Sketchup-OpenStudio Plugin: "Create Spaces From Diagram" option concern

asked 2021-08-04 10:43:48 -0500

I have a concern about which way is the correct way to approach. I am considering the following 2 pics to make my concern clear to you. Considering a 2 story building as shown in pics, there are spaces that continue up to the 2 story roof without dividing from a slab or 1st level ceiling. For example, the lobby of an office or living room of a house can extend to the roof from the ground.

In Pic 1, I have achieved this by using the "Create Spaces From Diagram" option, and the whole building is erected as a 10' high 2 story building and then deleting the ceiling surface of the lobby space on the first floor and then deleting the floor surface of the second story lobby space.

In Pic 2, I have achieved this by using the same "Create Spaces From Diagram" option for the lobby as 20' high 1 story and for the rest of the spaces 10' high 2 stories as usual.

In Pic 1 same lobby is identified as 2 spaces and 2 stories while in pic 2 lobby is recognized as 1 single-story, the lower partition area as the 2nd story, and the upper partitions as the 3rd story. In the 2nd pic example, it recognizes the building consists of 3 stories even though actually it is 2 stories.

My concern is which way is the correct way to approach when needing to run an energy simulation using OpensStudio? Your insight is greatly appreciated.

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answered 2021-08-05 00:11:55 -0500

David Goldwasser

20295 ●94 ●14 http://www.openstudio.net/

Deleting the surfaces in Pic 1 is no ta good idea and can produce unpredictable results for the floor area and volume. I would suggest instead of deleting the surfaces between the spaces to use an air wall construction, and to make sure both spaces are assigned to the same EnergyPlus thermal zone. OpenStudio should not include the floor area of the mid-atrium air wall in calculating internal loads per floor area, and OpenStudio will form a zone that looks very similar to picture 2.

Neither of these approaches (if you use advice for spaces in same zone) address vertical temperature stratification within the double height space.

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David, could you kindly show me how to construct an air wall. Sorry, not an expert in SketchUp-Openstudio. And your insight is greatly appreciated. Thanks.

nissaldeelaka ( 2021-08-05 10:49:30 -0500 )edit

Go to the constructions tab and download it from the BCL?

https://bcl.nrel.gov/

I came across this measure, but I don't think it applies to your use case because you are dealing with an air wall boundary that is a ceiling/floor, rather than a wall.

https://bcl.nrel.gov/node/83273

"Zone mixing will only be added where there is an air wall and where the matched surfaces belong to spaces in different thermal zones and the base surface type is a wall. Currently floors are not addressed by this measure."

sashadf1 ( 2021-08-05 17:21:50 -0500 )edit

Oh okay, I'll try thank you.

nissaldeelaka ( 2021-08-05 20:58:01 -0500 )edit

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answered 2021-08-04 11:33:20 -0500

obuchely

1378 ●13 ●13

I think both approaches are correct. The results should be similar when you run the simulation. In the first pic you have double high walls divided per floor. If you are doing comfort analysis the radiant temperature could be different. If you have a split wall each wall may have a different temperature if you have adjacent buildings or something that can cause shading in parts of the wall.