[Equest-users] URGENT: Window U-values: Total window assemblyv/s Glass only
Omar Katanani
omar at ecoconsulting.net
Wed Aug 3 08:22:51 PDT 2011
Indeed there are many ways to model windows! I am kind of lost on how to
proceed.
I think I'm going to directly response to the Review comment by arguing
that eQUEST captures frame effects.
"It is It is unclear whether the window U-value of 0.26 and SHGC of 0.28
used for the Proposed case accounts for the impact of the window frames
on the whole assembly as required by ASHRAE modeling protocol. Please
provide additional information to confirm that the framed assembly
U-value was used for the Proposed case windows (e.g. showing that the
whole window assembly has been tested by NFRC, or verifying that LBNL
Window5 calculations have been provided for the whole assembly, or
verifying that the frame effects are captured within the energy modeling
software), or revise the model referencing ASHRAE 90.1-2007 Table A8.2
if needed."
I mean, I got 1 or 2 responses in this thread arguing that eQUEST does
indeed capture frame effects. The issue is that no single manufacturer
has heard of NFRC in Lebanon (and there are no documented standards on
frames in Lebanon), and U-values of Table A8.2 are much, much higher
than what's proposed, so using these A8.2 values in my proposed case
will increase my energy consumption considerably!
Best regards,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
Nahas Building, 4th floor
4 St-Maron Street / Georges Haddad Avenue
Postal Code: 2028 5806 SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 266
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989
Fax: +44 (0) 207 939 0981
Website: www.ecoconsulting.net <http://www.ecoconsulting.net/>
________________________________
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Brad
Robinson
Sent: 02 August 2011 21:24
To: R B; eQUEST Users List
Subject: Re: [Equest-users] URGENT: Window U-values: Total window
assemblyv/s Glass only
There are, it seems, a multitude of ways people on this forum go about
modeling windows. It would be interesting to know, in terms of a LEED
review, what others have been required to provide in terms of modeling
the windows. Does anyone have experience on the Canadian side of the
border what is required? Thanks.
Brad Robinson
________________________________
From: R B <slv3sat at gmail.com>
To: eQUEST Users List <equest-users at lists.onebuilding.org>
Sent: Saturday, July 30, 2011 11:29:31 PM
Subject: Re: [Equest-users] URGENT: Window U-values: Total window
assembly v/s Glass only
Came across this in eQuest help - basically suggests to use zero frame
width.
-Rohini
Volume 2: Dictionary > Envelope Components > WINDOW > Window Frames and
Skylight Curbs
FRAME-WIDTH
Projected width of the frame in the plane of the glazing (Figure 27). We
recommend that frames be entered only if the frame area is more than 10
percent or so of the glazed area, which is generally only the case in
residential applications. The program assumes that the frame width is
the same on all sides of the window. If this is not the case, use the
average frame width.
On Fri, Jul 29, 2011 at 4:15 PM, Alex Krickx <akrickx at seriousenergy.com>
wrote:
Great thread-
To answer Vikram's question - When using WINDOW, you are slightly
limited in the output file (for example, if I create an NFRC-type model
to figure out U-value for a curtainwall system, I will need to simply
the window to export it into a DOE-2 report format). When you do import
a WINDOW Report for DOE-2 into eQUEST it does not load any frame
information with it - it presents the COG glass performance. My process
is to adjust the spacer type and frame width+conductance to make an
object that matches what WINDOW tells me my window performance is.
I don't model for LEED, so am less familiar with what is required for
that - since I work for a window manufacturer I usually have access to
all the data I need to determine frame-inclusive u-value and SHGCs, i.e.
no need to rely on 90.1 defaults.
Since the conversation was about using NFRC data - let me ask this
question: NFRC data for windows (curtainwall assemblies included) is for
a "default" size. I believe for curtainwall a mulled unit is modeled at
2m x 2m (or 78.54" x 78.54") - as shown below:
This is an example, but let's say that the NFRC value is U-0.34. If your
building has a smaller or larger window (which will change the
glass-to-frame ratio) the U-value will be different.
