Forums >> Revit Systems >> Technical Support >> Roofs and ceilings in Analytical Surfaces

Gyvven

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Joined: Wed, Dec 19, 2007
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I ran the Heating and Cooling Loads calc on my model and noticed that some of my roofs were not being calculated. When looking at the Analytical Surfaces for each space I noticed the the spaces that calculated the loads properly were showing roof surfaces for both the plenum space and the room (there are no ceiling surfaces for either space). However, when I looked at the spaces that weren't calculating properly I saw that both the plenum and room were showing ceiling and roof surfaces.

When I created the spaces and plenums I used exactly the same settings and only changed the room type after the spaces were finished.

As you can see in my screenshot the space 241 PACKET OFFICE and it's plenum 479 Space only show Roofs, and this calculates properly. But 246 CONFERENCE ROOM and 480 Space have Ceilings and don't.

I'd appreciate any insight you can provide.

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Gyvven

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Joined: Wed, Dec 19, 2007
69 Posts

It seems I'm having an issue attaching my jpg. It's only 107Kb, so it shouldn't have any problems.

I'll try it again. If it doesn't work could one of the admins give me a hand?

Thanks

Edited on: Tue, May 31, 2011 at 11:04:12 AM

Still not able to attach file.

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thetabest

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Joined: Tue, Mar 15, 2011
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Just a farfetched thought, but perhaps this might be it.  My understanding is that Revit wants spaces "Everywhere", so even in your column wraps, or void spaces between walls... Thus, if your space is fully enclosed by a ceiling, then there should be an additional space in the plennum... I'd try placing one as such, then seeing if your numbers come out closer to what you expected.  The other thing is making sure that your spaces have the plennum or occupied check boxes checked appropriately...  For anything additional, we have to wait on that screenshot, and since that function is apparently dead today, post it later once it is working again...

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Trent Best

Best Systems

the.tabest@gmail.com

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Gyvven

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Joined: Wed, Dec 19, 2007
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Thanks for your input Trent. I don't think it's anything to do with spaces for void spaces as the rooms that aren't working similarly are adjacent to each other and neither space/zone has a void/column wrap/plumbing chase. Here's my workflow:

1) Since Arch didn't have a model ready at the time I used their 2d cad work to create generic walls.

2) I made sure all walls had the proper function, interior or exterior.

3) Created a ceiling for every space (same type, same height for all rooms).

4) Created a single flat roof, no slopes.

5) Linked this into my Mech model and dropped in all my spaces.

6) Verified Building construction components and U values.

7) Adjusted all spaces to appropriate type (ie. from <BUILDING> to Office or Restroom.)

Verified Occupancy for each space.

9) I added a plenum level and added plenum spaces above each room.

10) Created zones for my VAVs by including all spaces and plenums for each.

11) I made my logical systems for each VAV as well, though not needed at this point.

12) Ran the load calculator and began reviewing and noticed several zones not reporting roof loads.

AFAIK this is how the workflow should go. I've selected all the plenum spaces to verify they were identical, did the same for all the room spaces for floor and ceiling levels.  My upper offset on the rooms is set to First Level 9'-0" not as the plenum level (which is at 9'-0" aff). I'm going to try changing that to see if it'll effect anything.

I'm also going to try making all the spaces the same type and see if that changes anything. I doubt it, but it's something to try.

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thetabest

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Sounds correct, and frustrating, I'm assuming no design options, or any other more complex functionality going on?  Design options will only show the base footprint with regards to spaces, etc.  And as to its something to Try, that is the craziest aspect of this program, seems that sometimes, something that you wouldn't think was related, ends up fixing the problem, so definitely try away.  If I was in your shoes, I'd be closely looking at the ones that worked, vs the ones that don't to figure out why they are different, then build a test project to verify your findings, and establish any issues that stem from your process.  Finally, I'd consider whether or not you have support, sending this one to them for answers.

Please let us know more info as it becomes available, or a solution should you get one.

GL

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Trent Best

Best Systems

the.tabest@gmail.com

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Gyvven

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Joined: Wed, Dec 19, 2007
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Funny, THIS is the test and I AM the support. Unlesss you were speaking of our software supplier.

On another, nearly identical project I was able to run the calcs and figure out what needed to be in place before the numbers would be close to the numbers we got from Trace. This project was going to be our full Revit test project with Trace to verify the calculations. The only two issues I've had prior to this were with Window Loads and Ventilation. Window Loads are between 5 and 10 times higher than the Trace numbers, and with Ventilation we can't select an ASHRAE 62.1 computing model, so we need to fudge the CFM/SF numbers for each space. We're still using 2011 but waiting for the-powers-that-be to let us install 2012 so I can play with it.

I've been using Revit for 5+ years, but only using MEP for the past 5 months. It's a completely different animal, both more and less complex than Revit Arch, yet the basics are the same.

If I find a solution I'll post it up here. I'm sure it'll be something really simple, it usually is. (Don't you just hate it when you post a question and then find the really easy answer 5 minutes later?)

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Gyvven

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Update:

In my quest to find the solution as to why some zones calculate roofs and some not I've managed to break the ones that had roofs.

I was playing with the offsets for the spaces and thought I'd try pushing the room space offsets to the roof level. I think this is when it broke, and bringing all the space offsets, both room and plenum, back to the base and upper levels with no offsets has not fixed the issue. It is now well and truly horked.

I'll create a new file from scratch and see if I can replicate this problem. If I can keep it small enough I'll upload it and hopefully someone will be able to tell me where my problem lies.

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Gyvven

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UPDATE: PROBLEM SOLVED! ...sort of.

I remembered that since Revit views any bounding element with a space on only one side as being Exterior I could remove my plenum spaces and it should read my roof loads. This worked, however, this has the effect of removing the plenum volume from the calcs, which is fine for my purposes since we are using direct return.

I'd still like to figure out why the calcs wouldn't pick up the roof loads when I have plenum spaces.

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