[BLDG-SIM] EQuest question: glass conductance

Robin Mitchell rdmitchell at lbl.gov
Mon Apr 9 15:11:30 PDT 2007


The glazing system gap data is in the EnergyPlus file that WINDOW 5.2
generates (it is a text file so you can look at it with a text editor), so
presumably the problem happens when this WINDOW 5.2 file is used in Equest.


Robin Mitchell
Windows & Daylighting Group
Lawrence Berkeley National Laboratory

 


-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Ery Djunaedy
Sent: Saturday, April 07, 2007 11:54 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] EQuest question: glass conductance

Vikram and Marlin: Thanks for your reply

All:

> We need to add an expression to the GLASS-CONDUCTANCE input (also the 
> VIS-TRANS and OUTSIDE-EMISS) that mark these as unused for glass types 
> fetched from the glass library.

Even better, you can block out these cells if the glass type refers to the
library. The reason for my question is because the Shading Coefficient cell
is blocked out if we select the library, while these other cells (including
the glass conductance) is not blocked. The logical conclusion is that EQuest
will look at the library if it needs SC, but still need the values of the
GLASS-CONDUCTANCE, VIS-TRANS and OUTSIDE-EMISS. I would suggest to block
these cells if the library is selected.

On importing from Windows5:

The reason I ask this question is when I imported glass properties from
Windows5, I found that the windows conduction jumps compared to my baseline
scenario.

The glass conductance value was the immediate suspect, but it turned out
that this is not the problem.

The problem for my case was that every time I imported the window, the gap
between the panes was set to zero. The import filter can pick up the gas
fill between the pane, but it failed to import the gap distance. No warning
was issued so I initially accepted that the import is fine. Only after
digging into the imported properties one by one, then I found that the gaps
are set to zero.

Solution/Work around: Save the EQuest file after import. close EQuest and
open the input file (.inp) in the text editor. Find the imported glazing in
the glass section, type in 12mm (or whatever the gap is), and that's it.

The next time you import from Window5, and wonder why the window conduction
jump, check the gap between the panes.

I suspect this is a bug in the EQuest filter from Window5. I have only
tested it with a few different windows configuration, and the behaviour
seems consistent.

Regards,

Ery




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