Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Measure to change the Design Flow Rate Calculation Method in OpenStudio

asked 2015-08-11 09:24:15 -0500

Alec's avatar

updated 2017-08-05 13:12:08 -0500

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?

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted

answered 2015-08-11 09:58:39 -0500

updated 2015-08-11 09:59:28 -0500

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.

edit flag offensive delete link more


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

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

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Training Workshops

Question Tools

1 follower


Asked: 2015-08-11 09:24:15 -0500

Seen: 294 times

Last updated: Aug 11 '15