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Thread: Dynamo Export Unit Conversion Query

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    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.

  2. #2
    Senior Member amoursol's Avatar
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    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.
    KumarKapadia likes this.

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    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 Thumbnails Attached Thumbnails Dynamo Export Unit Conversion Query-dynamo-units-discussion.png  

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    Senior Member amoursol's Avatar
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    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.
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    Forum Addict josephpeel's Avatar
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    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.
    https://forum.dynamobim.com/t/space-...version/8952/8

    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.
    https://forum.dynamobim.com/t/proble...-values/6950/7

    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 7th, 2017 at 08:19 AM.
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    Forum Addict josephpeel's Avatar
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    Quote Originally Posted by SHT6153 View Post
    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.
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    Senior Member amoursol's Avatar
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    Quote Originally Posted by josephpeel View Post
    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
    Dave Jones likes this.

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    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!

  9. #9
    Senior Member amoursol's Avatar
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    You can always hard-code the conversion if you so wish

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

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