[Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only

[Robby Oylear]

>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® 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  |  *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**®** 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.****
>
>  ****
>
>    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****
>
>  ****
>
> 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****
>
>  ****
>
>  ****
> ------------------------------
>
> *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® 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®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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>
>
> --
> Carol Gardner PE****
>
> ** **
>
>
>
>
> --
> Carol Gardner PE****
>
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