Is it still appropriate to use the NFRC value in that case, where it is
entered as a frame-inclusive U-factor and SHGC? I'm curious as to how
others approach this issue when dealing with models for compliance.
Kind regards,
Alex Krickx
Alex Krickx, LEED AP
Building Energy Specialist
Serious Energy, Inc.
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124
akrickx at seriousenergy.com
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From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Friday, July 29, 2011 1:39 PM
To: Robby Oylear; Bill Talbert; Carol Gardner
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] URGENT: Window U-values: Total window
assembly v/s Glass only
Firstly - congratulations to all contributors - I think this is probably
the first time (that I recall) that all of the posts on this list have
been on a single thread. I couldn't resist being a part of this so I'm
going to add my 2 cents:
90.1 baseline values & SHGC are assembly u-values so your frame needs to
be calculated into this. To get the derated value - you could either use
the handy little XL spreadsheet that comes with the install of eQUEST
(under the data\window folder) called eQUEST-DOE2 Glass Library.xls.
This gives you COG values AND glass+frame NFRC values. They have
separate table where it is sorted by U-value and SHGC - I use it all the
time (screenshot below).
So you can select your values in conjunction with the values below from
the DOE2 help file to get what you need.
Frame Type
FRAME-CONDUCT (excludes OA film)
U-valuea
Thermally unbroken aluminum
3.037 (17.24)
1.90 (10.79)
Thermally broken aluminum
1.245 (7.07)
1.00 (5.68)
External flush glazed aluminum
0.812 (4.61)
0.70 (3.97)
Wood with or without cladding
0.434 (2.46)
0.40 (2.27)
Vinyl
0.319 (1.81)
0.30 (1.70)
a U-value includes OA film at 15 mph [6.7 m/s] windspeed
FRAME-CONDUCT = [(U-value)-1 - 0.197]-1 Btu/ft2-F-h
FRAME-CONDUCT = [(U-value)-1 - 0.035]-1 W/m2-K
Alternately, you can select a COG value to match what you want, set your
frame to zero and your spacer to UE-EQ-UC (this will give you a uniform
COG conductance across the assembly).
I am curious about LBNL window imports. When you set up your assembly in
window - it includes frames, but you import it in as a glass type -
should you zero out the frame (as in the second case) if you import from
window?
Vikram Sami, LEED AP BD+C
Sustainable Design Analyst
1315 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462 f: 404.892.5823 e: vikram.sami at perkinswill.com
www.perkinswill.com <http://www.perkinswill.com/>
Perkins+Will. Ideas + buildings that honor the broader goals of society
From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby Oylear
Sent: Friday, July 29, 2011 4:18 PM
To: Bill Talbert; Carol Gardner
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] URGENT: Window U-values: Total window
assembly v/s Glass only
>From the 90.1 User's Manual pg 5-12:
"With Addendum 90.1ag (published
with Standard 90.1-2001) glazed wall
systems, including glass curtain walls used
on large buildings, storefront glazing
systems, and other similar products that
are assembled at the construction site, as
opposed to at the factory, must either be
rated using NFRC procedures or the
default U-factor, SHGC and VLT from
Table A8.2. Since the performance values
in Table A8.1A are based on uncoated
clear glass in poorly performing metal
frame, they do not offer any credit for
low-e coatings, thermal break frames or
any other advanced feature. In general,
values from Table A8.1A will not achieve
compliance with the fenestration
requirements.
The NFRC procedure for site-built
fenestration is described in NFRC 100.
The NFRC ratings are based on computer
simulations of various product options at
standard sizes. (For curtain walls, the
standard size specified is 2000 mm by
2000 mm, or approximately 79 in. by 79
in.) Multiple glass options can be included
in one simulation matrix. The entire
simulation matrix is then validated by a
single physical test at the standard size. If
the matrix for a product has previously
been validated, then a new glass option
can be added to the matrix by simulation
alone. Simulations and tests must be done
by an NFRC-accredited simulation and
test laboratories."
