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

Brad Robinson brad.robinson at yahoo.com
Fri Jul 29 08:46:52 PDT 2011
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The values listed in Appendix A8.2 are for the fenestration opening.  Looking at the definition of fenestration it says "all areas (including the frames) in the buildingenvelope that let in light, including windows"
If the u-values listed includes the frame and I am assuming edge of glass effects,  it seems to me that the frame width in eQuest should be zero, or you would be including the frame twice.

Am I not understanding this correctly?  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: Friday, July 29, 2011 11:16:36 AM
Subject: Re: [Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only


Omar,

If I was the reviewer in this case I'd have trouble understanding how eQUEST is accounting for frame effects when you've set the frame width to zero.  Honestly, I think the only acceptable values you should be using are from the table in Appendix A if you don't have an equivalent nationally recognized certification program.  

Also, your SHGC looks really low compared to your visible transmittance.  Unless you're using some pretty impressive glazing or low-e coatings I'd expect the VT to be around 0.5-ish for a glazing assembly with an SHGC of 0.29.

Robby Oylear, LEED®AP BD+C
Mechanical Project Engineer
Energy Analyst
 
D206-788-4571 |C206-354-2721
www.rushingco.com

On Fri, Jul 29, 2011 at 6:55 AM, Omar Katanani <omar at ecoconsulting.net> wrote:

Thanks Bruce,
> 
>I have an additional question:
> 
>Ø       In the “Glass
prop.jpg” file attached, I entered the glass conductance as 0.6 Btu/h-ft2-F
>Ø       In the “Window
specs.jpg” file, I entered the frame width as zero.
>Ø       However, when I look at
my LV-D report, I notice that the Average U-value for the windows is 0.509 Btu/h-ft2-F
> 
>Why is this number different from the
glass conductance, given that I am assuming the frame width zero (i.e, the window
is only composed of glass)?
> 
>I need to figure this out in order to
argue with the LEED Reviewer that eQUEST has the ability to capture frame effects.
> 
>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
> 
> 
>
>________________________________
> 
>From:Bruce Easterbrook [mailto:bruce5 at bellnet.ca] 
>Sent: 28 July 2011 19:36
>To: Omar Katanani
>
>Subject: Re: [Equest-users]
URGENT: Window U-values: Total window assembly v/s Glass only
> 
>I would try showing the frame effects are accounted
for.  I checked my ASHRAE Fundamentals text and the SHGC numbers seem
close for 6mm glass double glazed with an aluminum frame in Table A8.2. 
This is a complicated area and I don't get this deep into it.  This also
seems to be a LEED US wrinkle from the question.  The reference to
referencing A8.2 would only apply to the base case anyway not to your proposed
glass.  So it would seem to me you show eQuest does account for the
frames, which it does and that your proposed glass values are reasonable or you
look at NFRC and pick a manufacturer making a window close to what you are
proposing.  I think the biggest problem is the reviewer is not very
experienced and is just giving you a stock reply.
>Bruce
>
>
>On 28/07/2011 11:01 AM, Omar Katanani wrote: 
>Hi Bruce,
> 
>The project is in Lebanon, and there are pretty much no standards relating to energy whatsoever!
> 
>The LEED Review I got is the following:
> 
>“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.”
> 
>Can we argue that the frame effects are
captured within eQUEST, as per the underlined phrase?
> 
>Do you recommend using table A8.2, or are
its U-values too high?
> 
>Best regards,
>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
> 
> 
>
>________________________________
> 
>From:Bruce Easterbrook [mailto:bruce5 at bellnet.ca] 
>Sent: 28 July 2011 17:36
>To: Omar Katanani
>Cc: Robby Oylear; Brad Robinson; equest-users at lists.onebuilding.org
>Subject: Re: [Equest-users]
URGENT: Window U-values: Total window assembly v/s Glass only
> 
>Hi Omar,
>    This is where LEED and eQuest can get complicated.  As
you are outside the US the NFRC test results won't apply to you.  This is
a US window test standard.  Being from Canada we have CSA test
requirements for windows, we don't use NFRC.  Basically you need to use
the base standard for your country for your baseline.  LEED Canada has
adjusted the LEED documents in this area to reflect our testing agency and what
we consider a base window.  Has the country you are building in done the
same?
>    So to get you going I would assume a base window in eQuest
for the baseline.  Use 6mm clear glass, 1/2" air space, 6mm glass,
metal spacer.  Also pick a base frame as well, this would depend on the
type of building you are doing, so select a plain frame in common use, if metal
choose a frame without a thermal break.  This should be easy to defend on
a LEED review.  If there is a specific country version of LEED for your
location then you could adjust for this later once you get the required
information.  For your proposed you would build the window you are
considering using the window manufacturers specs.  All manufacturers will
not offer all glass types.  In the window industry there are the glass
manufacturers, they make the glass.  Window manufacturers buy the glass
and make the frames.  Now you can see the reasoning behind the NFRC
testing and testing the total window, glass and frame, it is window
manufacturer specific.  But it does make a conflict with eQuest and the
way it was programmed and the way windows are input.  Realistically the
frame it not going to make much difference except if it is metal and there is a
thermal break.  The glass being the overwhelming area of the window is
going to have the largest impact.  This is what you want to be playing
with in eQuest, determining the cost effectiveness of different types of glass
and the payouts.  As long as you operate from a realistic baseline which
is the current standard construction used in the country of the build then you
can evaluate your proposed glass because you are looking at differential costs
and savings.  If your baseline changes it won't make very much difference,
you have already been able to select your window, it will just effect the
payback period and it will be a minor difference.  This does let you get
98% of the window work done.
>Bruce Easterbrook P.Eng.
>Abode Engineering
>
>On 28/07/2011 08:40 AM, Omar Katanani 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?
> 
>	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?
>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)
> 
>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)
>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
> 
> 
>
>________________________________
> 
>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
> 
>D206-788-4571 |C206-354-2721
>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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>>Equest-users mailing list
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