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how to model Window with the right Uvalue in equest

asked 2021-10-20 17:52:25 -0600

khalil chebl's avatar

updated 2022-02-21 20:41:41 -0600

I want to ask how to model a window with known U value from Glass library in equest ? The problem that when i choose a glass type and the width of the frame (0.11ft) i don't get the right Uvalue in the report that match with Glass library. I read Somewhere that when i choose a class type from the library i must set the frame width to 0 i don't know if this the right way to do it

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answered 2021-11-03 18:47:41 -0600

khalil chebl's avatar

Thanks for your response I tried to double clear glass (2004) with a frame of aluminum with thermal brake : U-value(glass only)= 0.48 Btu/hft2°F and NRFC U-value=0.57 Btu/hft2°F the problem that I get a window conductance value=1.47 Btu/hft2°F. Even when i change the frame width or conductance nothing change

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When I run a glass type 2004 with a thermally broken frame (eQUEST entered frame conductance U-value of 1.245 BTU/hr-ft2-F) with an NFRC size (48" by 59" fixed) I get a U-value of 0.568. I cannot replicate your results. Where are you looking for the window conductance -- in the LV-D report?

bfountain's avatar bfountain  ( 2021-11-06 11:17:03 -0600 )edit

in the spreadsheet of the glass Type it is always 1.47 Btu/hft2°F no matter what type of glass I choose

khalil chebl's avatar khalil chebl  ( 2021-11-06 11:33:03 -0600 )edit

answered 2021-10-23 07:16:15 -0600

bfountain's avatar

If you are modelling glazing using an entry from the glass library then you do indeed have to also enter a frame width and frame conduction. The glass library parameters are only for the glass portion of the window, not the frame. If your overall U-value is not as expected, I would first check your frame conduction value. Also note that the spreadsheet showing a U-value is for a standard window size. Larger windows will have proportionally less edge and frame effect so lower U-value. Smaller windows have higher U-values due to dominating edge and frame impact.

Conversely, if you use the simplified method for glass type definition then you enter the whole assembly U-value (NFRC u-value) including the frame and then set your frame width to 0.

The advantage of using the glass library is that the solar impact at different sun angles is more correct as there is a curve for solar as a function of sun angle.

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Asked: 2021-10-20 17:52:25 -0600

Seen: 177 times

Last updated: Oct 23 '21