Also, the LEED Reference Guide for Green Building Design and
Construction, pg 275 specifically references Tables A8.1 and A8.2 or
requires that the products be certified and labeled in accordance with
NFRC.
Not seeing any statements that would allow the modeler to perform their
own fenestration assembly performance calculations.
-Robby
On Fri, Jul 29, 2011 at 12:02 PM, Bill Talbert <btalbert at aeieng.com>
wrote:
Regarding Omar's first question, I would also clarify that adding a
frame to the baseline is probably not the correct approach unless you
are adjusting the U-value to a center of glass value and accounting for
the frame and edge effects such that the total fenestration performance
is equal to the 90.1 prescribed value.
'They are silent about frames but I would use one, match the frame width
of your proposed window. Use an Aluminum frame with no thermal break.'
Baseline Table 5.5-1 through 5.5-8 specify 'fenestration assembly'
values which include the effect of the frames and edge of glass.
Modeling a frame in the Baseline will further degrade the overall
fenestration U-value (unless your frame outperforms the glazing) and
result in overestimating the savings relative to the fenestration
performance. If you use the Table values for your window performance,
frames shouldn't be included. If you include a frame, you should create
a 90.1 compliant product using WINDOW and use the appropriate frame and
glazing performance values as eQuest inputs such that your overall frame
and glazing performance matches the A90.1 Table value.
Regards,
Bill
Bill Talbert PE, LEED(r) AP
Sustainable
AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Boulevard | Madison, WI 53719
P: 608.441.6677 | C: 608.234.3803 | F: 608.238.2614
btalbert at aeieng.com <mailto:btalbert at aeieng.com> | www.aeieng.com
<http://www.aeieng.com/>
From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Carol Gardner
Sent: Friday, July 29, 2011 1:35 PM
To: Robby Oylear
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] URGENT: Window U-values: Total window
assembly v/s Glass only
This came off of the Window website:
WINDOW 6.3 is a publicly available computer program for calculating
total window thermal performance indices (i.e. U-values, solar heat gain
coefficients, shading coefficients, and visible transmittances). WINDOW
6.3 provides a versatile heat transfer analysis method consistent with
the updated rating procedure developed by the National Fenestration
Rating Council (NFRC) that is consistent with the ISO 15099 standard.
The program can be used to design and develop new products, to assist
educators in teaching heat transfer through windows, and to help public
officials in developing building energy codes.
On Fri, Jul 29, 2011 at 11:26 AM, Robby Oylear <robbyoylear at gmail.com>
wrote:
Carol,
I have to take exception to this:
"As far as NFRC, your Solarban glass data is NFRC rated which should be
good enough, I think. It's rare in commercial buildings to have a rating
for the entire window."
>From my first response:
In order to meet LEED EAp2 Minimum Energy Performance, the project must
comply with all mandatory provisions of ASHRAE 90.1-2007. Section 5.4.2
Fenestration and Doors requires that fenestration performance be
determined per section 5.8.2. Section 5.8.2.4 U-factor requires that
the U-factor for the overall fenestration area (including framing) be
determined in accordance with NFRC 100. If you do not have NFRC data
available, values from section A8.2 are the only acceptable alternative.
NFRC values for the glazing alone not "good enough". This is exactly
what the reviewer is trying to get at.
I'd hardly call NFRC certification rare. In the State of Washington
NFRC certification has been required for all glazing assemblies for over
10 years.
How do you justify certifying that your projects have met the mandatory
provisions of ASHRAE 90.1 without NFRC data?
Robby Oylear, LEED(r) AP BD+C
Mechanical Project Engineer
Energy Analyst
D 206-788-4571 | C 206-354-2721
www.rushingco.com <http://www.rushingco.com/>
On Fri, Jul 29, 2011 at 11:12 AM, Carol Gardner <cmg750 at gmail.com>
wrote:
On Thu, Jul 28, 2011 at 5:40 AM, Omar Katanani <omar at ecoconsulting.net>
wrote:
Dear all,
Thank you for your responses.
