Using LBNL WINDOW to create custom glass types

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Tip-of-the-month: Creating custom glass types using the latest WINDOW software.
The Window Manufacturers Window Library that comes with eQUEST is now 12 years old. Today's Zero-Energy and Passive House projects have window assembly performance outside the available range of library selections. eQUEST has a built-in tool for importing glass type data. I have finally figured out how to use it! Here's the process I followed:

1. Download and install WINDOW. The built-in eQUEST library glass types were created in WINDOW 5.2. I installed 7.6.04 instead of the newest beta version.
2. Watch the Glazing System tutorial and the Window with Generic Frame tutorial (in that order) and download other documentation at
3. Open WINDOW. Respond to the Update Manager which pops-up automatically. (I updated the International Glazing Database (IGDB) to version 63.)
4. Watch the tutorials in Step 2 and follow along.
5. Create a new glazing system per the tutorial. When you "Calc", the results show you the COG U-factor, the VLT(Tvis) and the SHGC/SC for the glazing only (no frame effects included).
6. Create a new window per the tutorial, using the glazing system. Note: I don't think it matters what you select for the frame type as long as you use one of the first four which are standard ASHRAE frames. You input the actual frame properties within eQUEST.
7. Save and Calc the window.
8. Click "Report" and select "DOE-2" report type. (DOE-2 is not a Report type option from the Glazing System Library. You have to be within the Window Library.)
9. Save the .txt file in the Window folder within the eQUEST Data folder. (Such as Documents -> eQUEST 3-65-7175 Data -> Window)
10. Open the file with a text editor. EDIT THE FIRST LINE. The file will not import properly into eQUEST if the first line starts with "BERKELEY LAB WINDOW v7.6.4.0". I don't know which part causes the error but it will work if you change the first line to:

Window 5.2 v5.2.12 DOE-2 Data File : Multi Band Calculation

1. Save the edited .txt file.
2. Open an eQUEST model to use the new glass type.
3. Go to Tools -> Import Window4/5 Report File... and select the file you saved in step 11.
4. eQUEST asks if you want to Reevaluate all components. Sure. Go crazy.
5. A new Glass Type Code is created, and a new Glass Type which uses the new G-T-C.

I believe the above process will work with any recent eQUEST version running either DOE-2.2 or DOE-2.3 but I've only tried it in build 7175, DOE-2.3.
The FRAME-WIDTH, FRAME-CONDUCT and SPACER-TYPE will all alter the performance of a WINDOW in eQUEST/DOE-2. See the LV-D and LV-H reports to see the impact of the new glass type and frame properties. The spacer type impacts window performance (as verified by BEPS/BEPU), but the change doesn't seem to appear in the LV-D and LV-H reports.
I am still learning the WINDOW software and have not tried THERM or the other LBNL software that interacts with it.

Yes, you can use the "Simplified" method to define the glass type (TYPE = SHADING-COEF), which allows you to use any values you want for shading coefficient, glass conductance, visible transmittance and outside emissivity. This gives less accurate solar heat gains, especially with multipane and/or coated windows, and the conductance does not vary with inside-to-outside temperature difference.

Have fun and pay it forward!

William Bishop, PE, BEMP, BEAP, CEM, LEED AP
Senior Energy Engineer

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Bill Bishop's picture
Joined: 2012-02-25
Reputation: 7

Re: step 10 about editing the first line of the .txt file.

I've found that it was text "BERKELEY LAB" that was causing eQUEST to crash when importing the glass type (see BAD and GOOD images below). Not sure when LBNL decided to add that text to the WINDOW exports but it used to work just fine without any manual editing of the text.

[cid:image003.png at 01D492DD.E6335AE0]

GOOD (make sure to remove any spaces before "WINDOW"):
[cid:image004.png at 01D492DD.E6335AE0]


Michael Weller
Senior Energy Analyst

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Weller, Michael's picture
Joined: 2018-12-14
Reputation: 0

Thanks for this summary Bill!

On this topic, over the past few years we've run into a few bugs with
the WINDOW -> eQUEST import.

* In eQ v3.63 and 3.64, the import of WINDOW data neglected to
populate the FILM-CONDS keyword when creating the custom
GLASS-TYPE-CODE (G-T-C).? This resulted in much lower U_cog values
than expected. We tested import with v3.65 and this bug appears to
have been fixed.
* If used for switchable glazing, the GLASS-TYPEs referenced by WINDOW
objects must be listed in the input file in consecutive order.?
Otherwise, a BDL error will result. Not sure if this has been fixed
in v3.65
* If used for switchable glazing, the G-T-Cs used must have an numeric
integer name that is >1000.? Otherwise, a BDL error will result. Not
sure if this has been fixed in v3.65

- David

David Reddy4's picture
Joined: 2012-03-30
Reputation: 0