[Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only
Sami, Vikram
Vikram.Sami at perkinswill.com
Fri Jul 29 13:39:07 PDT 2011
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).
[cid:image004.png at 01CC4E0E.0897B350]
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<mailto: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<tel:608.441.6677> | C: 608.234.3803<tel:608.234.3803> | F: 608.238.2614<tel: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> [mailto: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<mailto: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<mailto: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<tel:206-788-4571> | C 206-354-2721<tel: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<mailto:cmg750 at gmail.com>> wrote:
On Thu, Jul 28, 2011 at 5:40 AM, Omar Katanani <omar at ecoconsulting.net<mailto: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.
1. 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?
1. 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<mailto: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<tel:%2B961%20%280%29%201%20971%20266>
Mobile: +961 (0) 3 045 045<tel:%2B961%20%280%29%203%20045%20045>
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989<tel:%2B44%20%280%29%20207%20939%200989>
Fax: +44 (0) 207 939 0981<tel:%2B44%20%280%29%20207%20939%200981>
Website: www.ecoconsulting.net<http://www.ecoconsulting.net/>
[cid:image001.jpg at 01CC4E0C.D12049B0]
________________________________
From: Robby Oylear [mailto:robbyoylear at gmail.com<mailto:robbyoylear at gmail.com>]
Sent: 28 July 2011 00:53
To: Omar Katanani
Cc: Brad Robinson; equest-users at lists.onebuilding.org<mailto: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<tel:206-788-4571> | C 206-354-2721<tel:206-354-2721>
www.rushingco.com<http://www.rushingco.com/>
On Wed, Jul 27, 2011 at 2:44 PM, <omar at ecoconsulting.net<mailto: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<mailto: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<mailto:robbyoylear at gmail.com>>
To: Omar Katanani <omar at ecoconsulting.net<mailto:omar at ecoconsulting.net>>
Cc: equest-users at lists.onebuilding.org<mailto: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<http://www.rushingco.com>
On Wed, Jul 27, 2011 at 8:14 AM, Omar Katanani <omar at ecoconsulting.net<mailto: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<mailto: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<tel:%2B961%20%280%29%201%20971%20266>
Mobile: +961 (0) 3 045 045<tel:%2B961%20%280%29%203%20045%20045>
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989<tel:%2B44%20%280%29%20207%20939%200989>
Fax: +44 (0) 207 939 0981<tel:%2B44%20%280%29%20207%20939%200981>
Website: www.ecoconsulting.net<http://www.ecoconsulting.net>
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