1. Are the NFRC testing and the values in table A8.2 used
for the Baseline, Proposed, or both scenarios?
For the baseline windows, Appendix G gives the following instructions:
Fenestration
U-factors shall match the appropriate requirements in Tables 5.5-1
through
5.5-8. Fenestration SHGC shall match the appropriate requirements in
Tables
5.5-1 through 5.5-8.
They are silent about frames but I would use one, match the frame width
of your proposed window. Use an Aluminum frame with no thermal break.
2. Let's say I do not have NFRC test results and decide to
use the values in table A8.2. For a clear double glazed and metal frame
type, I get an assembly U-factor of 5.1. How can I input this into
eQUEST? As far as I know, I can enter the glass properties and the frame
properties. Do I have to play with the glass properties and check the
LV-D report for the calculated Assembly u-value?
A U of 5.1 does not make sense. Are you sure this isn't R?
Similarly, for the baseline, Tables 5.5-1 to 5.5-8 of ASHRAE
90.1 provide the assembly u-values for vertical glazing. How can I enter
these values into eQUEST?
3. I am attaching the specs of the proposed glazing. These
numbers are for the glass only (note that the u-values reported are NFRC
ones). Additionally, I know that the frame will be aluminium. Do I still
need NFRC U-values for the whole assembly, or is the NFRC usually for
the glass only? If yes, how can I calculate the whole assembly U-value
(given that eQUEST doesn't have the ability to calculate this)
For your proposed building I highly recommend you use LBNL's Window
program. In it you can select your window type, e.g. casement, picture,
etc,, select your glass from their glass library, which is huge and
definitely includes Solarban, and then model your frame using whatever
information the architect gives you related to thermal breaks and
spacers. After you run your window in the program you can select to save
it to a DOE 2 report which will automatically go into your DOE 2 Window
folder. Then you just have to select it from the pull down menu.
Otherwise, input your glass values, as you are already, and input your
frame data, the same data you got from your architect, and model it that
way. When you look at your LV-D report you will likely see a variety of
U values. That's because they will vary based on window size.due to the
frame effect. You need to have a frame.
As far as NFRC, your Solarban glass data is NFRC rated which should be
good enough, I think. It's rare in commercial buildings to have a rating
for the entire window.
Carol
Thanks for clarifying this, as my project is outside the US and
we are not too familiar with standards such as NFRC.
Best regards,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
Nahas Building, 4th floor
4 St-Maron Street / Georges Haddad Avenue
Postal Code: 2028 5806 SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 266
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989
Fax: +44 (0) 207 939 0981
Website: www.ecoconsulting.net <http://www.ecoconsulting.net/>
________________________________
From: Robby Oylear [mailto:robbyoylear at gmail.com]
Sent: 28 July 2011 00:53
To: Omar Katanani
Cc: Brad Robinson; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] URGENT: Window U-values: Total
window assembly v/s Glass only
Omar,
To directly answer your question:
"I'm assuming that, given that I entered the u-values for the
glass only, and then I entered information about the frame, then I need
not worry about any conversions in U-values, since eQUEST has all the
necessary information to calculate the equivalent u-value of the whole
pane + frame assembly,right?"
No. Your method will result in an assembly U-value based on
your input glass conductance and whatever default frame properties that
the eQUEST wizard will use. I have never tried to let eQUEST determine
an assembly value, as NFRC values are required for LEED and code
compliance studies. I would not be surprised if the values eQUEST is
calculating (shown in LV-D and LV-E reports like previously mentioned)
are much different than what you'll actually see in the test results.
Again, NFRC values are a LEED requirement, so unless you're just
doing preliminary analysis for a client, you need to receive NFRC
simulation reports or certified product directory numbers in accordance
with NFRC 100.
