[Equest-users] Window "Curb"

[Alex Krickx]

Thanks Bruce and Jeremy,

Well, you've answered my question but I still have the same problem: how to account for edge-of-glass effects in eQUEST (the edge of glass U-value will be between the frame and COG values). Back to the drawing board I guess. Thanks for the responses.

Kind regards,
Alex Krickx

From: Jeremy Goth [mailto:jngoth at hotmail.com]
Sent: Wednesday, January 05, 2011 8:26 AM
To: Alex Krickx
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Window "Curb"

Go to your building shell and navigate to the space/roof/skylight in the component tree.  Select the skylight then go to the spreadsheet tab on the right and find 'Skylight Surface - Curb - Performance'.

Jeremy

________________________________
Date: Tue, 4 Jan 2011 20:00:19 -0500
From: bruce5 at bellnet.ca
To: akrickx at seriousmaterials.com
CC: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window "Curb"

    A curb is used to lift the window up off the roof and allow the window to be flashed and made water tight.  It can be as simple as a 2x6 or 2x8 wood box.  A complicated one would be a fully insulated wall tunnel through a roof truss system.  It should be modelled as an exterior wall.  There should be no edge of glass effect as all the glass should be inside the opening.  There will be an edge/corner effect where the window frame sits on the curb.
Bruce Easterbrook P.Eng.
Abode Engineering


On 04/01/2011 04:12 PM, Alex Krickx wrote:
Hi everyone,

Happy New Year! Well, to start off the new year, I have a question on what the "curb" is in the LV-H report. The placement of the information, and the fact that it has an area and U-value (much the way the window frame does) leads me to believe it may be to account for Edge-of-Glass effects (if you look at Window5 outputs it has COG U-values, frame U-values and edge-of-glass U-values).

I can't see anywhere in the detailed edit mode to input curb information - I looked in both the "Glass Type Properties" and "Window Properties" Screens.

I found the following info in the DOE2 help file, but it looks like it only applies to skylights? It also wasn't clear if it was in fact for edge of glass, and how to add this information (I'm guessing in the INP file?). Thanks for any help.

CURB -CONDUCT
Conductance of the skylight curb, excluding the outside air film but including the inside air film.
Notes:
1.     You can define curbs only for exterior windows and skylights, not for interior windows.
2.     If the CURB-HEIGHT is zero no curb calculations will be performed.
3.     The curb area is not subtracted from the associated exterior wall area.
4.     Each hour, the program adds the effect of a wind speed-dependent outside air film to the user specified CURB-CONDUCT.
5.     The various elements of a curb (top, bottom, side, dividers, etc.) may have different conductances. In this case, CURB-CONDUCT should be an area-weighted average of the different elements.
6.     The program finds the overall window conduction by adding curb, frame, edge-of-glass, and center-of-glass contributions. Thus, all three of these contributions are included in each of the following report quantities:
          "Window Conduction" in summary reports LS-B, LS-C, LS-E, and LS-F;
          "Window U-Value" and "Window Area" in verification report LV-D and LV-H;
          WINDOW hourly report variable #1, "Window U-Value".
7.     A WINDOW multiplier also multiplies the curb area.
8.     Window fins and overhangs shade the curb as well as the glazing.
9.     Shading devices, like blinds and drapes, that you specify using the WINDOW keywords SHADING-SCHEDULE and CONDUCT-SCHEDULE, affect only the glazed part of the window. They do not affect the heat conduction through the curb.
10.   If the window has a setback, the curb is also set back by the same amount.

Kind regards,
Alex Krickx

Alex Krickx, LEED AP
Building Energy Specialist
Error! Filename not specified.
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

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