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Measure to change the Design Flow Rate Calculation Method in OpenStudio

I am trying to write an OS measure to change the Air Changes/Hour for all spaces within a space type to a set value. The measure works as long as the Design Flow Rate Calculation Method is set to "AirChanges/Hour"; however, it does not work if the calculation method is set to a different value. I want the measure to first set the Design Flow Rate Calculation Method to "AirChanges/Hour" for the space type before attempting to set the value, but I can't figure out how to do this using the measure writing guide and SDK Documentation. There appears to be methods to return the Design Flow Rate Calculation Method, but not to set it. I have found an EnergyPlus measure that changes the calculation method, but I want to execute the measure in OS. What code can I use in a measure to set the Design Flow Rate Calculation Method for a space type in OS?

Alec's avatar
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Alec
asked 2015-08-11 09:24:15 -0500
__AmirRoth__'s avatar
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__AmirRoth__
updated 2017-08-05 13:12:08 -0500
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There are 5 methods to set the infiltration rate for the SpaceInfiltrationDesignFlowRate object. I believe that setting a values will change the 'designFlowRateCalculationMethod' to the appropriate value. Try looking at the value in your resulting model, or use an info statement in the measure to report the calculation method after you set the ACH.

  • setDesignFlowRate()
  • setFlowperSpaceFloorArea()
  • setFlowperExteriorSurfaceArea()
  • setFlowperExteriorWallArea()
  • setAirChangesperHour()

Note that in the GUI ExteriorSurfaceArea and ExteriorWallArea display the value in the same field, but have unique calculation methods.

David Goldwasser's avatar
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David Goldwasser
answered 2015-08-11 09:58:39 -0500, updated 2015-08-11 09:59:28 -0500
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David, thank you for your reply. I was setting all other design flow rates to 0.0, but was doing it after I set the Air Changes per Hour to the new value. When I changed the order of operation to set the other flow rates to 0.0 before changing the Air Changes per Hour, it worked. I'm guessing the order matters because it wouldn't allow me to change the Air Change per Hour until I zeroed out the other values and OS changed the calculation method automatically.

Alec's avatar Alec (2015-08-11 10:14:59 -0500) edit
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You can probably skip zero-ing out the other values. If it isn't using that calc method it won't matter if it has a non-zero value (api may zero the other values, I don't think it does but it might?)

David Goldwasser's avatar David Goldwasser (2015-08-11 10:54:14 -0500) edit
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