Robby Oylear, LEED(r) AP BD+C
Mechanical Project Engineer
Energy Analyst
D 206-788-4571 | C 206-354-2721
www.rushingco.com <http://www.rushingco.com/>
On Wed, Jul 27, 2011 at 2:44 PM, <omar at ecoconsulting.net> wrote:
Dear Robby,
Yes, I am modeling for LEED purposes.
I'll look into A8.2. But at least, is my method correct for the
proposed scenario?
Brad: I think you need to enter the center of glass u-value in
the "Glass Type", and then enter the frame properties in the "Window"
properties...
Best,
Omar
Quoting Brad Robinson <brad.robinson at yahoo.com>:
Is the u-value listed for a manufacturer and specific
model on the NRCAN website centre of glass or overall assembly? Many
windows are custom made to suit so I am unclear if each individual
custom window would need to be tested.
In eQuest, when entering the window, if the u-value
represents the whole window, including frame, do you need to enter a
frame width, conductance etc as well under the Window Frame section
under Window Properties? Thanks.
Brad Robinson
________________________________
From: Robby Oylear <robbyoylear at gmail.com>
To: Omar Katanani <omar at ecoconsulting.net>
Cc: equest-users at lists.onebuilding.org
Sent: Wednesday, July 27, 2011 12:32:08 PM
Subject: Re: [Equest-users] URGENT: Window U-values:
Total window assembly v/s Glass only
Omar,
The answer depends on the purpose of your study. If
you're trying to get results for a client on the impact of the glazing
on their energy performance, this may be adequate. Make sure you've
entered in the framing information properly (metal vs. non-metal).
I'd recommend opening up your simulation output results
file (xxxx.SIM) and going to the either the last page of the LV-D report
or sort through your LV-E report to see what value eQUEST has
calculated. Compare these values to the ASHRAE Fundamentals results for
overall assembly values including frame to see how close you've come. I
would not blindly trust that eQUEST will give you an appropriate overall
assembly value based on entering only the center of glass number.
However, if this is for a LEED study, this is not
adequate. This an excerpt from an e-mail I sent out recently regarding
LEED and NFRC requirements.
In order to meet LEED EAp2 Minimum Energy Performance,
the project must comply with all mandatory provisions of ASHRAE
90.1-2007. Section 5.4.2 Fenestration and Doors requires that
fenestration performance be determined per section 5.8.2. Section
5.8.2.4 U-factor requires that the U-factor for the overall fenestration
area (including framing) be determined in accordance with NFRC 100. If
you do not have NFRC data available, values from section A8.2 are the
only acceptable alternative.
Robby Oylear, LEED(r)AP BD+C
Mechanical Project Engineer
Energy Analyst
D206-788-4571 |C206-354-2721
www.rushingco.com
On Wed, Jul 27, 2011 at 8:14 AM, Omar Katanani <
omar at ecoconsulting.net> wrote:
Dear all,
I have a small question regarding entering
window properties to eQUEST:
I have read a lot of emails in the forum
discussing NFRC testing, LBNL Window 5 import, and other
topics that I haven?t
paid attention to before.
The way I modelled my windows is the
following:
1. I have manufacturer?s specifications
listing the glass U-values, not the total assembly.
2. In the ?Glass Types? (eQUEST Detailed
Mode), I created glass types, and entered the glass conductance, visible
transmittance, SC, and emissivity from the manufacturer?s details I
have.
3. When creating windows, I specify which
glass type (from the ones I created in step 2), in addition to the frame
width and conductance.
I?m assuming that, given that I
entered the u-values for the glass only, and then I
entered information about
the frame, then I need not worry about any conversions
in U-values, since
eQUEST has all the necessary information to calculate
the equivalent u-value of
the whole pane + frame assembly, right?
I appreciate your feedback / comments
today if possible, as this has become really urgent!
Many thanks,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
NahasBuilding, 4th floor
4 St-Maron Street/ Georges Haddad Avenue
Postal Code: 2028 5806
SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 266
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989
Fax: +44 (0) 207 939 0981
Website: www.ecoconsulting.net
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