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Dynamo Export Unit Conversion Query

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  • SHT6153
    Junior Member
    • March 14, 2017
    • 9

    Dynamo Export Unit Conversion Query

    Hi all,

    Have recently joined this forum, as I seek to learn more about Dynamo and how it can benefit my work in Revit. The main operation I am looking at right now is exporting information from Revit, to an Excel spreadsheet. I have created a basic graph for doing so and it works.

    My question is with the way that Dynamo converts the Metric units displayed in the Revit properties to Imperial and what units the Revit API uses. One of the properties I am testing in my exports is the Space Electrical Load, displayed in Watts. If I export 1W, the value displayed on the spreadsheet is 10.764 (rounded).

    Could I ask if anybody knows what the units for Watts are in the Revit API? The only conversion factor I have found for this number is ft2 to m2.

    Any help would be greatly appreciated,

    Thank you in advance.
  • amoursol
    Senior Member
    • November 21, 2012
    • 612
    • Boston, MA (USA)

    #2
    Hello!

    Dynamo is a unitless application. However, when opened from Revit, it will take the units from your current project file as default. So if you are pulling parameter data it will know what system that data resides within.

    To convert between unit types we can use the Core --> Units --> Convert Between Units node. You simply specify the input data type and the conversion factor.

    Bear in mind that area in Dynamo (If using metric) will come in as millimetres, so without using this node you would have to divide by 1,000,000 to get to metres.

    Sol Amour

    Architectural Explorer, Digital warrior, Affectual adventurer and Curious Human Being
    Portfolio Website @ Cargo Collective

    Comment

    • SHT6153
      Junior Member
      • March 14, 2017
      • 9

      #3
      Hi amoursol, thank you for your response!

      The issue I am having is that when bringing the units out, they are not the units that are presented within the Revit model. I have attached an image of my Dynamo graph and the corresponding space (please ignore all other details, it's a blank model for testing as I learn to use Dynamo). I have outlined the parameters that I have created in Revit and the corresponding outputs in Dynamo. The Supply Air parameter is read in cubic-foot-seconds (cfs) which, when exported, can be converted to l/s if required. However, I am unsure of what unit the Total Load is being converted to. The unit in Revit is Watts, but I cannot seem to see what it has been converted to. Would you happen to have any experience with this?

      Thank you again!
      Attached Files

      Comment

      • amoursol
        Senior Member
        • November 21, 2012
        • 612
        • Boston, MA (USA)

        #4
        I'm on the Architectural side rather than the Engineering so I'm afraid none of those units make much sense to me. It appears, with a quick test, that W/m³ is coming through correctly but L/s isn't. Could be a bug or could be correct - I have honestly no way of knowing. Might pay to ask the Dynamo developers or someone who is up with the play on the Mechanical side?

        If you use twitter, there are many helpful folk out there (Including the Dynamo team members themselves) that I can point you to. Otherwise, trying on the dynamo forums themselves may be better.

        Sol Amour

        Architectural Explorer, Digital warrior, Affectual adventurer and Curious Human Being
        Portfolio Website @ Cargo Collective

        Comment

        • josephpeel
          Forum Addict
          • May 3, 2012
          • 1416

          #5
          There is a package called "Get Parameter As Value String" that shows parameters using the display units, exactly as in the properties window. This does output a string not a number though so you may have to convert it back.
          You’ll probably get used to making the conversions in time, but if you don’t want to you can also use either of these 2 custom nodes from the ‘MEPover’ package: The GetParameterAsValueString node will return the values as strings though, so for calculation you’ll need to convert to a numeric type first. The GetParameterAsValueString will return the values as you see them in you Revit Interface.


          There is also some code that seems to convert any parameter from internal to UI units (I didnt test it yet). Which looks very useful.
          @Daniele_Teodori @Kulkul is right , AsValueString will get your aroud the unit conversion issues. Revit internally works with some units that can not be changed. You could also use the following code if you’d like to run conversions from/to the internal units: import clr clr.AddReference('RevitAPI') clr.AddReference('RevitServices') from RevitServices.Persistence import DocumentManager doc = DocumentManager.Instance.CurrentDBDocument #Getting Document UI Units - you nedd to precise the uni...


          I think the biggest issue is that some parameter tyoes are converted automatically (For example Length) and others (The non-architectural stuff..) isnt.
          Last edited by josephpeel; April 7, 2017, 08:19 AM.
          "One must imagine Sisyphus happy." Albert Camus - "The innovator has for enemies all those who have done well under the old conditions, and lukewarm defenders in those who may ​do well under the new." Nicolo Machiavelli -"Things that are too complex are not useful, Things that are useful are simple." Mikhail Kalashnikov

          Comment

          • josephpeel
            Forum Addict
            • May 3, 2012
            • 1416

            #6
            Originally posted by SHT6153
            The unit in Revit is Watts, but I cannot seem to see what it has been converted to.
            Ironically... its probably 'British Thermal Units per Second' which is 4/16th of a Trump/Minute.
            "One must imagine Sisyphus happy." Albert Camus - "The innovator has for enemies all those who have done well under the old conditions, and lukewarm defenders in those who may ​do well under the new." Nicolo Machiavelli -"Things that are too complex are not useful, Things that are useful are simple." Mikhail Kalashnikov

            Comment

            • amoursol
              Senior Member
              • November 21, 2012
              • 612
              • Boston, MA (USA)

              #7
              Originally posted by josephpeel
              Ironically... its probably 'British Thermal Units per Second' which is 4/16th of a Trump/Minute.
              Trump... Sheesh does that man dabble in everything?

              #LookedAtSixDegreesOfKevinBaconTheOtherDayAndFound OutTrumpWasntFarOff

              Sol Amour

              Architectural Explorer, Digital warrior, Affectual adventurer and Curious Human Being
              Portfolio Website @ Cargo Collective

              Comment

              • SHT6153
                Junior Member
                • March 14, 2017
                • 9

                #8
                Thanks all for the responses (I will avoid getting involved in the Trump discussion :P) Regarding the BTU/s, 1W is 0.00095 BTU/s. In the image posted above, 1W is coming out as 10.76.

                My only concern with using additional packages is ensuring that anybody who would use the graph would have the package installed. The current plan is to develop a spreadsheet that will have the conversion rates available to review the values as they are shown in Revit.

                Thanks again!

                Comment

                • amoursol
                  Senior Member
                  • November 21, 2012
                  • 612
                  • Boston, MA (USA)

                  #9
                  You can always hard-code the conversion if you so wish

                  Sol Amour

                  Architectural Explorer, Digital warrior, Affectual adventurer and Curious Human Being
                  Portfolio Website @ Cargo Collective

                  Comment

                  • SHT6153
                    Junior Member
                    • March 14, 2017
                    • 9

                    #10
                    May I please ask how I'd go about doing that? (excuse my distinct lack of experience here! :P )

                    Comment

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