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"Increase R-value of insulation" PAT measure problem

asked 2023-03-29 15:47:59 -0500

Georgios_Ster's avatar

updated 2023-03-30 09:27:35 -0500

Hello everyone,

I am new to OpenStudio and I have just started experimenting with the PAT tool. I have encountered a problem with the measure "Increase R-value of Insulation for Exterior Walls to a Specific Value". Whenever I use values of R greater than 25, I receive a "completed fail" error. The Energy Plus report states that the "material is too thick for CTF calculation" in one case and that the material is "very thin, highly conductive" in the other case, which is not true.

In the initial model, the walls do not have insulation and are made of two rows of bricks, each 9 cm thick covered with lime plaster. When I examined the osm file generated from PAT with R-value equal to R25, I found that in the "constructions" tab, the measure tries to increase the thickness of the brick up to 1.8m to achieve the required R value of 25. So, I thought that if the measure works this way (trying to increase the 2nd construction layer to achieve the required R-value), I could add an insulating material with a thickness of approximately 0cm to the initial model. However, when I did this, the measure did not add any insulation at all, and all the results were the same as the initial model. Also, in both aforementioned cases, I did not get any results under the Reports tab in the Summary table.

Is there a way to fix this problem? Am I missing something?

Thank you very much.

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Thank you so much for your answer it solved the problem but I still did not get any results under the Reports tab in the Summary table. Also, what about the costs that are imported into the measure? Is there a way to do a cost - benefit analysis and choose the optimum insulation?

Georgios_Ster's avatar Georgios_Ster  ( 2023-04-01 13:46:36 -0500 )edit

"did not get any results under the Reports tab in the Summary table". Can't help you with PAT feedback. In an attempt to isolate the issue, run the same model + measure in the OpenStudio App. What runner feedback are you seeing when you "run" the simulation? I just ran the measure on a random OSM (e.g. R30 for wall insulation): it succeeded, provided plenty of feedback just before running the E+ simulation, generated the IDF as expected.

Denis Bourgeois's avatar Denis Bourgeois  ( 2023-04-03 13:49:53 -0500 )edit

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answered 2023-04-13 09:44:57 -0500

(an answer, previously an initial comment on March 30)

The measure is seeking an "insulating layer" to adjust, i.e. a layer in the construction offering the greatest R-value. As such, the measure ignores a 0mm layer. Ensure the added material initially offers more thermal resistance than the others, e.g. LAYER 2:

 - LAYER 1: brick (89mm, RSI 0.12)
 - LAYER 2: XPS (10mm, RSI 0.42)
 - LAYER 3: brick (89mm, RSI 0.12)
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Asked: 2023-03-29 15:47:59 -0500

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Last updated: Apr 14 '23