[Bldg-sim] eQuest 90.1 Window U Values

[Amanda Bogner]

When the assembly u-value of the glazing system (window + frame) is
determined, the frame properties you described are taken into account.  The
equation below is just to convert all of this to something that eQuest will
use...
 
In the baseline case, ASHRAE 90.1 stipulates what the assembly value needs
to be.  For the actual design, an assembly value will need to be determined
using real frame data and center of glass u-values.  Check out LBNL's Window
5 software for more info.
 
Amanda
BVM Engineering, Inc.
404.806.2018 x103
 

  _____  

From: Julia Beabout [mailto:juliabeabout at yahoo.com] 
Sent: Friday, May 23, 2008 1:36 PM
To: Amanda Bogner; Bishop, Bill; Aulbach, John; Josh Greenfield;
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] eQuest 90.1 Window U Values


(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 glazing needs 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, LEEDR 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

 

www.pathfinderengineers.com

P Please 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..


 


GLASS-CONDUCTANCE


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)]


U-Value
(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)

 

Josh:

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
 <http://www.primerachicago.com/> http://www.primerachicago.com

Be Green...please consider the environment before printing this email.

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20080523/629e9ca6/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/bmp
Size: 24894 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20080523/629e9ca6/attachment-0002.bin>