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How to include thermal bridges in the analysis in the OpenStudio - EnergyPlus?

asked 2014-12-07 11:44:11 -0600

updated 2015-07-10 21:14:41 -0600

How to include in the analysis thermal bridges due to columns, beams, overhangs, etc in the OpenStudio - EnergyPlus?

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@Pithon - what software are you using? For EnergyPlus/OpenStudio please refer to this answered question.

MatthewSteen gravatar imageMatthewSteen ( 2014-12-07 16:43:33 -0600 )edit

Thank's Matthew. I edited my question and the flags.

Geraldo Pithon gravatar imageGeraldo Pithon ( 2014-12-20 14:08:11 -0600 )edit

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answered 2014-12-23 02:13:56 -0600

Thermal bridges can be introduced in OpenStudio or Energy plus using small sub-surface with the same thermal transmission than the thermal bridge. You need to calculate the thermal bridge using other tool (ie Therm), and then you can use one construction with a no mass material in order to introduce the thermal transmission due to thermal bridge.

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Interesting idea, using a small surface. I usually calculate a modified overall R-value including the thermal bridge using Therm, and use that for the wall as a whole. Isn't your method very tedious though? (I already tend to get very frustrated with the sketchup plugin for simple geometry, but maybe it's just me)

Also, I'm not that familiar with how E+ does the actual thermal loss computation for the envelope. Can you comment on whether your method improves or not the accuracy?

Julien Marrec gravatar imageJulien Marrec ( 2014-12-23 03:36:52 -0600 )edit

It's true when exist a lot of thermal bridges is a little bit tedious to put all in the sketchup pluguin. I believe is the best way to introduce thermal birdges otherwise the thermal capacity of the envelope will be modified. If you modify the "construction" in order to include thermal bridges effect it's also tedious because you need to "adapt" constructions in each surface. If you want you can "group" all thermal biridges in each zone as only one (some recalculatios sohould be needed)

josepsolebonet@telefonica.net gravatar imagejosepsolebonet@telefonica.net ( 2014-12-23 05:02:44 -0600 )edit
4

I am not sure which option is best because introducing those subsurfaces without thermal mass only represents the steady state behaviour of the bridge. However, degrading thermal insulation for the whole construction is also including thermal capacitance for the bridge (which will not be the same as the base construction but certainly it will not be zero either). Unfortunately there is not a totally suitable method to represent thermal briges in whole building dynamic simulation so we have to live with this sort of approximations.

ecoeficiente gravatar imageecoeficiente ( 2015-01-03 04:38:10 -0600 )edit
4

answered 2014-12-08 09:52:51 -0600

BC Hydro has a published the Building Envelope Thermal Bridging Guide that is a very comprehensive guide to modeling thermal bridging in buildings.

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Dear aparker,

Thank's for your help!

I visited the site and it is really interesting, but I need more time to read the manual calmly.

I thought there was some way of inserting thermal bridges directly in OpenStudio given its great influence. But I have studied and I think the only way to do this is through CompositeWallConstructions. I need to read the manual to understand how to proceed with these components.

I will study the link documents in the link you sent.

Thanks!

Geraldo Pithon gravatar imageGeraldo Pithon ( 2014-12-20 14:57:38 -0600 )edit

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Asked: 2014-12-07 11:44:11 -0600

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Last updated: Dec 23 '14