[Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only
Robby Oylear
robbyoylear at gmail.com
Fri Jul 29 10:55:57 PDT 2011
Omar,
Table A8.2 is for the proposed case, when you do not have certified values
for the overall assembly. They are intended to be worse than the baseline
to encourage projects to follow the code guidelines for certified testing.
Baseline values shall be determined in accordance with the tables in Section
5, which you've likely already done.
I agree that you should enter the frame as zero width if you are entering
the simplified values in as assembly values under the glass parameters.
Though Solarban is a great product as far as glass is concerned, if the
product uses a poorly insulated aluminum frame, the value could be much
worse than the baseline.
My big concern here would be that you don't know what the performance of
your glazing assembly is. If you can show project specifications that
clearly describe the type of thermally broken frame that will be provided,
you could argue that the values in ASHRAE Fundamentals could be used instead
of ASHRAE Table A8.2.
You need to provide some justification for whatever assembly U-factor, SHGC,
and VT you end up using in your proposed case. Be that NFRC testing, ASHRAE
Table A8.2, or ASHRAE Fundamentals values.
*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 8:47 AM, Omar Katanani <omar at ecoconsulting.net>wrote:
> Robby,
>
>
>
> I was just doing some sensitivity analysis for my own sake when I put the
> frame width into zero.
>
> Should the values in table A8.2 be used for the Baseline? If that is the
> case, then I should use 5.1W/m2-C (0.9 Btu/h-ft2-F) for my case, which is
> much less stringent than the 3.41W/m2-C (0.6 Btu/h-ft2-F) and this would
> be to my advantage J
>
>
>
> However, if I am required to use A8.2 for the proposed, then I should the
> figure of 0.9 Btu/h-ft2-F with the baseline u-value being 0.6Btu/h-ft2-F.
> This would definitely worsen my thermal model results for LEED and very
> probably risk my 10% prerequisite of improvement over the baseline!
>
>
>
> The glazing is pretty impressive. I’m attaching the specs, highlighted in
> yellow. The Glass U-value if 0.26 Btu/h-ft2-F.
>
>
>
> Additionally, if I am to use the assembly U-value of 0.9 Btu/h-ft2-F for
> my baseline, what is the best way to enter it to eQUEST? Shall I enter the
> glass properties to 0.9 and zero out the frame width?
>
>
>
> Many thanks,
>
>
>
> 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:* 29 July 2011 18:17
> *To:* Omar Katanani
> *Cc:* Bruce Easterbrook; equest-users at lists.onebuilding.org
>
> *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*
>
> * *
>
> *D* 206-788-4571 | *C* 206-354-2721
>
> *www.rushingco.com* <http://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)
>
> 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:* 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)
>
> 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:* Bruce Easterbrook [mailto:bruce5 at bellnet.ca <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)
>
> 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 <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 <%2B961%20%280%29%201%20971%20266>
> 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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