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    Heat Losses in Revit

    as we mainly use Revit for Co-ordination and scheduling purposes. I/we have never really delved into trying some of the other features revit has.

    Ie Heat losses, my boss has asked me to look into producing heat loss calcs from revit?!

    my question is, is it simple to set up and are the calculations reliable.

    and what is the process of doing it, is it about going about setting up the spaces correctly etc.. or is there more to it

    any help would be greatly appreciated

    N

    #2
    Yes... but I wouldnt describe it as simple and reliable. I guess just try and see.

    I do use spaces a lot for calculating stuff like ventilation rates though (Apply per m2/m3/person technical spec for different room types to the spaces so it remains updated with changes in the building), which is a good place to start with building calcs and design checks into your model.

    The problem I have with Revits heating calcs is that they are ASHRAE (I work in europe) and its also not entirely transparent what the program is doing. Trust in the results and how they are generated is the most important aspect of any simulation...
    Im considering trying to get all the wall areas for each space and calculate transmission losses using Dynamo, but thats quite far down the to do list.

    What do you currently use?
    Last edited by josephpeel; May 19, 2017, 02:21 PM.
    "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

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      #3
      Originally posted by josephpeel View Post
      Yes... but I wouldnt describe it as simple and reliable. I guess just try and see.

      I do use spaces a lot for calculating stuff like ventilation rates though (Apply per m2/m3/person technical spec for different room types to the spaces so it remains updated with changes in the building), which is a good place to start.

      The problem I have with Revits heating calcs is that they are ASHRAE (I work in europe) and its also not entirely transparent what the program is doing. Trust in the results and how they are generated is the most important aspect of any simulation...
      Im considering trying to get all the wall areas for each space and calculate transmission losses using Dynamo, but thats quite far down the to do list.
      Im in the UK, I did try a quick calc on 1 room and it seemed way out.

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        #4
        Ive had some success with exporting to other programs and reimporting the results, but its usually such a long round trip time we dont do it very often. Would be nice to have a calc in revit that updates easily
        "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

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          #5
          There was this;

          https://apps.autodesk.com/RVT/en/Det...en&os=Win32_64

          Looks interesting but not updated since 2014
          "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


            #6
            Originally posted by josephpeel View Post
            There was this;

            https://apps.autodesk.com/RVT/en/Det...en&os=Win32_64

            Looks interesting but not updated since 2014
            Should still work though shouldn't it based on that standard?

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              #7
              I'm a US user, but what I've taken to doing is using gbXML to export the space data to Carrier HAP. The envelope (wall, window and roof) data is garbage and can't be trusted (I'd love to see a concise explanation on how to get that to work quickly and reliably), but it WILL give you individual space entries with Area, Room Name/Number, lighting watts/sf, equipment heat gain, and occupancy already set up. (Assuming, of course, that you entered this into the Spaces inside of Revit.) From there, all you need to do is enter the envelope data, your schedules, and set up your System. The thing I like about HAP is that you can CTRL-C copy the table data from the Reports Preview and paste it into a spreadsheet with the tables intact. I don't think this was even an intended feature of HAP, but it works.

              If you want those heat loses in Revit, you'd enter them into each Spaces' Design Heating Load parameter. I plan on making a Dyanmo definition that will do this automatically, pulling the cooling air flow rate and heat load from the aforementioned spreadsheet and applying it to the correct Space parameters. From there, you can group your Spaces into HVAC Zones, and then sort/group your Space Schedule by Zone. Turn on the footer totals and voila, there's your total heat load for each terminal unit. In my case, I'll take that total and apply it to my Terminal Unit family, which plugs that heating load into a formula that sizes the heating coil automatically. I have a Dynamo script that will take that total Zone heat load and push it my Terminal Unit families automatically.

              Backing up a bit... it's important to set up your Spaces correctly, and I only recently figured this out. The first step is to create a Space in your MEP model for each Room in the linked Architectural model (which I was doing.) The next step (which is new for me) is to use Space Separator lines to carve up the larger Spaces into logical thermal zones (interior, exterior, etc.) Then use the Space Naming Utility, which will append each 'sub-space' with a -1, -2, -3 suffix. Then, you group the Spaces into HVAC Zones that will represent your intended Terminal Unit zoning. The nice thing is that you can then use a Color Legend to generate a colorful zoning diagram to show to your manager. Get him to agree to the zoning (lots of managers are picky about this), incorporate his changes, and THEN do the gbXML export that I described above. This is a very nice "workflow" thing that will prevent the "why did you zone it this way? Change it" discussion after you've modeled your ductwork.

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                #8
                Originally posted by Necro99 View Post
                The next step (which is new for me) is to use Space Separator lines to carve up the larger Spaces into logical thermal zones (interior, exterior, etc.) Then use the Space Naming Utility, which will append each 'sub-space' with a -1, -2, -3 suffix.
                How do you deal with showing location of equipment when your spaces have appended numbers? Do you just live with it, or do you change them back to having no appendages?

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                  #9
                  The Space Name and Space Number have the -1, -2, etc. added the them. The Room Name and Number are in the Architectural Link and are unchanged, but can still be reported by your Space Schedule and Space Tags, or by any schedule for which "Room" is an option in the Schedule Properties > Fields > "Select Available fields from" pulldown menu.

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                    #10
                    I didn't know that existed....However, I can't see the space:room name/number field when i'm making an equipment schedule, which is the concern that some of the people at my company have (having the -1,-2,etc). And unless you have magic powers, equipment can't be location aware through links.

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