[Bldg-sim] eQuest 90.1 Window U Values

Julia Beabout juliabeabout at yahoo.com
Fri May 23 11:35:48 PDT 2008

(I'm not an Equest user, so, my question is strictly coming from a glazing and window assembly composite U-value standpoint).  
I don't see how there can be a single formula to characterize the frame conductance.  Wouldn't the conductance of the frame be a function of the frame materials and construction....i.e. if it is insulated, thermally broken, wood, metal, pvc.....etc?

----- Original Message ----
From: Amanda Bogner <amanda at bvm-engineering.com>
To: "Bishop, Bill" <bbishop at PathfinderEngineers.com>; "Aulbach, John" <jaulbach at nexant.com>; Josh Greenfield <JGreenfield at primerachicago.com>; bldg-sim at lists.onebuilding.org
Sent: Friday, May 23, 2008 11:16:22 AM
Subject: Re: [Bldg-sim] eQuest 90.1 Window U Values

Since the glazingneeds to be modeled as an assembly, you also have to verify the correct frame conductance is being used.  This value is found in the detailed edits under the window details.   
Frame Conductance= 1 / [(1/u-value) - 0.197] 
So, by example, if the ASHRAE 90.1 fenestration assembly u-value = 0.57, the frame conductance should = 1/ [(1/0.57) - 0.197] = 0.642 
When this is used in conjunction with the correct glass conductance (as previously described), the output file will give the proper u-value averages on the LV-D report. 
Amanda Bogner, PE LEED AP
404.806.2018 EXT 103
404.806.2019 FAX

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Friday, May 23, 2008 9:11 AM
To: Aulbach, John; Josh Greenfield; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] eQuest 90.1 Window U Values

Will the glass-conductance conversion method give the “assembly” U-value?  I thought assembly U-value included the frame.  Also, what would you do to get the assembly SHGC?
Why not just pick an existing glass type code after finding one that most closely matches the desired assembly U-value and assembly SHGC?  I can usually find one that is close to, if not exactly the same as, the required values.  The best match I see from the DOE glass library for U=0.57 and SHGC=0.39 is GTC 6840 – Double Pilkington Arctic Blu/Air1/Clr6.
Select “Create another Glass Type Code” by right clicking on an existing code in your component tree.  Then “Load Component from Library” and pick 6840.  Then change the properties of the affected glass types to reflect the change in glass type code (above the glass type codes as listed in the component tree).
William Bishop, EIT, LEED® AP|Pathfinder Engineers LLP
Mechanical Engineer

3300 Monroe Ave., Suite 306
Rochester , NY   14618
TEL (585) 218-0730 Ext. 114
FAX (585) 218-0737 
bbishop at pathfinderengineers.com
PPlease consider the environment before printing this email


From:bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Aulbach, John
Sent: Thursday, May 22, 2008 7:34 PM
To: Josh Greenfield; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] eQuest 90.1 Window U Values
Under DOE2 Help, Dictionary/Glass-Type..
The conductance of the glazing, excluding the outside air film coefficient. The conductance given in glass manufacturers' data sheets usually includes the outside air film resistance for a wind speed of 7.5 mph (summer) or 15 mph (winter). Table 10 can be used to obtain the corresponding value of GLASS-CONDUCTANCE. For example, if U(7.5 mph) = 0.64 Btu/ft2-hr-F, then GLASS-CONDUCTANCE = 0.79 (by interpolation). For U-values of different glazing types, see manufacturers' data sheets or the ASHRAE 1989 Handbook of Fundamentals, p. 27.16-17.
Table 10  
Correspondence between Glass manufacturers U-value and GLASS-CONDUCTANCE
(excluding outside air film) [all values are in Btu/ft2-hr-F (W/m2-K)]
(including outside air film) GLASS CONDUCTANCE 
(7.5 mph wind speed) (15 mph wind speed) 
0.1 (0.57) 0.10 (0.57) 0.10 (0.57) 
0.2 (1.14) 0.21 (1.19) 0.21 (1.19) 
0.3 (1.70) 0.33 (1.87) 0.32 (1.82) 
0.4 (2.27) 0.45 (2.56) 0.43 (2.44) 
0.5 (2.84) 0.59 (3.35) 0.55 (3.12) 
0.6 (3.41) 0.73 (4.14) 0.68 (3.86) 
0.7 (3.97) 0.89 (5.05) 0.81 (4.60) 
0.8 (4.54) 1.05 (5.96) 0.95 (5.39) 
0.9 (5.11) 1.23 (6.98) 1.09 (6.19) 
1.0 (5.68) 1.43(8.12) 1.24 (7.04) 
1.1 (6.25) 1.64 (9.31) 1.40 (7.95) 
1.2 (6.81) 1.87 (10.62) 1.57 (8.91) 
1.3 (7.38) 2.13 (12.09) 1.74 (9.88) 
Convert your GLASS-CONDUCTANCE to come up with the appropriate U-Value.
See the attached for an ASHRAE window I did.
Why didn't you start with the ASHRAE run as Base, rather than the Proposed model first?
John R. Aulbach, PE, CEM
Project Manager
Nexant, Inc.
701 West Kimberly Ave., Suite 245
Placentia, CA 92870-6342 USA
Phone: 714-524-4402
Fax: 714-524-4407
email: jaulbach at nexant.com


From:bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Josh Greenfield
Sent: Thursday, May 22, 2008 3:42 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] eQuest 90.1 Window U Values
I’m to the point in an Energy Model where I’m changing my ‘Proposed Model’ to my ‘Baseline Model’ and I’m having issues changing the window data.  For the ASHRAE 90.1 region, the Assembly U value needs to be set to 0.57 and the Assembly SHGC needs to be set to 0.39…where do I input these numbers??  The only window data values eQuest is letting me change is Glass Conductance, VLT and Emissivity…
Josh Greenfield , PE, LEED AP
Senior Associate
Primera Engineers, Ltd.
100 S. Wacker Drive, Suite 700
Chicago , IL 60606
312.606.0910 Main
312.242.6392 Direct
312.606.0415 Fax
jgreenfield at primerachicago.com
Be Green...please consider the environment before printing this email.
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