unmatched adjacencies and non planar surfaces

[byme_guy]

I have checked my model geometry and there are warnings about unmatched adjacencies and non-planar surfaces. How does the unmatched adjacencies and non planar surfaces affects the calculation? How can I avoid these problems?

Another thing is I have a model and I need to export it to another model using GEM export command. Before I exported it, I checked the model for intersections and it shows that there are none. When i try to import a gem file, there are a lot of warnings regarding intersecting rooms. How is this possible?

[PCully]

Hi,

To avoid these geometry problems you just have to take care when drawing the model and the most important piece of advice is snap end points to the grid! This way you can be sure that adjacent rooms will match and not have small discrepancies which often lead to these errors. Often it's worth forfeiting a little accuracy in terms of the real building for the sake of sticking to grid points and guaranteeing a robust model geometry.

The intersection errors when you import the GEM are more likely to be caused by the existing model geometry intersecting with the imported geometry. When you import it will be placed in the same coordinates as it was exported so try moving the existing geometry out the way before you import.
If you need to you can switch off the intersection check before importing (enter "int=off" in the ModelIT key-in), this way it won't complain about intersections but you will have to correct any intersections before you move on to analyses. Remember when you are finished you should switch the intersection check back on as it will help you (enter "int=on" in the ModelIT key-in).

Phil

[byme_guy]

Actually, the intersection warnings is within my GEM model and not with the existing model where working on since they have completely different elevations. Anyway, i think turning off the intersection will help me with importing the model. I'll try it first and give you feedback. With regards to ASHRAE loads, will unmatched adjacencies and non planar surface affects the calculation?

[PCully]

it's hard to say what affect geometry problems will have on thermal results, the Support team often just advise to fix as much as you can until the simulation runs without errors.

The main place we have seen recently where problems in the geometry can stop sims working is with the Suncast shading file as it is sensitive to the model so when it comes time to run apache simulations it rejects the shading file.

I'd always say work hard to fix any geometry issues like this as they come up and hopefully along the way you'll learn the modelling techniques and standards (grid) that help avoid them in the first place.

Phil

[luanaepb]

Hi,

I'm having the same kind of problem. I have a very simple building 30m x 40m with a central area oof 7mx7m. When I export the model from Sketchup to IES, there is no problem, no warnings. But when I check the model, there are warnings like " [00000000] "Room 001" - body intersects - 1: [00000001] "Room 002" and there are somme adjencies assign incorrectly ( some internal surfaces should be adjacent to a room but it's assign to exterior, there were doors created when there were no doors).

I don't know why this problems are happening with such a simple geometry. Do you have an idea?

Thank you.

[luanaepb]

Would it be due to the fact that the biggest room ( 30 x 40) is defined as an 8 vertice room because of the central room?

[PCully]

imports from SketchUp or any other 3rd party can be problematic at times as VE has less control of the source data.

First step I'd suggest you review the SketchUp model and clean it up, make sure all rooms are correctly drawn as bounded volumes and they are adjacent, make sure you don't have any extra lines (there are times in the past I've seen multiple lines drawn along the same edge and this can cause problems to the plug-in) and delete any extra vertices that aren't required. If you do all this and still find it imports with intersections then I'd suggest go back to SketchUp and define each room as a Group then use the IESVE toolbar Select Groups tool to define these as rooms (whole) and see if that improves things (you are then simplifying the model passed from SketchUp to VE).

I'm hopeful that your model isn't too big or complicated so you can try these suggestions without too much time expense.

Other ideas I have area really just to redraw problem rooms in ModelIT (delete them after import and then use the ModelIT tools), but try doing a rebuild first (see the ModelIT Settings menu >> Model... then click the Rebuild button to recalculate the adjacencies in the model.

Phil

[luanaepb]

Hi Phill,

I'll try your suggestions.

But why I found strange is that, for example, in ModelIT, when I try to create one central room inside a bigger one, there is the message: "space intersects the existing space".

So don't you think everyspace must be delimitated by 4 vertices intead of 8 (like the biggest room)?

Thank you.

[PCully]

Well vertices are created wherever two surfaces meet so if you have adjacent rooms that are not exactly aligned or are different sizes thenyou could have more vertices (if I understand you correctly?).

The "space intersects existing space" message you got is because you were trying to draw overlapping room volumes, this isn't allowed in ModelIT. In this room in a room scenario you are trying to draw you need to draw the outer room with the gap left for the inner room to be drawn after. Usually eaisest is to draw the outer room as multiple rooms (e.g. two C-shaped rooms would allow this).

This has probably been covered in more detqil on other posts on this forum (try searching "room in room", "Doughnut" or "donut")

Phil

[luanaepb]

Hi Phill,

I've already found this topics and I could find the answer. =)

Thank you!