Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question
5

After intersecting the entire model and surface matching, only a few spaces interior spaces show up green. What's going on?

asked 2014-11-10 13:43:21 -0500

poloplaya gravatar image

updated 2014-11-10 14:55:50 -0500

I am using SketchUp 8 and OpenStudio 1.3.4.

edit retag flag offensive close merge delete

3 Answers

Sort by ยป oldest newest most voted
5

answered 2014-11-10 14:27:53 -0500

This often happens when the original geometry has been imported from other cad tools into SketchUp. The surface matching looks for exact matches in geometry. The intersect tool expects the surfaces to be in the same plane, but if they are offset by even a small amount it may not find an intersection. In the first two images below I moved the south east (relative) cube a fraction of an inch before doing surface matching. As a result it didn't match. There are two approaches for a solution.

  1. Ideal solution - it would be nice to keep your model clean and get the geometry in the precise position. Then you can re-run surface matching.
  2. It isn't always easy to fix this geometry, so another alternative is to manually match the surfaces using the OpenStudio inspector. First select one of the two surfaces you want to match, select it and make note of the surface name. Next select to the surface you want to match it to. Once selected go to the "Outside Boundary Condition Object" and then refer to the name of the other surface. This result in the boundary condition of both surfaces being changed to "Surface" and they will refer to each other. If you want to un-match this, then go back to the "Outside Boundary Condition Object" and clear out the surface. Note that you can't manually switch a surface to or from "Surface" boundary condition using the "Outside Boundary Condition" field.

image description This shows my example problem model. I used a section cut to inspect it for issues while in render by boundary condition. You can select and push the section cut through the building to look at hidden spaces.

image description Another nice way to inspect for issues is to use the surface search for surfaces with boundary condition of "Surface" to hide the outside skin of the building. You can also search for "Outdoors" if you only want to see the skin. Add a section cut to this search and it is very powerful.

image description I rotated the problem surface out just for the demonstration, you of course don't want to do this. This is just to show what the the surfaces look like and what the inspector shows to start with.

image description Compare the inspector to the image above. This is how you would force a surface match even if the OpenStudio plugin didn't find it when using the automated tool. A lot of people get caught up trying to manually change the "Outside Boundary Condition" field instead of the "Outside Boundary Condition Object" field. Note: if you are using the legacy plugin you can directly change the "Outside Boundary Condition" field, but you will also have to hand connect the surface pair as well.

edit flag offensive delete link more

Comments

if we have a space seperated in 2 rooms by a wall can we use as an ''Outside Boundary Condition Object'' the wall itself?

alex pap gravatar imagealex pap ( 2016-04-05 09:13:21 -0500 )edit

I would either make two separate spaces that share the wall, or model the wall as an interior partition. The space surfaces should make a clean empty volume with new interior surfaces.

David Goldwasser gravatar imageDavid Goldwasser ( 2016-04-05 11:15:07 -0500 )edit

ok! thank you! one more thing, if i model the wall as an interior partition can i assign properties to it, like thickness, i want to draw some stairs and an elevator. i 'm not even sure if i have to draw them, i guess not. what do u think?

alex pap gravatar imagealex pap ( 2016-04-05 16:26:49 -0500 )edit

I would not draw them unless they are critical for a daylighting analysis using Radiance. You can add internal mass to a space without drawing geometry for it. Also while the construction of an interior partition has a thickness for thermal analysis, what is used for Radiance is just a thin wall. So you could draw multiple partitions to mimic wall thickness for daylighting analysis. If you aren't using Radiance then the position of internal mass objects within a space doesn't matter..

David Goldwasser gravatar imageDavid Goldwasser ( 2016-04-07 09:58:18 -0500 )edit

i 'm going to use energy plus so i m more interesed in the thermal part. i think i will just draw them as interior partitions. thanks a lot!!

alex pap gravatar imagealex pap ( 2016-04-09 05:48:54 -0500 )edit
3

answered 2014-11-10 14:23:51 -0500

updated 2014-11-10 14:54:52 -0500

A search through the sketchup tagged questions show the links below. I will add that it's important to make sure you draw your model carefully and cleanly - i.e. making sure that there are no stray marks and that adjacent lines/surfaces are in fact touching.

https://unmethours.com/question/666/h...

https://unmethours.com/question/909/s...

https://unmethours.com/question/996/c...

edit flag offensive delete link more
1

answered 2014-11-10 13:52:56 -0500

updated 2014-11-10 13:58:06 -0500

Sometimes I have this same problem and some surfaces doesn't match because I'm using some complex geometry on the model, you could use the Open Studio Inspector Tool (is like a magnificent glass whit a cube inside) to match the surfaces that you need, it could take some time but makes the job done :D.

Julian.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

1 follower

Stats

Asked: 2014-11-10 13:43:21 -0500

Seen: 2,209 times

Last updated: Oct 14